Pages 779-794
Review
Jeffrey L. Cummings, Gary Tong, Clive Ballard
Treatment Combinations for Alzheimer’s Disease: Current and Future Pharmacotherapy Options
Abstract: Although Alzheimer’s disease (AD) is the world’s leading cause of dementia and the population of patients with AD continues to grow, no new therapies have been approved in more than a decade. Many clinical trials of single-agent therapies have failed to affect disease progression or symptoms compared with placebo. The complex pathophysiology of AD may necessitate combination treatments rather than monotherapy. The goal of this narrative literature review is to describe types of combination therapy, review the current clinical evidence for combination therapy regimens (both symptomatic and disease-modifying) in the treatment of AD, describe innovative clinical trial study designs that may be effective in testing combination therapy, and discuss the regulatory and drug development landscape for combination therapy. Successful combination therapies in other complex disorders, such as human immunodeficiency virus, may provide useful examples of a potential path forward for AD treatment.
Pages 795-819
Review
Alberto Serrano-Pozo, John H. Growdon
Is Alzheimer’s Disease Risk Modifiable?
Abstract: Population-based clinic-pathological studies have established that the most common pathological substrate of dementia in community-dwelling elderly people is mixed, especially Alzheimer’s disease (AD) and cerebrovascular ischemic disease (CVID), rather than pure AD. While these could be just two frequent unrelated comorbidities in the elderly, epidemiological research has reinforced the idea that mid-life (age < 65 years) vascular risk factors increase the risk of late-onset (age ≥ 65 years) dementia, and specifically AD. By contrast, healthy lifestyle choices such as leisure activities, physical exercise, and Mediterranean diet are considered protective against AD. Remarkably, several large population-based longitudinal epidemiological studies have recently indicated that the incidence and prevalence of dementia might be decreasing in Western countries. Although it remains unclear whether these positive trends are attributable to neuropathologically definite AD versus CVID, based on these epidemiological data it has been estimated that a sizable proportion of AD cases could be preventable. In this review, we discuss the current evidence about modifiable risk factors for AD derived from epidemiological, preclinical, and interventional studies, and analyze the opportunities for therapeutic and preventative interventions.
Pages 821-826
Short Communication
Carolien Koop-Nieuwelink, Sanaz Sedaghat, Unal Mutlu, Silvan Licher, Oscar H. Franco, M. Arfan Ikram, Mirjam I. Geerlings, M. Kamran Ikram, Daniel Bos (Handling Associate Editor: Carol Brayne)
Kidney Function and the Risk of Stroke and Dementia: The Rotterdam Study
Abstract: Longitudinal population-based data on effects of kidney dysfunction in the development of stroke and dementia remains inconclusive. We investigated associations of kidney function with risk of stroke and dementia in 5,993 community-dwelling individuals (mean age: 69.0 years, 57.2% women). We calculated estimated glomerular filtration rates based on creatinine, cystatin-C, and a combination of these two. During a mean follow-up of 11.6 years (69,790 person-years), 1,360 individuals suffered a stroke (n=601) or developed dementia (n=759). We found that an impaired kidney function was related to a higher risk of stroke, but not to dementia.
Pages 827-837
Miri Lutski, Galit Weinstein, Uri Goldbourt*, David Tanne* (Handling Associate Editor: Amos Korczyn) *These authors contributed equally to this work.
