Takeshi Matsuda, Tatsuhiro Hisatsune (Handling Associate Editor: Shun Shimohama)
Cholinergic Modification of Neurogenesis and Gliosis Improves the Memory of AβPPswe/PSEN1dE9 Alzheimer’s Disease Model Mice Fed a High-Fat Diet
Abstract: We previously reported that neuroinflammation contributes to the amnesia of AβPPswe/PSEN1dE9 Alzheimer’s disease model mice fed a high-fat diet to induce type-2 diabetes (T2DM-AD mice), but the underlying mechanism for the memory decline remained unclear. Recent studies have suggested that cholinergic modulation is involved in neuroinflammatory cellular reactions including neurogenesis and gliosis, and in memory improvement. In this study, we administered a broad-spectrum cholinesterase inhibitor, rivastigmine (2 mg/kg/day, s.c.), into T2DM-AD mice for 6 weeks, and evaluated their memory performance, neurogenesis, and neuroinflammatory reactions. By two hippocampal-dependent memory tests, the Morris water maze and contextual fear conditioning, rivastigmine improved the memory deterioration of the T2DM-AD mice (n = 8, p < 0.01). The number of newborn neurons in the hippocampal dentate gyrus was 1138 ± 324 (Ave ± SEM) in wild-type littermates, 2573 ± 442 in T2DM-AD-Vehicle, and 2165 ± 300 in T2DM-AD-Rivastigmine mice, indicating that neurogenesis was accelerated in the two T2DM-AD groups (n = 5, p < 0.05). The dendritic maturation of new neurons in T2DM-AD-Vehicle mice was severely abrogated, and rivastigmine treatment reversed this retarded maturation. In addition, the hippocampus of T2DM-AD-Vehicle mice showed increased proinflammatory cytokines IL-1β and TNF-α and gliosis, and rivastigmine treatment blocked these inflammatory reactions. Rivastigmine did not change the insulin abnormality or amyloid pathology in these mice. Thus, cholinergic modulation by rivastigmine treatment led to enhanced neurogenesis and the suppression of gliosis, which together ameliorated the memory decline in T2DM-AD model mice.
Angharad R. Morgan, Samuel Touchard, Caroline O’Hagan, Rebecca Sims, Elisa Majounie, Valentina Escott-Price, Lesley Jones, Julie Williams, B. Paul Morgan
The Correlation between Inflammatory Biomarkers and Polygenic Risk Score in Alzheimer’s Disease
Abstract: Plasma biomarkers to aid the early diagnosis of Alzheimer’s disease (AD) or to monitor disease progression have long been sought and continue to be widely studied. Biomarkers that correlate with AD polygenic risk score, a measure of the polygenic architecture of the disease and highly predictive of AD status, would be excellent candidates. Therefore, we undertook a preliminary study to assess the association of plasma inflammatory biomarkers with an overall AD polygenic risk score as well as with an inflammation-specific AD polygenic risk score in a sample set of 93 AD cases. We measured five complement biomarkers [complement receptor 1 (CR1), clusterin, complement component 9 (C9), C1 inhibitor (C1inh), terminal complement complex (TCC)] and the benchmark inflammatory marker C-reactive protein (CRP). Plasma clusterin level showed an association with overall AD polygenic risk score, while clusterin, C1inh, and CRP levels each displayed some association with the inflammatory-specific AD polygenic risk score. The results suggest that elevated plasma levels of inflammatory biomarkers, including complement proteins, associate with polygenic risk scores in AD, further strengthening the link between genetic and biomarker disease predictors and indicating a potential role for these markers in disease prediction and patient stratification in AD.
François Sellal, David Wallon, Laurent Martinez-Almoyna, Cecilia Marelli, Abhinav Dhar, Hélène Oesterlé, Anne Rovelet-Lecrux, Stéphane Rousseau, Christina E. Kourkoulis, Jon Rosand, Zora Y. DiPucchio, Matthew Frosch, Claudine Gombert, Bertrand Audoin, Manuèle Mine, Florence Riant, Thierry Frebourg, Didier Hannequin, Dominique Campion, Steven M. Greenberg, Elisabeth Tournier-Lasserve, Gaël Nicolas (Handling Associate Editor: Jérémie Pariente)
APP Mutations in Cerebral Amyloid Angiopathy with or without Cortical Calcifications: Report of Three Families and a Literature Review
Abstract: Background. Specific APP mutations cause cerebral amyloid angiopathy (CAA) with or without Alzheimer’s disease (AD). Objective. We aimed at reporting APP mutations associated with CAA, describe the clinical, cerebrospinal fluid AD biomarkers, and neuroimaging features, and compare them with the data from the literature. Methods. We performed a retrospective study in two French genetics laboratories by gathering all clinical and neuroimaging data from patients referred for a genetic diagnosis of CAA with an age of onset before 66 years and fulfilling the other Boston revised criteria. We studied the segregation of mutations in families and performed a comprehensive literature review of all cases reported with the same APP mutation. Results. We screened APP in 61 unrelated French patients. Three mutations, located in the Aβ coding region, were detected in five patients from three families: p.Ala692Gly (Flemish), p.Glu693Lys (Italian), and p.Asp694Asn (Iowa). Patients exhibited CAA and progressive cognitive impairment associated with cortical calcifications in the Iowa and Italian mutation carriers, but not the patient carrying the Flemish mutation. Conclusions. This is the first evidence of cortical calcification in patients with an APP mutation other than the Iowa mutation. We discuss the radiological, cerebrospinal fluid, and clinical phenotype of patients carrying these mutations in the literature.
Erming Wang, Haihao Zhu, Xiaofan Wang, Adam Gower, Max Wallack, Jan Krzysztof Blusztajn, Neil Kowall, Wei Qiao Qiu (Handling Associate Editor: Weiming Xia)
Amylin Treatment Reduces Neuroinflammation and Ameliorates Abnormal Patterns of Gene Expression in the Cerebral Cortex of an Alzheimer’s Disease Mouse Model
Abstract: Our recent study has demonstrated that peripheral amylin treatment reduces the amyloid pathology in the brain of Alzheimer’s disease (AD) mouse models, and improves their learning and memory. We hypothesized that the beneficial effects of amylin for AD was beyond reducing the amyloids in the brain, and have now directly tested the actions of amylin on other aspects of AD pathogenesis, especially neuroinflammation. A 10-week course of peripheral amylin treatment significantly reduced levels of cerebral inflammation markers, Cd68 and Iba1, in amyloid precursor protein (APP) transgenic mice. Mechanistic studies indicated the protective effect of amylin required interaction with its cognate receptor because silencing the amylin receptor expression blocked the amylin effect on Cd68 in microglia. Using weighted gene co-expression network analysis, we discovered that amylin treatment influenced two gene modules linked with amyloid pathology: 1) a module related to proinflammation and transport/vesicle process that included a hub gene of Cd68, and 2) a module related to mitochondria function that included a hub gene of Atp5b. Amylin treatment restored the expression of most genes in the APP cortex toward levels observed in the wild-type (WT) cortex in these two modules including Cd68 and Atp5b. Using a human dataset, we found that the expression levels of Cd68 and Atp5b were significantly correlated with the neurofibrillary tangle burden in the AD brain and with their cognition. These data suggest that amylin acts on the pathological cascade in animal models of AD, and further supports the therapeutic potential of amylin-type peptides for AD.
Eva Louwersheimer*, Petra E. Cohn-Hokke*, Yolande A.L. Pijnenburg, Marjan M. Weiss, Erik A. Sistermans, Annemieke J. Rozemuller, Marc Hulsman, John C. van Swieten, Cock M. van Duijn, Frederik Barkhof, Teddy Koene, Philip Scheltens, Wiesje M. Van der Flier, Henne Holstege *These authors contributed equally to this work.