Plasma Lipids, Apolipoproteins, and Subsequent Cognitive Decline in Men with Coronary Heart Disease
Abstract: Background: Lipid levels are associated with an increased risk of cardiovascular disease. Objective: We investigated the association between plasma lipids, apolipoproteins levels, apolipoprotein B/low-density lipoprotein cholesterol (Apo-B/LDL-C), and Apo-B/Apo-A ratios and rate of cognitive decline two decades later in men with coronary heart disease (CHD). Methods: A subset of 337 men (mean age at baseline 56.6±6.4 years) who previously participated in the Bezafibrate Infarction Prevention (BIP) trial (1990-1997) underwent cognitive evaluations 15±3 years (T1) and 19.9±1 years after baseline (T2) as part of the BIP Neurocognitive study. Lipid and apolipoprotein fractions were measured at baseline. Cognitive function for memory, executive function, visual spatial, attention domains, and composite score were assessed using the NeuroTrax Computerized Battery at T1 and T2 evaluations. Linear mixed models were used to assess change in cognitive function between the two cognitive evaluations. Results: Controlling for confounders, the decline in composite cognitive score (β=-0.161±0.06; p=0.013) as well as in memory (β=-0.269±0.10; p=0.009) and visual spatial function (β=-0.304±0.12; p=0.010) was greater among patients in the upper (≥105 mg/dL) Apo-B tertile as compared to counterparts with
Pages 839-848
Sonia Ben Jemaa, Yousri Marzouki, Mohamed Ben Fredj, Didier Le Gall, Tarek Bellaj (Handling Associate Editor: Robert Friedland)
The Adaptation and Validation of an Arabic Version of the Cornell Scale for Depression in Dementia (A-CSDD)
Abstract: Background: Depression is a major disorder that can be triggering, co-occurring, or exacerbating dementia symptoms. Its assessment is paramount to achieve diagnostic, prognostic, and therapeutic decisions. The Cornell Scale for Depression in Dementia (CSDD) is purposely designed to address clinically this issue. Objective: To examine the reliability and validity of an Arabic version of the CSDD (A-CSDD) in the Tunisian population. Methods: Fifty-seven participants took part in this study: 20 as a control group (NC), 18 as dementia patients with depression (DD), and 19 as depressed patients without dementia (DND); all patients met the DSM IV criteria for depression and/or dementia. A translated, back-translated and adapted Arabic version of the CSDD was administered in parallel with the Geriatric Depression Scale (GDS), the non-cognitive part of the Alzheimer's disease Assessment Scale, and the Mini-Mental State Examination. Results: The A-CSDD had good internal consistency (Cronbach’s alpha = 0.85) and high test-retest reliability (Rho=0.897, p<0.001). The A-CSDD had excellent discriminatory power to diagnose depression in dementia patients (AUC=0.90, p<0.001) and good concurrent validity with the GDS (Rho=0.70, p<0.001). A principal component analysis with varimax rotation, performed on the DD group, led to a configuration of five factors explaining 75% of the variance. Conclusions: The results showed that this Arabic-Tunisian version of the A-CSDD is reliable and valid for diagnosing depression in an elderly Tunisian population with dementia and can be used in clinical and research settings.
Pages 849-858
Karen Hornung*, Silvia Zampar*, Nadine Engel, Hans Klafki, Thomas Liepold, Thomas A. Bayer, Jens Wiltfang, Olaf Jahn, Oliver Wirths *These authors contributed equally to this work.
N-Terminal Truncated Aβ4-42 Is a Substrate for Neprilysin Degradation in vitro and in vivo
Abstract: In sporadic Alzheimer’s disease (AD), an imbalance between production and clearance of amyloid-β (Aβ) peptides seems to account for enhanced Aβ accumulation. The metalloprotease neprilysin (NEP) is an important Aβ degrading enzyme as shown by a variety of in vitro and in vivo studies. While the degradation of full-length Aβ peptides such as Aβ1-40 and Aβ1-42 is well established, it is less clear whether NEP is also capable of degrading N-terminally truncated Aβ species such as the common variant Aβ4-42. In the present report, we confirmed the degradation of Aβ4-x species by neprilysin using in vitro digestion and subsequent analysis using gel-based assays and mass spectrometry. By crossing Tg4-42 mice expressing only Aβ4-42 peptides with homozygous NEP-knock-out mice (NEP-/-), we were able to demonstrate that NEP deficiency increased hippocampal intraneuronal Aβ levels and aggravated neuron loss in the Tg4-42 transgenic mouse model of AD.