Rare Genetic Variant in SORL1 May Increase Penetrance of Alzheimer’s Disease in a Family with Several Generations of APOE-ε4 Homozygosity
Abstract: Background: The major genetic risk factor for late onset Alzheimer’s disease (AD) is the APOE-ε4 allele. However, APOE-ε4 homozygosity is not fully penetrant, suggesting co-occurrence of additional genetic variants. Objective: To identify genetic factors that, next to APOE-ε4 homozygosity, contribute to the development of AD. Methods: We identified a family with nine AD patients spanning four generations, with an inheritance pattern suggestive of autosomal dominant AD, with no variants in PSEN1, PSEN2, or APP. We collected DNA from four affected and seven unaffected family members and performed exome sequencing on DNA from three affected and one unaffected family members. Results: All affected family members were homozygous for the APOE-ε4 allele. Statistical analysis revealed that AD onset in this family was significantly earlier than could be expected based on APOE genotype and gender. Next to APOE-ε4 homozygosity, we found that all four affected family members carried a rare variant in the VPS10 domain of the SORL1 gene, associated with AβPP processing and AD risk. Furthermore, three of four affected family members carried a rare variant in the TSHZ3 gene, also associated with AβPP processing. Affected family members presented between 61 and 74 years, with variable presence of microbleeds/cerebral amyloid angiopathy and electroencephalographic abnormalities. Conclusion: We hypothesize that next to APOE-ε4 homozygosity, impaired SORL1 protein function, and possibly impaired TSHZ3 function, further disturbed Aβ processing. The convergence of these genetic factors over several generations might clarify the increased AD penetrance and the autosomal dominant-like inheritance pattern of AD as observed in this family.
Motonobu Fujishima, Atsushi Kawaguchi, Norihide Maikusa, Ryozo Kuwano, Takeshi Iwatsubo, Hiroshi Matsuda, for the Alzheimer’s Disease Neuroimaging Initiative (ADNI) and the Japanese Alzheimer’s Disease Neuroimaging Initiative (J-ADNI) (Handling Associate Editor: Stefan Teipel)
Sample Size Estimation for Alzheimer’s Disease Trials from Japanese ADNI Serial Magnetic Resonance Imaging
Abstract: Background: Little is known about the sample sizes required for clinical trials of Alzheimer’s disease (AD)-modifying treatments using atrophy measures from serial brain magnetic resonance imaging (MRI) in the Japanese population. Objective: The primary objective of the present study was to estimate how large a sample size would be needed for future clinical trials for AD-modifying treatments in Japan using atrophy measures of the brain as a surrogate biomarker. Methods: Sample sizes were estimated from the rates of change of the whole brain and hippocampus by the k-means normalized boundary shift integral (KN-BSI) and cognitive measures using the data of 537 Japanese Alzheimer’s Neuroimaging Initiative (J-ADNI) participants with a linear mixed-effects model. We also examined the potential use of ApoE status as a trial enrichment strategy. Results: The hippocampal atrophy rate required smaller sample sizes than cognitive measures of AD and mild cognitive impairment (MCI). Inclusion of ApoE status reduced sample sizes for AD and MCI patients in the atrophy measures. Conclusion: These results show the potential use of longitudinal hippocampal atrophy measurement using automated image analysis as a progression biomarker and ApoE status as a trial enrichment strategy in a clinical trial of AD-modifying treatment in Japanese people.
Vasilis Z. Marmarelis, Dae C. Shin, Takashi Tarumi, Rong Zhang
Comparison of Model-Based Indices of Cerebral Autoregulation and Vasomotor Reactivity Using Transcranial Doppler versus Near-Infrared Spectroscopy in Patients with Amnestic Mild Cognitive Impairment
Abstract: We recently introduced model-based "physiomarkers" of dynamic cerebral autoregulation and CO2 vasomotor reactivity as an aid for diagnosis of early-stage Alzheimer’s disease (AD) , where significant impairment of dynamic vasomotor reactivity (DVR) was observed in early-stage AD patients relative to age-matched controls. Milder impairment of DVR was shown in patients with amnestic mild cognitive impairment (MCI) using the same approach in a subsequent study . The advocated approach utilizes subject-specific data-based models of cerebral hemodynamics to quantify the dynamic effects of resting-state changes in arterial blood pressure and end-tidal CO2 (the putative inputs) upon cerebral blood flow velocity (the putative output) measured at the middle cerebral artery via transcranial Doppler (TCD). The obtained input-output models are then used to compute model-based indices of DCA and DVR from model-predicted responses to an input pressure pulse or an input CO2 pulse, respectively. In this paper, we compare these model-based indices of DVR and DCA in 46 amnestic MCI patients, relative to 20 age-matched controls, using TCD measurements with their counterparts using Near-Infrared Spectroscopy (NIRS) measurements of blood oxygenation at the lateral prefrontal cortex in 43 patients and 22 age-matched controls. The goal of the study is to assess whether NIRS measurements can be used instead of TCD measurements to obtain model-based physiomarkers with comparable diagnostic utility. The results corroborate this view in terms of the ability of either output to yield model-based physiomarkers that can differentiate the group of aMCI patients from age-matched healthy controls.
Marjaana Koponen, Heidi Taipale, Piia Lavikainen, Antti Tanskanen, Jari Tiihonen, Anna-Maija Tolppanen, Riitta Ahonen, Sirpa Hartikainen (Handling Associate Editor: Ane Nørgaard Christensen)
Risk of Mortality associated with Antipsychotic Monotherapy and Polypharmacy among Community-Dwelling Persons with Alzheimer’s Disease
Abstract: We aimed to analyze the risk of non-cancer mortality according to duration of antipsychotic use and to compare the risk associated with polypharmacy and monotherapy among community-dwellers with Alzheimer’s disease (AD). The risk of mortality between most frequently used antipsychotic drugs was compared. Data from a nationwide register-based MEDALZ study that included all 70,718 community-dwellers newly diagnosed with AD during 2005-2011 in Finland was utilized. Death, excluding cancer as direct cause of death, was extracted from Causes of Death Register. Incident antipsychotic use was compared with time without antipsychotics with Cox proportional hazard models. Antipsychotic use was associated with an increased risk of mortality (adjusted hazard ratio [aHR] 1.61; 95% Confidence Interval [CI] 1.53-1.70). The absolute difference in mortality rate was 4.58 (95% CI 4.53-4.63) deaths per 100 person-years. The risk of mortality was increased from the first days of use and attenuated gradually but remained increased even after two years of use (aHR 1.30; 95% CI 1.16-1.46). Compared with nonuse, antipsychotic polypharmacy (aHR 2.88; 95% CI 2.38-3.49) was associated with an increased risk of mortality than monotherapy (aHR 1.57; 95% CI 1.49-1.66). Haloperidol was associated with higher risk of mortality (aHR 1.52; 95% CI 1.14-2.02) and quetiapine with lower risk (aHR 0.84; 95% CI 0.75-0.94) compared with risperidone. In conclusion, the findings support current treatment guidelines on having a high threshold for antipsychotic initiation among persons with AD. Antipsychotic polypharmacy and long-term use should be avoided and drug choice should be weighed against risk/benefit evidence.
Pasi Lampela, Anna-Maija Tolppanen, Antti Tanskanen, Jari Tiihonen, Sirpa Hartikainen, Heidi Taipale
Anticholinergic Exposure and Risk of Pneumonia in Persons with Alzheimer’s Disease: A Nested Case-Control Study
Abstract: Background: Risk of pneumonia is increased in persons with Alzheimer's disease (AD). In some studies, anticholinergic drugs (AC) have been associated with an increased pneumonia risk. Objective: We analyzed the risk of pneumonia associated with ACs in persons with AD. Methods: We performed a nested case-control study using register-based data from a Finnish nationwide MEDALZ cohort including all community-dwelling persons diagnosed with AD during 2005-2011. Cases were identified based on pneumonia diagnoses (n=12,442) from hospital discharge and causes of death registers. Up to two controls without pneumonia were matched based on time since AD diagnoses, age, and gender for each case; AC use was measured using Anticholinergic Drug Scale. Results: Use of AC was associated with an increased risk of pneumonia (adjusted odds ratio (OR) 1.36, 95% confidence interval (CI) 1.29-1.43). However, there was no increased pneumonia risk in persons using level 3 ACs. Incident use was associated with higher risk of pneumonia (OR 2.68, 95% CI 2.15-3.34) than prevalent use (OR 1.48, 95% CI 1.40-1.57). Among persons using cholinesterase inhibitors (AChEIs), risk of pneumonia was increased in persons using also ACs (OR 1.53, 95%CI 1.41-1.66). Conclusion: ACs were associated with an increased risk of pneumonia in persons with AD, especially at the time of initiation of these drugs. AC use was associated with increased pneumonia risk also in persons using AChEIs. This risk should be carefully considered when treating AD patients.
Mercè Boada, Fernando Anaya, Pilar Ortiz, Javier Olazarán, Joshua R. Shua-Haim, Thomas O. Obisesan, Isabel Hernández, Joan Muñoz, Mar Buendia, Montserrat Alegret, Asunción Lafuente, Lluís Tárraga, Laura Núñez, Mireia Torres, Joan Ramon Grifols, Isidre Ferrer, Oscar L. Lopez, Antonio Páez
Efficacy and Safety of Plasma Exchange with 5% Albumin to Modify Cerebrospinal Fluid and Plasma Amyloid-β Concentrations and Cognition Outcomes in Alzheimer’s Disease Patients: A Multicenter, Randomized, Controlled Clinical Trial
Abstract: Background: Studies conducted in animal models and humans suggest the presence of a dynamic equilibrium of amyloid-β (Aβ) peptide between cerebrospinal fluid (CSF) and plasma compartments. Objective: To determine whether plasma exchange (PE) with albumin replacement was able to modify Aβ concentrations in CSF and plasma as well as to improve cognition in patients with mild-moderate Alzheimer’s disease (AD). Methods: In a multicenter, randomized, patient- and rater-blind, controlled, parallel-group, phase II study, 42 AD patients were assigned (1:1) to PE treatment or control (sham) groups. Treated patients received a maximum of 18 PE with 5% albumin (Albutein®, Grifols) with three different schedules: two PE/weekly (three weeks), one PE/weekly (six weeks), and one PE/bi- weekly (12 weeks), plus a six-month follow-up period. Plasma and CSF Aβ1-40 and Aβ1-42 levels, as well as cognitive, functional, and behavioral measures were determined. Results: CSF Aβ1-42 levels after the last PE compared to baseline were marginally higher in PE-treated group versus controls (adjusted means of variation: 75.3 versus -45.5 pg/mL; 95% CI: -19.8, 170.5 versus 135.1, 44.2; p=0.072). Plasma Aβ1-42 levels were lower in the PE-treated group after each treatment period (p<0.05). Plasma Aβ1-40 levels showed a saw-tooth pattern variation associated with PE. PE-treated patients scored better in the Boston Naming Test and Semantic Verbal Fluency (p<0.05) throughout the study. Neuropsychiatric Inventory scores were higher in controls during the PE phase (p<0.05). Conclusion: PE with human albumin modified CSF and plasma Aβ1-42 levels. Patients treated with PE showed improvement in memory and language functions, which persisted after PE was discontinued.
Lorene Zerah, Judith Cohen-Bittan, Mathieu Raux, Anthony Meziere, Cendrine Tourette, Christian Neri, Marc Verny, Bruno Riou, Frederic Khiami, Jacques Boddaert
Association between Cognitive Status before Surgery and Outcomes in Elderly Patients with Hip Fracture in a Dedicated Orthogeriatric Care Pathway
Abstract: Background: Dementia is associated with a worse prognosis of hip fracture, but the impact of a dedicated geriatric care pathway on the prognosis of these patients has not been evaluated. Objective: According to the cognitive status before surgery, our main objective was to compare mortality rate at 6 months; secondary outcomes were to compare in-hospital complications, the risk of new institutionalization, and the ability to walk at 6 months. Methods: Between 2009 and 2015, all patients (>70 years) admitted after hip fracture surgery into a dedicated unit of peri-operative geriatric care were included: patients with dementia (DP), without dementia (NDP), and with cognitive status not determined (CSND). Data are expressed as hazard ratio (HR) for multivariate cox analysis or odds ratio (OR) for multivariate logistic regression analysis and their 95% confidence interval (CI). Results: We included 650 patients (86 ± 6 years): 168 DP, 400 NDP, and 82 CSND. After adjustment for age, sex, comorbidities, polypharmacy, pre-fracture autonomy, time-to-surgery, and delirium, there were no significant differences for 6-month mortality (DP versus NDP: HR=0.7[0.4 – 1.2], DP versus CSND: HR=0.6[0.3 – 1.4], CSND versus NDP: HR=0.8[0.4 – 1.7]); but DP and CSND were more likely to be newly institutionalized after 6 months compared to NDP (OR DP=2.6[1.4 – 4.9], p=0.003, OR CSND=2.9[1.4 – 6.1], p=0.004). 92% of population was walking after 6 months (63% with assistance): no difference was found between the three groups. Conclusion: In a dedicated geriatric care pathway, DP and CSND undergoing hip surgery have the same 6-month mortality and walking ability as NDP.
Joyce R. Chong, Yuek Ling Chai, Jasinda H. Lee, David Howlett, Johannes Attems, Clive G. Ballard, Dag Aarsland, Paul T. Francis, Christopher P. Chen, Mitchell K.P. Lai
Increased Transforming Growth Factor β2 in the Neocortex of Alzheimer’s Disease and Dementia with Lewy Bodies is Correlated with Disease Severity and Soluble Aβ42 Load
Abstract: Background: Of the three transforming growth factor (TGF)-β isoforms known, TGFβ1 deficits have been widely reported in Alzheimer’s disease (AD) and studied as a potential therapeutic target. In contrast, the status of TGFβ2, which has been shown to mediate amyloid-β (Aβ)-mediated neuronal death, are unclear both in AD and in Lewy body dementias (LBD) with differential neuritic plaque and neurofibrillary tangle burden. Objective: To measure neocortical TGFβ2 levels and their correlations with neuropathological and clinical markers of disease severity in a well-characterized cohort of AD as well as two clinical subtypes of LBD, dementia with Lewy bodies (DLB) and Parkinson’s disease dementia (PDD), known to manifest relatively high and low Aβ plaque burden, respectively. Methods: Postmortem samples from temporal cortex (BA21) were measured for TGFβ2 using a Luminex-based platform, and correlated with scores for neuritic plaques, neurofibrillary tangles, α-synuclein pathology, dementia severity (as measured by annual decline of Mini-Mental State Examination scores) as well as soluble and total fractions of brain Aβ42. Results: TGFβ2 was significantly increased in AD and DLB, but not in PDD. TGFβ2 also correlated with scores for neurofibrillary tangles, Lewy bodies (within the LBD group), dementia severity, and soluble Aβ42 concentration, but not with neuritic plaque scores, total Aβ42, or monomeric α-synuclein immunoreactivity. Conclusions: TGFβ2 is increased in the temporal cortex of AD and DLB, and its correlations with neuropathological and clinical markers of disease severity as well as with soluble Aβ42 load suggest a potential pathogenic role in mediating the neurotoxicity of non-fibrillar Aβ. Our study also indicates the potential utility of targeting TGFβ2 in pharmacotherapeutic approaches to AD and DLB.