Pages 859-874
Donna J. Cross, James S. Meabon, Marcella M. Cline, Todd L. Richards, Amanda J. Stump, Chloe G. Cross, Satoshi Minoshima, William A. Banks, David G. Cook
Paclitaxel Reduces Brain Injury from Repeated Head Trauma in Mice
Abstract: Repetitive mild traumatic brain injury (rmTBI) is known to disturb axonal integrity and may play an important role in the pathogenic cascades leading to neurodegeneration. One critical approach to reduce the future onset of neurodegeneration is to intervene in this process at an early stage following a brain injury. Previously we showed that direct application of the microtubule-stabilizing drug, paclitaxel, on the brain following controlled cortical impact improved motor function and reduced lesion size. Herein, we extended these findings to a model of mild brain injury induced by repeated closed-skull impacts. Paclitaxel was administered intranasally to circumvent its poor transport across the blood-brain barrier. Mice received five mild closed-skull impacts (one per day for five days). Intranasal paclitaxel was administered once only, immediately after the first impact. We found that paclitaxel prevented injury-induced deficits in spatial memory task in a water tread maze. In vivo magnetic resonance imaging (MRI) and positron emission tomography with 18F-flurodeoxyglucose (FDG-PET) revealed that paclitaxel prevented structural injury and hypometabolism. On MRI, apparent, injury-induced microbleeds were observed in 100% of vehicle-treated rmTBI mice, but not in paclitaxel-treated subjects. FDG-PET revealed a 42% increase in whole brain glucose metabolism in paclitaxel-treated mice as compared to vehicle-treated rmTBI. Immunohistochemistry found reduced evidence of axonal injury and synaptic loss. Our results indicate that intranasal paclitaxel administration imparts neuroprotection against brain injury and cognitive impairment in mice. The results from this study support the idea that microtubule-stabilization strategies hold therapeutic promise in mitigating traumatic brain injury.
Pages 875-891
Jack T. Wiedrick, Jay I. Phillips, Theresa A. Lusardi, Trevor J. McFarland, Babett Lind, Ursula S. Sandau, Christina A. Harrington, Jodi A. Lapidus, Douglas R. Galasko, Joseph F. Quinn, Julie A. Saugstad (Handling Associate Editor: Robert Rissman)
Validation of MicroRNA Biomarkers for Alzheimer's Disease in Human Cerebrospinal Fluid
Abstract: We previously discovered microRNAs (miRNAs) in cerebrospinal fluid (CSF) that differentiate Alzheimer’s disease (AD) patients from Controls. Here we examined the performance of 37 candidate AD miRNA biomarkers in a new and independent cohort of CSF from 47 AD patients and 71 Controls on custom TaqMan® arrays. We employed a consensus ranking approach to provide an overall priority score for each miRNA, then used multimarker models to assess the relative contributions of the top-ranking miRNAs to differentiate AD from Controls. We assessed classification performance of the top-ranking miRNAs when combined with apolipoprotein E4 (APOE4) genotype status or CSF amyloid-β42 (Aβ42):total tau (T-tau) measures. We also assessed whether miRNAs that ranked higher as AD markers correlate with Mini-Mental State Examination (MMSE) scores. We show that of 37 miRNAs brought forth from the discovery study, 26 miRNAs remained viable as candidate biomarkers for AD in the validation study. We found that combinations of 6-7 miRNAs work better to identify AD than subsets of fewer miRNAs. Of 26 miRNAs that contribute most to the multimarker models, 14 have higher potential than the others to predict AD. Addition of these 14 miRNAs to APOE4 status or CSF Aβ42:T-tau measures significantly improved classification performance for AD. We further show that individual miRNAs that ranked higher as AD markers correlate more strongly with changes in MMSE scores. Our studies validate that a set of CSF miRNAs serve as biomarkers for AD, and support their advancement toward development as biomarkers in the clinical setting.