Matthew Heath, Erin Shellington, Sam Titheridge, Dawn P. Gill, Robert J. Petrella (Handling Associate Editor: Krista Lanctôt)
A 24-Week Multi-Modality Exercise Program Improves Executive Control in Older Adults with a Self-Reported Cognitive Complaint: Evidence from the Antisaccade Task
Abstract: Exercise programs involving aerobic and resistance training (i.e., multiple-modality) have shown promise in improving cognition and executive control in older adults at risk, or experiencing, cognitive decline. It is, however, unclear whether cognitive training within a multiple-modality program elicits an additive benefit to executive/cognitive processes. This is an important question to resolve in order to identify optimal training programs that delay, or ameliorate, executive deficits in persons at risk for further cognitive decline. In the present study, individuals with a self-reported cognitive complaint (SCC) participated in a 24-week multiple-modality (i.e., the M2 group) exercise intervention program. In addition, a separate group of individuals with a SCC completed the same aerobic and resistance training as the M2 group but also completed a cognitive-based stepping task (i.e., multiple-modality, mind-motor intervention: M4 group). Notably, pre- and post-intervention executive control was examined via the antisaccade task (i.e., eye movement mirror-symmetrical to a target). Antisaccades are an ideal tool for the study of individuals with subtle executive deficits because of its hands- and language-free nature and because the task’s neural mechanisms are linked to neuropathology in cognitive decline (i.e., prefrontal cortex). Results showed that M2 and M4 group antisaccade reaction times reliably decreased from pre- to post-intervention and the magnitude of the decrease was consistent across groups. Thus, multi-modality exercise training improved executive performance in persons with a SCC independent of mind-motor training. Accordingly, we propose that multiple-modality training provides a sufficient intervention to improve executive control in persons with a SCC.
Sylwia W. Brooks, Ava C. Dykes, Bernard G. Schreurs (Handling Associate Editor: Othman Ghribi)
A High-Cholesterol Diet Increases 27-Hydroxycholesterol and Modifies Estrogen Receptor Expression and Neurodegeneration in Rabbit Hippocampus
Abstract: Hypercholesterolemia has been implicated in numerous health problems from cardiovascular disease to neurodegeneration. High serum cholesterol levels in midlife have been associated with an increased risk of developing Alzheimer’s disease (AD) later in life which suggests that the pathways leading to AD pathology might be activated decades before the symptoms of the disease are detected. Cholesterol-fed animals, particularly cholesterol-fed rabbits, exhibit brain pathology similar to the changes found in brains of AD patients. Dietary cholesterol, which cannot pass the blood-brain barrier, is thought to influence central nervous system homeostasis by increased transport of its circulatory breakdown product, 27-hydroxycholesterol (27-OHC), into the brain. 27-OHC is an endogenous selective estrogen receptor modulator. Estrogen-mediated non-reproductive functions require estrogen receptors (ERs) and include modulation of mitochondrial function and structure, as well as regulation of synaptogenesis in the brain. ERs are located in brain areas affected early in AD pathogenesis, including the hippocampus. Here we report that increase in serum cholesterol, induced by feeding rabbits a high-cholesterol diet, is associated with higher levels of 27-OHC in the brain as well as increased levels of neurodegeneration in the hippocampus. Furthermore, these results are accompanied by changes in expression of ERs in the hippocampus as well as a decrease in hippocampal mitochondria. These findings provide an important insight into one of the possible mechanisms involved in the development of AD, and shed light on the processes that may antedate amyloid-β and tau phosphorylation changes currently hypothesized to cause AD symptomology and pathology.
Ivayla Apostolova, Catharina Lange, Anna Roberts, Hans Joachim Igel, Anja Mäurer, Stephanie Liese, Melanie Estrella, Vikas Prasad, Elisabeth Stechl, Gernot Lämmler, Elisabeth Steinhagen-Thiessen, Ralph Buchert (Handling Associate Editor: Babak Ardekani)
Challenges in Screening and Recruitment for a Neuroimaging Study in Cognitively Impaired Geriatric Inpatients
Abstract: Background: Neuroimaging-based biomarkers have the potential to improve etiological diagnosis of cognitive impairment in elderly inpatients. However, there is a relative lack of studies on neuroimaging-based biomarkers in hospitalized geriatric patients, as the vast majority of neuroimaging studies in dementia have focused on memory clinic outpatients. An important aspect of study planning is a priori estimation of the rate of screen failures. Objective: To report on the rate and causes of screen failures in a prospective study on the utility of neuroimaging (PET, MRI) for the etiological diagnosis of newly manifested cognitive impairment in acutely hospitalized geriatric patients. Methods: Ten acute care geriatrics clinics with 802 beds participated in the study. The potential recruitment rate had been estimated to 5 patients/100 beds/week. Results: Seventeen months of pre-screening resulted in 322 potential participants. 109 of these patients were enrolled, i.e., the screen failure rate was 66%. 58% of the screen failures were due to refusal of participation by the patient, most often due to lack of interest in clarifying the cause of the cognitive impairment or due to reluctance to engage in additional diagnostic procedures associated with physical stress. 42% of pre-screened patients were excluded because of violation of the eligibility criteria. Conclusion: Enrollment for neuroimaging studies presents considerable additional challenges in acutely hospitalized geriatric patients compared to outpatient settings. Low rate of approaching potential candidates by attending geriatricians and a high rate of screen failures have to be anticipated in the study design.
Charles Agyemang, Irene E. van de Vorst, Huiberdina L. Koek, Michiel L. Bots, Azizi Seixas, Marie Norredam, Umar Ikram, Karien Stronks, Ilonca Vaartjes
Ethnic Variations in Prognosis of Patients with Dementia: A Prospective Nationwide Registry Linkage Study in The Netherlands
Abstract: Background: Data on dementia prognosis among ethnic minority groups are limited in Europe. Objective: We assessed differences in short-term (1-year) and long-term (3-year) mortality and readmission risk after a first hospitalization or first ever referral to a day clinic for dementia between ethnic minority groups and the ethnic Dutch population in the Netherlands. Methods: Nationwide prospective cohorts of first hospitalized dementia patients (N=55,827) from January 1, 2000 to December 31, 2010 were constructed. Differences in short-term and long-term mortality and readmission risk following hospitalization or referral to the day clinic between ethnic minority groups (Surinamese, Turkish, Antilleans, Indonesians) and the ethnic Dutch population were investigated using Cox proportional hazard regression models with adjustment for age, sex, and comorbidities. Results: Age-sex-adjusted short-term and long-term risks of death following a first hospitalization with dementia were comparable between the ethnic minority groups and the ethnic Dutch. Age- and sex-adjusted risk of admission was higher only in Turkish compared with ethnic Dutch (HR 1.57, 95% CI,1.08-2.29). The difference between Turkish and the Dutch attenuated and was no longer statistically significant after further adjustment for comorbidities. There were no ethnic differences in short-term and long-term risk of death, and risk of readmission among day clinic patients. Conclusion: Compared with Dutch patients with a comparable comorbidity rate, ethnic minority patients with dementia did not have a worse prognosis. Given the poor prognosis of dementia, timely and targeted advance care planning is essential, particularly in ethnic minority groups who are mired by cultural barriers and where uptake of advance care planning is known to be low.
Kaarin J. Anstey, Kimberly Ashby-Mitchell, Ruth Peters
Updating the Evidence on the Association between Serum Cholesterol and Risk of Late-Life Dementia: Review and Meta-Analysis
Abstract: Background: Cohort studies have reported that midlife high total serum cholesterol (TC) is associated with increased risk of Alzheimer’s disease (AD) in late-life but findings have been based on few studies and previous reviews have been limited by a lack of compatible data. Objective: We synthesized all high quality data from cohort studies reporting on the association between total serum cholesterol measured and late-life cognitive outcomes including Alzheimer’s disease (AD), vascular dementia (VaD), any dementia, mild cognitive impairment (MCI), and cognitive decline. Methods: The literature was searched up to October 2016 using a registered protocol. Thirty-four articles meeting study criteria were identified. Seventeen studies published from 1996 to 2014, including 23,338 participants were included in meta-analyses. Results: Relative risk of developing AD for adults with high TC in midlife was 2.14 (95% CI 1.33-3.44) compared with normal cholesterol. Individual studies that could not be pooled also reported high TC in midlife increased the risk of MCI and cognitive decline in late-life. High TC in late-life was not associated with MCI, AD, VaD, any dementia, or cognitive decline. Late-life measured HDL cholesterol and triglycerides were not associated with increased risk of VaD, and HDL was not associated with risk of MCI, AD, or any dementia. There were insufficient data to examine other cholesterol sub-fractions, sex differences, or APOE interactions. Conclusions: Significant gaps in the literature regarding TC and late-life dementia remain. Evidence suggests that high midlife TC increases risk of late-life AD, and may correlate with the onset of AD pathology.