Pages 893-910
Bénédicte Foveau, Ana Sofia Correia, Sébastien S. Hébert, Sara Rainone, Olivier Potvin, Marie-Jeanne Kergoat, Sylvie Belleville, Simon Duchesne, Andréa C. LeBlanc and the CIMA-Q Consortium for the early identification of Alzheimer’s disease-Québec
Stem Cell-Derived Neurons as Cellular Models of Sporadic Alzheimer’s Disease
Abstract: Alzheimer’s disease (AD) occurs as either an autosomal dominant inherited disease or sporadically. While familial mutant genes can be expressed in cells or in animal models to assess dysregulated functions, sporadic AD cannot be replicated in models given our lack of understanding of causality. Furthermore, the study of sporadic forms of AD is difficult given the inaccessibility of brain tissues in living individuals and the manifestation of symptoms years after the onset of disease. Here, the objective was to assess if induced pluripotent stem cell-derived neurons from well-ascertained sporadic AD individuals could represent potential cellular models to determine the underlying molecular mechanisms of disease. We used cryopreserved peripheral blood mononuclear cells from three well-ascertained sporadic AD and three non-cognitively impaired (NCI) individuals of the CIMA-Q cohort to obtain iPSC-derived neurons. Microtubule associated protein 2 was decreased in AD neurons, whereas expression of AD-associated amyloid precursor protein, tau, and amyloid-β peptide was similar in AD and NCI individuals. RNA sequencing identified several upregulated and downregulated mRNAs in AD relative to NCI neurons. Of these, complement Factor H (CFH), signal regulatory protein beta1 (SIRPB1), and insulin like growth factor binding protein 5 (IGFBP5) were previously associated with AD. In addition, several transcription factors not previously associated with AD, but involved in neuronal proliferation and differentiation were differentially expressed. The results identify novel avenues for the study of the underlying causes of sporadic AD and support the establishment of additional lines to identify mechanisms of disease in sporadic AD individuals.
Pages 911-921
Alice L. La, Christine M. Walsh, Thomas C. Neylan, Keith A. Vossel, Kristine Yaffe, Andrew D. Krystal, Bruce L. Miller, Elissaios Karageorgiou
Long-Term Trazodone Use and Cognition: A Potential Therapeutic Role for Slow-Wave Sleep Enhancers
Abstract: Background: Recent studies reveal an association between slow-wave sleep (SWS), amyloid-β aggregation, and cognition. Objective: This retrospective study examines whether long-term use of trazodone, an SWS enhancer, is associated with delayed cognitive decline. Methods: We identified 25 regular trazodone users (mean age 75.4 ± 7.5; 9 women, 16 men) who carried a diagnosis of Alzheimer’s dementia, mild cognitive impairment, or normal cognition, and 25 propensity-matched trazodone non-users (mean age 74.5 ± 8.0; 13 women, 12 men), accounting for age, sex, education, type of sleep deficit (hypersomnia, insomnia, parasomnia), diagnosis, and baseline Mini-Mental State Examination (MMSE). Longitudinal group differences in cognitive testing were evaluated through repeated measures tests over an average inter-evaluation interval of four years. Results: Trazodone non-users had 2.6-fold faster decline MMSE (primary outcome) compared to trazodone users, 0.27 (95% confidence interval [CI]: 0.07–0.48) versus 0.70 (95% CI: 0.50–0.90) points per year (p = 0.023). The observed effects were especially associated with subjective improvement of sleep complaints in post-hoc analyses (p = 0.0006). Secondary outcomes of other cognitive and functional scores had variable worsening in non-users and varied in significance when accounting for co-administered medications and multiple comparisons. Trazodone effects on MMSE remained significant within participants with AD-predicted pathology, with 2.4-fold faster decline in non-users (p = 0.038). Conclusions: These results suggest an association between trazodone use and delayed cognitive decline, adding support for a potentially attractive and cost-effective intervention in dementia. Whether the observed relationship of trazodone to cognitive function is causal or an indirect marker of other effects, such as treated sleep disruption, and if such effects are mediated through SWS enhancement requires confirmation through prospective studies.