Sophie Sokolow, Xiaohui Li, Lucia Chen, Kent D. Taylor, Jerome I. Rotter, Robert A. Rissman, Paul S. Aisen, Liana G. Apostolova (Handling Associate Editor: Beatrice Arosio)
Deleterious Effect of Butyrylcholinesterase K-Variant in Donepezil Treatment of Mild Cognitive Impairment
Abstract: Background: Donepezil is an acetylcholinesterase inhibitor frequently prescribed for the treatment of mild cognitive impairment (MCI) though not approved by the Food and Drug Administration for this indication. In Alzheimer’s disease, butyrylcholinesterase (BChE) activity increases with disease progression and may replace acetylcholinesterase function. The most frequent polymorphism of BChE is the K-variant, which is associated with lower acetylcholine-hydrolyzing activity. BChE-K polymorphism has been studied in Alzheimer’s disease progression and donepezil therapy, and has led to contradictory results. Objectives: To determine whether BChE-K genotype predicts response to donepezil in MCI. Methods: We examined the association between BChE-K genotype and changes in cognitive function using the data collected during the ADCS vitamin E/donepezil clinical trial in MCI. Results: We found significant interactions between BChE-K genotype and the duration of donepezil treatment, with increased changes in MMSE and CDR-SB scores compared to the common allele in MCI subjects treated during the 3-year trial. We found faster MMSE decline and CDR-SB rise in BChE-K homozygous individuals treated with donepezil compared to the untreated. We observed similar interactions between BChE-K genotype and steeper changes in MMSE and CDR-SB scores in APOE4 carriers treated with donepezil compared to controls. Conclusion: BChE-K polymorphisms are associated with deleterious changes in cognitive decline in MCI patients treated with donepezil for 3 years. This indicates that BChE-K genotyping should be performed to help identify subsets of subjects at risk for donepezil therapy, like those carrying APOE4. BChE-K and APOE4 carriers should not be prescribed off-label donepezil therapy for MCI management.
Virginia Boccardi*, Marta Baroni*, Nicoletta Smirne, Alessandra Clodomiro, Sara Ercolani, Annalisa Longo, Carmelinda Ruggiero, Amalia C. Bruni, Patrizia Mecocci (Handling Associate Editor: Domenico Pratico) *These authors contributed equally to this work.
Short-Term Response is not Predictive of Long-Term Response to Acetylcholinesterase Inhibitors in Old Age Subjects with Alzheimer’s Disease: A “Real World” Study
Abstract: Background: Most of clinical guidelines recommend discontinuing treatment with cholinesterase inhibitors (ChEIs) in patients with Alzheimer’s disease (AD) who do not show an initial response to therapy as evaluated with the Mini-Mental State Examination (MMSE) scale. However, understanding the relationship between the initial response to ChEI treatment and the subsequent course of the disease is extremely important in clinical practice, but evidence is limited, particularly in the old-old population. Objective: We aimed at investigating the relationship between short-term and long-term response to ChEI therapy in old age subjects with AD in a “real life” setting. Methods: This is a retrospective longitudinal study of 628 old age subjects (≥65 years old) with AD and treated with ChEIs over three year follow-up. The sample was divided into “young-old” (≤75 years) and “old-old” (≥76 years) according to age, and as “responder” and “non-responder” according to the initial (i.e., after three months) response to treatment. Cognitive and functional evaluation was performed by means of MMSE and ADL/IADL, respectively. Results: In the long run, subjects considered as non-responders showed a lower rate of cognitive decline as compared with responders, with a mean annual decline at MMSE of 1.0 point versus 1.6 points (p <0.0001), respectively. Old-old non-responders had a slower rate of cognitive (p <0.0001) and functional decline (p <0.0001) as compared with responders after three years of observation. Conclusion: Discontinuing ChEI treatment solely for the absence of an initial response is not appropriate, especially in old-old subjects.
Lisa D. Van Mierlo, Hans Wouters, Sietske A.M. Sikkes, Wiesje M. Van der Flier, Niels D. Prins, Jonne A.E. Bremer, Teddy Koene, Hein P.J. Van Hout
Screening for Mild Cognitive Impairment and Dementia with Automated, Anonymous Online and Telephone Cognitive Self-Tests
Abstract: Background: Many older people worry about cognitive decline. Early cognitive screening in an anonymous and easily accessible manner may reassure older people who are unnecessarily worried about normal cognitive aging while it may also expedite help seeking in case of suspicious cognitive decline. Objective: To develop and validate online and telephone-based automated self-tests of cognitive function. Methods: We examined the feasibility and validity of the self-tests in a prospective study of 117 participants of whom 34 had subjective cognitive decline (SCD), 30 had mild cognitive impairment (MCI), and 53 had dementia. The ability of these self-tests to accurately distinguish MCI and dementia from SCD was examined with ROC curves. Convergent validity was examined by calculating rank correlations between the self-tests and neuropsychological tests. Results: Both the online and telephone cognitive self-tests were feasible, because the majority of participants (86% and 80%, respectively) were able to complete them. The online self-test had adequate diagnostic accuracy in the screening for MCI and dementia versus SCD with an Area under the Curve (AUC) of 0.86 (95%CI: 0.78-0.93). The AUC of the MMSE was 0.82 (95%CI: 0.74-0.89). By contrast, the telephone self-test had lower diagnostic accuracy (AUC = 0.75, 95%CI: 0.64-0.86). Both self-tests had good convergent validity as demonstrated by moderate to strong rank correlations with neuropsychological tests. Conclusion: We demonstrated good diagnostic accuracy and convergent validity for the online self-test of cognitive function. It is therefore a promising tool in the screening for MCI and dementia.
Daniel G. Amen, Borhan Darmal, Cyrus A. Raji, Weining Bao, Lantie Jorandby, Somayeh Meysami, Cauligi S. Raghavendra
Discriminative Properties of Hippocampal Hypoperfusion in Marijuana Users Compared to Healthy Controls: Implications for Marijuana Administration in Alzheimer’s Dementia
Abstract: Background: Few studies have evaluated the impact of marijuana use on regional cerebral blood flow. Objective: To determine whether perfusion in specific brain regions on functional neuroimaging, including those affected by Alzheimer’s disease pathology, are abnormal in marijuana users compared to controls. Method: Persons with a diagnosis of cannabis use disorder by DSM-IV and DSM-V criteria (n=982) were compared to controls (n=92) with perfusion neuroimaging with SPECT at rest and at a concentration task. Perfusion estimates were quantified using a standard atlas. Cerebral perfusion differences were calculated using one-way ANOVA. Diagnostic separation was determined with discriminant analysis of all subjects. Feature selection with a minimum redundancy maximum relevancy (mRMR) identified predictive regions in a subset of marijuana users (n = 436) with reduced psychiatric co-morbidities. Results: Marijuana users showed lower cerebral perfusion on average (p < 0.05). Discriminant analysis distinguished marijuana users from controls with correct classification of 96% and leave one out cross-validation of 92%. With concentration SPECT regions, there was correct classification of 95% with a leave-one-out cross validation of 90%. AUC analysis for concentration SPECT regions showed 95% accuracy, 90% sensitivity, and 83% specificity. The mRMR analysis showed right hippocampal hypoperfusion on concentration SPECT imaging was the most predictive in separating marijuana subjects from controls. Conclusion: Multiple brain regions show low perfusion on SPECT in marijuana users. The most predictive region distinguishing marijuana users from healthy controls, the hippocampus, is a key target of Alzheimer’s disease pathology. This study raises the possibility of deleterious brain effects of marijuana use.