Pages 923-930
Commentary
J. Wesson Ashford
Treatment of Alzheimer’s Disease: Trazodone, Sleep, Serotonin, Norepinephrine, and Future Directions
Abstract: In this issue, an article by La et al. provides evidence that trazodone delayed cognitive decline in 25 participants with Alzheimer’s disease (AD), mild cognitive impairment, or normal cognition. For participants considered to have AD pathology, trazodone non-users declined at a rate 2.4 times greater than those taking trazodone for sleep over a 4-year period. In the analysis of sleep complaints, the relationship between trazodone, a widely used medication for sleep problems in the elderly, and cognition was associated with subjective improvement of sleep disruption. Due to the design of the study, it was not possible to prove that the benefit of slowing cognitive decline was due specifically to the improvement in sleep. However, trazodone uniquely improves the deeper phases of slow-wave sleep. Other sedative medications are generally associated with worse cognitive function over time, and they do not improve sleep characteristics as does trazodone. Trazodone has a variety of effects on several monoaminergic mechanisms: a potent serotonin 5-HT2A and α1-adrenergic receptor antagonist, a weak serotonin reuptake inhibitor, and a weak antihistamine or histamine H1 receptor inverse agonist. Because of the potential importance of this finding, further discussion is provided on the roles that trazodone may play in the modulation of monoamines, cognition, and the development of AD. If trazodone really does provide such a dramatic slowing in the development of dementia associated with AD, a great deal more research on trazodone is needed, including environmental and behavioral factors related to improvement of sleep, energy management, and neuroplasticity.
Pages 931-947
Fred Hudd*, Anna Shiel*, Matthew Harris, Paul Bowdler, Bryony Wood, Demitra Tsivos, Alfie Wearn, Michael Knight, Risto Kauppinen, Elizabeth Coulthard, Paul White, Myra Elizabeth Conway (Handling Associate Editor: Benedict Albensi) *These authors contributed equally to this work.
Novel Blood Biomarkers that Correlate with Cognitive Performance and Hippocampal Volumetry: Potential for Early Diagnosis of Alzheimer’s Disease
Abstract: Background: Differential diagnosis of people presenting with mild cognitive impairment (MCI) that will progress to Alzheimer’s disease (AD) remains clinically challenging. Current criteria used to define AD include a series of neuropsychological assessments together with relevant imaging analysis such as magnetic resonance imaging (MRI). The clinical sensitivity and specificity of these assessments would be improved by the concomitant use of novel serum biomarkers. The branched chain aminotransferase proteins (BCAT) are potential candidates as they are significantly elevated in AD brain, correlate with Braak Stage, and may have a role in AD pathology. Objective: In this hypothesis-driven project, we aimed to establish if serum BCAT and its metabolites are significantly altered in AD participants and assess their role as markers of disease pathology. Methods: Serum amino acids were measured using a triple quadrupole mass spectrometer for tandem mass spectroscopy together with BCAT levels using western blot analysis, coupled with neuropsychological assessments and MRI. Results: We present data supporting a substantive mutually correlated system between BCAT and glutamate, neuropsychological tests, and MRI for the diagnosis of AD. These three domains, individually, and in combination, show good utility in discriminating between groups. Our model indicates that BCAT and glutamate accurately distinguish between control and AD participants and in combination with the neuropsychological assessment, MoCA, improved the overall sensitivity to 1.00 and specificity to 0.978. Conclusion: These finding indicate that BCAT and glutamate have potential to improve the clinical utility and predictive power of existing methods of AD assessment and hold promise as early indicators of disease pathology.