Nicole Last, Emily Tufts, Leslie E. Auger
The Effects of Meditation on Grey Matter Atrophy and Neurodegeneration: A Systematic Review
Abstract: The present systematic review is based on the premise that a variety of neurodegenerative diseases are accompanied by grey matter atrophy in the brain and meditation may impact this. Given that age is a major risk factor for many of these progressive and neurodegenerative diseases and that the percentage of the population over the age of 65 is quickly increasing, there is an obvious need for prompt treatment and prevention advances in research. As there is currently no cure for Alzheimer's disease and other neurodegenerative diseases, many are seeking non-pharmacological treatment options in attempts to offset the disease-related cognitive and functional declines. On the basis of a growing body of research suggesting that meditation is effective in increasing grey matter volume in healthy participants, this paper systematically reviewed the literature regarding the effects of meditation on restoring grey matter volume in healthy individuals and those affected by neurodegeneration. This review searched PubMed, CINAHL, and APA PsycNET to identify original studies that included MRI imaging to measure grey matter volume in meditators and post-mindfulness-based intervention participants compared to controls. Thirteen studies were considered eligible for review and involved a wide variety of meditation techniques and included participants with and without cognitive impairment. All studies reported significant increases in grey matter volume in the meditators/intervention group, albeit in assorted regions of the brain. Limited research exists on the mechanisms through which meditation affects disease-related neurodegeneration, but preliminary evidence suggests that it may offset grey matter atrophy.
Tanya Glozman, Justin Solomon, Franco Pestilli, Leonidas Guibas, for the Alzheimer’s Disease Neuroimaging Initiative (Handling Associate Editor: Yudong Zhang)
Shape-Attributes of Brain Structures as Biomarkers for Alzheimer's Disease
Abstract: We describe a fully automatic framework for classification of two types of dementia based on the differences in the shape of brain structures. We consider Alzheimer's disease (AD), mild cognitive impairment of individuals who converted to AD within 18 months (MCIc), and normal controls (NC). Our approach uses statistical learning and a feature space consisting of projection-based shape descriptors, allowing for canonical representation of brain regions. Our framework automatically identifies the structures most affected by the disease. We evaluate our results by comparing to other methods using a standardized data set of 375 adults available from the Alzheimer's Disease Neuroimaging Initiative (ADNI). Our framework is sensitive to identifying the onset of Alzheimer's disease, achieving up to 88.13% accuracy in classifying MCIc versus NC, outperforming previous methods.
Barbara Fenesi, Hanna Fang, Ana Kovacevic, Mark Oremus, Parminder Raina, Jennifer J. Heisz (Handling Associate Editor: Jeff Burns)
Physical Exercise Moderates the Relationship of Apolipoprotein E (APOE) Genotype and Dementia Risk: A Population-Based Study
Abstract: Genetics and lifestyle independently determine dementia risk, but the interaction is unclear. We assessed the interactive relationship of apolipoprotein E (APOE) genotype and physical exercise on dementia risk over a 5-year period in 1,646 older adults from the Canadian Study of Health and Aging who were dementia-free at baseline. Physical exercise moderated the relationship between genotype and dementia (p < 0.01). Specifically, for APOE ε4 non-carriers, the odds of developing dementia were higher in non-exercisers than exercisers (OR=1.98, 95% CI=1.44, 2.71, p < 0.001), whereas, for APOE ε4 carriers, the odds of developing dementia were not significantly different between non-exercisers and exercisers (OR=0.71, 95% CI=0.46, 1.31, p = 0.34). Given that most individuals are not at genetic risk, physical exercise may be an effective strategy for preventing dementia.
Lap Ho, Marc Legere, Tongbin Li, Samara Levine, Ke Hao, Breanna Valcarcel, Giulio M. Pasinetti
Autonomic Nervous System Dysfunctions as a Basis for a Predictive Model of Risk of Neurological Disorders in Subjects with Prior History of Traumatic Brain Injury: Implications in Alzheimer’s Disease
Abstract: Autonomic dysfunction is very common in patients with dementia, and its presence might also help in differential diagnosis among dementia subtypes. Various central nervous system structures affected in Alzheimer's disease (AD) are also implicated in the central autonomic nervous system (ANS) regulation. For example, deficits in central cholinergic function in AD could likely lead to autonomic dysfunction. We recently developed a simple, readily applicable evaluation for monitoring ANS disturbances in response to traumatic brain injury (TBI). This ability to monitor TBI allows for the possible detection and targeted prevention of long-term, detrimental brain responses caused by TBI that lead to neurodegenerative diseases such as AD. We randomly selected and extracted de-identified medical record information from subjects who have been assessed using the ANS evaluation protocol. Using machine learning strategies in the analysis of information from individual as well as a combination of ANS evaluation protocol components, we identified a novel prediction model that is effective in correctly segregating between cases with or without a documented history of TBI exposure. Results from our study support the hypothesis that trauma-induced ANS dysfunctions may contribute to clinical TBI features. Because autonomic dysfunction is very common in AD patients it is possible that TBI may also contribute to AD and/or other forms of dementia through these novel mechanisms. This study provides a novel prediction model to physiologically assess the likelihood of subjects with prior history of TBI to develop clinical TBI complications, such as AD.
Ivana Jurjević, Masakazu Miyajima, Ikuko Ogino, Chihiro Akiba, Madoka Nakajima, Akihide Kondo, Mika Kikkawa, Mitsuyasu Kanai, Nobutaka Hattori5 Hajime Arai (Handling Associate Editor: Helen Wu)
Decreased Expression of hsa-miR-4274 in Cerebrospinal Fluid of Normal Pressure Hydrocephalus Mimics with Parkinsonian Syndromes
Abstract: Background: Patients presenting with the classical idiopathic normal pressure hydrocephalus (iNPH) triad often show additional parkinsonian spectrum signs. Accurate differential diagnosis strongly influences the long-term outcome of cerebrospinal fluid (CSF) shunting. Objective: The aim of this study was to find potential CSF microRNA (miRNA) biomarkers for NPH mimics with parkinsonian syndromes that can reliably distinguish them from iNPH patients. Methods: Two cohorts of 81 patients (cohort 1, n=55; cohort 2, n=26) with possible iNPH who were treated in two centers between January 2011 and May 2014 were studied. In both cohorts, CSF samples were obtained from patients clinically diagnosed with iNPH (n=21 and n=10, respectively), possible iNPH with parkinsonian spectrum (PS) (n=18, n=10, respectively), possible iNPH with Alzheimer’s disease (AD) (n=16), and non-affected elderly individuals (NC) (n=6). A three-step qRT-PCR analysis of the CSF samples was performed to detect miRNAs that were differentially expressed in the groups. Results The expression of hsa-miR-4274 in CSF was decreased in both cohorts of PS group patients (cohort 1: p<0.0001, cohort 2: p<0.0001), and was able to distinguish PS from iNPH with high accuracy (area under the curve=0.908). The CSF concentration of hsa-miR-4274 also correlated with the specific binding ratio of ioflupane (123I) dopamine transporter scan (r=−0.494, p=0.044). By contrast, the level of hsa-miR-4274 was significantly increased in the PS group after CSF diversion. Conclusion Levels of CSF hsa-miR-4274 can differentiate PS from patients with iNPH, AD, and NC. This may be clinically useful for diagnostic purposes and predicting shunt treatment responses.