Pages 949-960
Rachel U. Kristensen, Ane Nørgaard, Christina Jensen-Dahm, Christiane Gasse, Theresa Wimberley, Gunhild Waldemar
Changes in the Prevalence of Polypharmacy in People with and without Dementia from 2000 to 2014: A Nationwide Study
Abstract: Background: Polypharmacy, the use of multiple medications, has become increasingly widespread. Information on time trends in polypharmacy in people with dementia is limited, although they may be more susceptible to risks associated with polypharmacy. Objective: To examine changes in the prevalence of polypharmacy and excessive polypharmacy in people with dementia compared to changes in people without dementia. Methods: Repeated cross-sectional study of the entire Danish population aged ≥65 from 2000 (n=790,717) to 2014 (n=1,028,377) using linked register data on diagnoses, filled prescriptions, and demographic data. Multivariate analyses were performed to explore changes in the prevalence of polypharmacy and excessive polypharmacy (≥5 and ≥10 different prescription drugs). This was done before and after 2011 to examine whether increasing awareness of potential problems associated with polypharmacy has altered the trend. Estimates for people with and without dementia were compared. Results: In people with dementia, the prevalence of polypharmacy increased from 47.3% to 69.4% from 2000 to 2011 and excessive polypharmacy from 7.4% to 20.9%. In people without dementia, polypharmacy increased from 22.7% to 36.1% and excessive polypharmacy from 3.5% to 7.7%. The increase was significantly more marked in people with dementia across all age groups. From 2011 to 2014, the prevalence of polypharmacy and excessive polypharmacy remained relatively stable: Polypharmacy decreased negligibly from 69.4% to 68.1% in people with dementia and from 36.1% to 35.2% in people without dementia. Conclusion: Although the increasing trend has halted, polypharmacy remains widespread in people with dementia. Further research is needed to explore possible implications.
Pages 961-969
Qing Wang, Wenjun Zhou, Jie Zhang, for Alzheimer’s Disease Neuroimaging Initiative
Higher Apolipoprotein C-III Levels in Cerebrospinal Fluid Are Associated with Slower Cognitive Decline in Mild Cognitive Impairment
Abstract: Background: Although a growing body of evidence shows an important role of apolipoproteins in the pathogenesis of Alzheimer’s disease (AD), the association of apolipoprotein C-III (APOC-III) with cognitive decline is not clear. Objective: To examine whether higher cerebrospinal fluid (CSF) and plasma APOC-III levels were associated with better cognitive performance over time in the early stage of AD. Methods: Baseline CSF and plasma APOC-III levels were analyzed in relation to cross-sectionally and longitudinally cognitive performance over a 12-year period. Data were extracted from the Alzheimer’s Disease Neuroimaging Initiative database, and 234 subjects (89 subjects with normal cognition (NC) and 145 subjects with mild cognitive impairment (MCI)) with CSF APOC-III measurements and 454 subjects (58 subjects with NC and 396 subjects with MCI) with plasma APOC-III measurements were included. Results: In the cross-sectional study, we did not find a significant relationship between CSF APOC-III and cognitive performance in pooled individuals with MCI and NC. However, longitudinal analysis found that higher baseline CSF APOC-III was significantly associated with slower cognitive decline over a 12-year period in individuals with MCI, but not the healthy controls, after controlling for several covariates and Alzheimer biomarkers. Plasma APOC-III levels showed a mild correlation with CSF APOC-III levels, but were not associated with longitudinal cognitive changes in the pooled sample or in diagnosis-stratified analyses. Conclusions: Higher CSF APOC-III levels are significantly associated with slower cognitive decline over a 12-year period among individuals with MCI.