Xiaozhen Li, Eric Westman, Steinunn Thordardottir, Anne Kinhult Ståhlbom, Ove Almkvist, Kaj Blennow, Lars-Olof Wahlund, Caroline Graff
The Effects of Gene Mutations on Default Mode Network in Familial Alzheimer’s Disease
Abstract: Familial Alzheimer’s disease (FAD) mutations have very high penetrance but age at onset and rate of disease progression differ. Neuroimaging and cerebrospinal fluid (CSF) examinations in mutation carriers (MCs) may provide an opportunity to identify early biomarkers that can be used to track disease progression from presymptomatic to the dementia stages of disease. The default mode network (DMN) is a resting state neuronal network composed of regions known to associate with amyloid deposition in AD. We hypothesized that functional connectivity in the DMN might change at pre-clinical stages in FAD MCs and correlate with changes in CSF biomarkers as a consequence of AD brain pathology. To test the hypothesis, we compared the functional connectivity in DMN between pre-MCs/MCs and non-carriers (NCs). No significant differences between pre-MCs and NCs were observed. When comparing all MCs with NCs, significant decreased functional connectivity in the right inferior parietal lobule, right precuneus, and left posterior cingulate cortex were found. We also found statistically significant correlations between CSF amyloid-β 42 and tau protein levels and average Z-score, a resting-state functional MRI measurement reflecting the degree of the correlation between a given voxel’s time courses and the time courses corresponding to DMN, from the region with statistical difference. The observed disruption of DMN and pathological levels of AD CSF-biomarkers in FAD MCs are similar to the changes described in sporadic AD, which give further support that amyloid and tau pathology impairs neuronal and synaptic function.
Varsha Shukla, Jinsoo Seo, Binukumar BK, Niranjana D. Amin, Preethi Reddy, Philip Grant, Susan Kuntz, Sashi Kesavapany, Joseph Steiner, Santosh K. Mishra, Li-Huei Tsai, Harish C. Pant
TFP5, a Peptide Inhibitor of Aberrant and Hyperactive Cdk5/p25, Attenuates Pathological Phenotypes and Restores Synaptic Function in CK-p25Tg Mice
Abstract: It has been reported that cyclin-dependent kinase 5 (cdk5), a critical neuronal kinase, is hyperactivated in Alzheimer’s disease (AD) and may be, in part, responsible for the hallmark pathology of amyloid plaques and neurofibrillary tangles (NFTs). It has been proposed by several laboratories that hyperactive cdk5 results from the overexpression of p25 (a truncated fragment of p35, the normal cdk5 regulator), which, when complexed to Cdk5, induces hyperactivity, hyperphosphorylated tau/NFTs, amyloid-β plaques, and neuronal death. It has previously been shown that intraperitoneal (i.p.) injections of a modified truncated 24-aa peptide (TFP5), derived from the cdk5 activator p35, penetrated the blood-brain barrier and significantly rescued AD-like pathology in 5XFAD model mice. The principal pathology in the 5XFAD mutant, however, is extensive amyloid plaques; hence, as a proof of concept, we believe it is essential to demonstrate the peptide’s efficacy in a mouse model expressing high levels of p25, such as the inducible CK-p25Tg model mouse that overexpresses p25 in CamKII positive neurons. Using a modified TFP5 treatment, here we show that peptide i.p. injections in these mice decrease cdk5 hyperactivity, tau, neurofilament-M/H hyperphosphorylation, and restore synaptic function and behavior (i.e., spatial working memory, motor deficit using Rota-rod). It is noteworthy that TFP5 does not inhibit endogenouscdk5/p35 activity, nor other cdks in vivo suggesting it might have no toxic side effects, and may serve as an excellent therapeutic candidate for neurodegenerative disorders expressing abnormally high brain levels of p25 and hyperactive cdk5.
Lena L. Law, Stephanie A. Schultz, Elizabeth A. Boots, Jean A. Einerson, Ryan J. Dougherty, Jennifer M. Oh, Claudia E. Korcarz, Dorothy F. Edwards, Rebecca L. Koscik, N. Maritza Dowling, Catherine L. Gallagher, Barbara B. Bendlin, Cynthia M. Carlsson, Sanjay Asthana, Bruce P. Hermann, Mark A. Sager, Sterling C. Johnson, Dane B. Cook, James H. Stein, Ozioma C. Okonkwo (Handling Associate Editor: Jeff Burns)
Chronotropic Response and Cognitive Function in a Cohort at Risk for Alzheimer’s Disease
Abstract: The objective of this study was to examine the association of chronotropic response (CR) and heart rate (HR) recovery—two indices of cardiovascular function within the context of a graded exercise test—with cognitive performance in a cognitively healthy, late-middle-aged cohort at risk for Alzheimer’s disease (AD). Ninety participants (age=63.52±5.86 years; 65.6% female) from the Wisconsin Registry for Alzheimer’s Prevention participated in this study. They underwent graded exercise testing and a comprehensive neuropsychological assessment that assessed the following four cognitive domains: Immediate Memory, Verbal & Learning Memory, Working Memory, and Speed & Flexibility. Regression analyses, adjusted for age, sex, and education, were used to examine the association between CR, HR recovery, and cognition. We found significant associations between CR and cognitive performance in the domains of Immediate Memory, Verbal Learning & Memory, and Speed & Flexibility. In contrast, HR recovery was not significantly associated with cognitive function. The association between CR and cognition persisted even after controlling for HR recovery. Together, these findings indicate that, in a cognitively normal, late-middle-aged cohort, CR is a stronger correlate of cognitive performance than HR recovery. Overall, this study reinforces the idea that cardiovascular health plays an important role in cognitive function, specifically in a cohort at risk for AD; and that interventions that promote vascular health may be a viable pathway to preventing or slowing cognitive decline due to AD.
Liming Shen, Liping Liao, Cheng Chen, Yi Guo, Dalin Song, Yong Wang, Youjiao Chen, Kaoyuan Zhang, Ming Ying, Shuiming Li, Qiong Liu, Jiazuan Ni
Proteomics Analysis of Blood Serums from Alzheimer’s Disease Patients Using iTRAQ Labeling Technology
Abstract: Alzheimer’s disease (AD) is the most common form of dementia affecting up to 6% of the population over the age of 65. In order to discover differentially expressed proteins that might serve as potential biomarkers, the serums from AD patients and healthy controls were compared and analyzed using the proteomics approach of isobaric tagging for relative and absolute quantitation (iTRAQ). For the first time, AD biomarkers in serums are investigated in the Han Chinese population using iTRAQ labeled proteomics strategy. Twenty-two differentially expressed proteins were identified and out of which nine proteins were further validated with more sample test. Another three proteins that have been reported in the literature to be potentially associated with AD were also investigated for alteration in expression level. Functions of those proteins were mainly related to the following processes: amyloid-β (Aβ) metabolism, cholesterol transport, complement and coagulation cascades, immune response, inflammation, hemostasis, hyaluronan metabolism, and oxidative stress. These results support current views on the molecular mechanism of AD. For the first time, differential expression of zinc-alpha-2-glycoprotein (AZGP1), fibulin-1 (FBLN1), platelet basic protein (PPBP), thrombospondin-1 (THBS1), S100 calcium-binding protein A8 (S100A8), and S100 calcium-binding protein A9 (S100A9) were detected in the serums of AD patients compared with healthy controls. These proteins might play a role in AD pathophysiology and serve as potential biomarkers for AD diagnosis. Specifically, our results strengthened the crucial role of Aβ metabolism and blood coagulation in AD pathogenesis and proteins related to these two processes may be used as peripheral blood biomarkers for AD.
Louis Jacob, Jens Bohlken, Karel Kostev
Risk Factors for Mild Cognitive Impairment in German Primary Care Practices
Abstract: Background: Mild cognitive impairment (MCI) is a common mental disorder affecting around 16% of elderly people without dementia. MCI is considered an intermediate state between normal cognition and dementia. Objective: To analyze risk factors for the development of MCI in German primary care practices. Methods: In total, 3,604 MCI patients and 3,604 controls without MCI were included between January 2010 and December 2015. Several disorders potentially associated with MCI were determined. Multivariate logistic regression models were fitted with MCI as a dependent variable and other disorders as potential predictors. Results: The mean age was 75.2 years and 45.3% of patients were men. MCI development was found to be associated with 12 disorders: intracranial injury, anxiety disorder, depression, mental and behavioral disorders due to alcohol use, stroke, hyperlipidemia, obesity, hypertension, Parkinson’s disease, sleep disorder, coronary heart disease, and diabetes with odds ratios ranging from 1.13 (diabetes) to 2.27 (intracranial injury). Conclusion: Intracranial injury, anxiety, and depression showed the strongest association with MCI. Further analyses are needed to gain a better understanding of the MCI risk factors.
Liang Shen, Lu Liu, Hong-Fang Ji
Alzheimer’s Disease Histological and Behavioral Manifestations in Transgenic Mice Correlate with Specific Gut Microbiome State
Abstract: Alzheimer’s disease (AD) is a neurodegenerative brain disease and is the most common form of dementia. In recent years, many studies indicated the association of gut microbiota changes with metabolic diseases. However, the gut microbiota of AD has not been investigated. The present study aims to compare the gut microbiota in APP/PS1 transgenic mice of AD and C57/Bl6 wild-type (WT) mice by pyrosequencing the V3 and V4 regions of the bacterial 16S ribosomal RNA genes. The 3-, 6-, and 8-month-old APP/PS1 and WT mice were used to explore the effects of age on the gut microbiota. First, the results indicated that impaired spatial learning and memory appeared in 6-month-old APP/PS1 mice and was further aggravated in the 8-month-old group, which was consistent with immunohistochemical studies of amyloid plaque. Second, AD histological and behavioral manifestations in the APP/PS1 mice were found to be correlated with a specific gut microbiome state. Third, the microbiota diversity of APP/PS1 mice decreased with increased age. Fourth, further inspection showed that the abundance of Helicobacteraceae and Desulfovibrionaceae at the family level and Odoribacter and Helicobacter at the genus level increased significantly in APP/PS1 mice than in WT mice, while Prevotella abundance in WT mice was significantly higher than in APP/PS1 mice. More human studies are warranted to explore the potential of gut microbiota as diagnostic biomarkers or therapeutic target for AD.
Bing Xie*, Yao Xu*, Zanchao Liu, Wenxuan Liu, Lei Jiang, Rui Zhang, Dongsheng Cui, Qingfu Zhang, Shunjiang Xu (Handling Associate Editor: Ling-Qiang Zhu) *These authors contributed equally to this work.
Elevation of Peripheral BDNF Promoter Methylation Predicts Conversion from Amnestic Mild Cognitive Impairment to Alzheimer’s Disease: A 5-Year Longitudinal Study
Abstract: Epigenetic aberrations have been identified as biomarkers to predict the risk of Alzheimer's disease (AD). This study aimed to evaluate whether altered DNA methylation status of BDNF promoter could be used as potential epigenetic biomarkers for predicting the progression from amnestic mild cognitive impairment (aMCI) to AD. A total of 506 aMCI patients and 728 cognitively normal controls were recruited in the cross-sectional analyses. Patients (n = 458) from aMCI cohort were classified into two groups after 5-year follow-up: aMCI-stable group (n = 330) and AD-conversion group (n = 128). DNA methylation of BDNF promoter was detected by bisulfite-PCR amplification and pyrosequencing. The DNA methylation levels of CpG1 and CpG2 in promoter I and CpG5 and CpG6 in promoter IV of BDNF gene were significantly higher in the aMCI group than in the control group at baseline and also were increased in the conversion group compared with the non-conversion group at 5-year follow up time point. CpG5 in BDNF promoter IV had the highest AUC of 0.910 (95% CI: 0.817-0.983, p < 0.05). Kaplan-Meier analysis showed a significant AD conversion propensity for aMCI patients with high methylation levels of CpG5 (HR = 1.96, 95% CI: 1.07-2.98, p < 0.001). Multivariate Cox regression analysis revealed elevated methylation status of CpG5 was a significant independent predictor for AD conversion (HR = 3.51, p = 0.013). These results suggest that elevation of peripheral BDNF promoter methylation might be used as potential epigenetic biomarkers for predicting the conversion from aMCI to AD.
Kelsey E. McLimans*, Auriel A. Willette* *These authors contributed equally to this work.
Autotaxin is Related to Metabolic Dysfunction and Predicts Alzheimer’s Disease Outcomes
Abstract: Background: Obesity and insulin resistance are associated with neuropathology and cognitive decline in Alzheimer’s disease (AD). Objective: Ecto-nucleotide pyrophosphatase/phosphodiesterase 2, also called autotaxin, is produced by beige adipose tissue, regulates metabolism, and is higher in AD prefrontal cortex (PFC). Autotaxin may be a novel biomarker of dysmetabolism and AD. Methods: We studied Alzheimer’s Disease Neuroimaging Initiative participants who were cognitively normal (CN; n=86) or had mild cognitive impairment (MCI; n=135) or AD (n=66). Statistical analyses were conducted using SPSS software. Multinomial regression analyses tested if higher autotaxin was associated with higher relative risk for MCI or AD diagnosis, compared to the CN group. Linear mixed model analyses were used to regress autotaxin against MRI, FDG-PET, and cognitive outcomes. Spearman correlations were used to associate autotaxin and CSF biomarkers due to non-normality. FreeSurfer 4.3 derived mean cortical thickness in medial temporal lobe and prefrontal regions of interest. Results: Autotaxin levels were significantly higher in MCI and AD. Each point increase in log-based autotaxin corresponded to a 3.5 to 5 times higher likelihood of having MCI and AD, respectively. Higher autotaxin in AD predicted hypometabolism in the medial temporal lobe [R2=0.343, p<0.001] and PFC [R2=0.294, p<0.001], and worse performance on executive function and memory factors. Autotaxin was associated with less cortical thickness in PFC areas like orbitofrontal cortex [R2=0.272, p<0.001], as well as levels of total tau, p-tau181, and total tau/Aβ1-42. Conclusions: These results are comparable to previous reports using insulin resistance. CSF autotaxin may be a useful dysmetabolism biomarker for examining AD outcomes and risk.
Zan Wang*, Zhengjia Dai*, Hao Shu, Duan Liu, Qihao Guo, Yong He, Zhijun Zhang *These authors contributed equally to this work.
Cortical Thickness and Microstructural White Matter Changes Detect Amnestic Mild Cognitive Impairment
Abstract: Both the apolipoprotein E (APOE) ε4 allele and amnestic mild cognitive impairment (aMCI) are considered to be risk factors for Alzheimer’s disease (AD). The primary aim of this study was to determine whether the aMCI-related abnormality in gray matter (GM) cortical thickness and white matter (WM) tracts integrity would be modified by the APOE genotype. A total of 146 older adults, including 64 aMCI patients (28 ε4 carriers and 36 non-carriers) and 82 healthy controls (39 ε4 carriers and 43 non-carriers), underwent a standardized clinical interview, neuropsychological battery assessment, and multi-modal brain magnetic resonance imaging scans. Compared with control subjects, the patients with aMCI showed significantly reduced cortical thickness bilaterally in the parahippocampal gyrus and disrupted WM integrity in the limbic tracts (e.g., increased mean diffusivity in the right parahippocampal cingulum and bilateral uncinate fasciculus). However, no significant main effect of the APOE genotype and diagnosis-by-genotype interaction on GM thickness and WM integrity were observed. Further, diffusivity measures of the limbic WM tracts were significantly correlated with the parahippocampal atrophy in aMCI. Importantly, the parahippocampal thickness and diffusivity measures of the limbic WM tracts were significantly correlated with the cognitive performance (i.e., episodic memory Z score) in patients with aMCI. These results demonstrate that WM microstructural disruptions in the limbic tracts are present at the early stage of AD in an APOE-independent manner; and this degeneration may occur progressively, in parallel with parahippocampal atrophy, and may specifically contribute to early initial impairment in episodic memory.