Pages 971-984
Patrícia Klobušiaková, Radek Mareček, Jan Fousek, Eva Výtvarová, Irena Rektorová (Handling Associate Editor: Zuzana Walker)
Connectivity Between Brain Networks Dynamically Reflects Cognitive Status of Parkinson’s Disease: A Longitudinal Study
Abstract: Background: Cognitive impairment in Parkinson’s disease (PD) is associated with altered connectivity of the resting state networks (RSNs). Longitudinal studies in well cognitively characterized PD subgroups are missing. Objectives: To assess changes of the whole-brain connectivity and between-network connectivity (BNC) of large-scale functional networks related to cognition in well characterized PD patients using a longitudinal study design and various analytical methods. Methods: We explored the whole-brain connectivity and BNC of the frontoparietal control network (FPCN) and the default mode, dorsal attention, and visual networks in PD with normal cognition (PD-NC, n=17) and mild cognitive impairment (PD-MCI, n=22) as compared to 51 healthy controls (HC). We applied regions of interest-based, partial least squares, and graph theory based network analyses. The differences among groups were analyzed at baseline and at the one-year follow-up visit (37 HC, 23 PD all). Results: The BNC of the FPCN and other RSNs was reduced, and the whole-brain analysis revealed increased characteristic path length and decreased average node strength, clustering coefficient, and global efficiency in PD-NC compared to HC. Values of all measures in PD-MCI were between that of HC and PD-NC. After one year, the BNC was further increased in the PD-all group; no changes were detected in HC. No cognitive domain z-scores deteriorated in either group. Conclusion: As compared to HC, PD-NC patients display a less efficient transfer of information globally and reduced BNC of the visual and frontoparietal control network. The BNC increases with time and MCI status, reflecting compensatory efforts.
Pages 985-993
Maurizio Gallucci, Carola Dell’Acqua, Cristina Bergamelli, Chiara Fenoglio, Maria Serpente, Daniela Galimberti, Vittorio Fiore, Stefano Medea, Michele Gregianin, Maria Elena Di Battista (Handling Associate Editor: Beatrice Arosio)
A Case with Early Onset Alzheimer’s Disease, Frontotemporal Hypometabolism, ApoE Genotype ε4/ε4 and C9ORF72 Intermediate Expansion: A Treviso Dementia (TREDEM) Registry Case Report
Abstract: We report the case of a woman firstly referred to our Memory Clinic at the age of 61, following the development of cognitive complaints and difficulties in sustained attention. The investigation that was performed showed: predominant executive dysfunctions at the neuropsychological evaluation, with mild, partial and stable involvement of the memory domain; cortical and subcortical atrophy with well-preserved hippocampal structures at MRI; marked fronto-temporal and moderate parietal hypometabolism from 18F-FDG PET study with a sparing of the posterior cingulate and precuneus; positivity of amyloid-β at 18F-Flutemetamol PET; an hexanucleotide intermediate repeats expansion of C9ORF72 gene (12//38 repeats) and ApoE genotype ε4/ε4. The patient was diagnosed with probable early onset frontal variant of Alzheimer’s disease (AD), presenting with a major executive function impairment. The lack of specific areas of brain atrophy, as well as the failure to meet the clinical criteria for any frontotemporal dementia, drove us to perform the aforementioned investigations, which yielded our final diagnosis. The present case highlights the need to take into consideration a diagnosis of frontal variant of AD when the metabolic and the clinical picture are somehow dissonant.
Pages 995-1005
Sinéad Moylett, Annabel Price, Rudolf N. Cardinal, Dag Aarsland, Christoph Mueller, Rob Stewart, John T. O’Brien
Clinical Presentation, Diagnostic Features, and Mortality in Dementia with Lewy Bodies
Abstract: Background: Dementia with Lewy bodies (DLB) is the second most common degenerative dementia in older people. However, rates of misdiagnosis are high, and little is known of its natural history and outcomes. Very few previous studies have been able to access routine clinical information for large, unbiased DLB cohorts in order to establish initial presentation, neuropsychological profile, and mortality. Objective: To examine in detail, symptom patterns at presentation and their association with outcomes, including mortality, in a large naturalistic DLB cohort from a secondary care sample. Methods: A retrospective cohort design was used to identify a DLB cohort (n = 251) from Cambridge and Peterborough NHS Foundation Trust (CPFT). Information relating to first consultation, diagnosis, and DLB diagnostic features were extracted. Results: A wide range of presenting complaints and differential initial diagnoses were identified for the cohort. Along with memory loss (27.1%) and hallucinations (25.4%), low mood (25.1%) was noted as a key presenting complaint among the DLB cohort. Rates of REM sleep disorder were considerably lower (8.4%) than would be expected. Deficits in non-amnestic cognitive domains were associated with reduced mortality compared with amnestic-only presentations. Conclusion: Individuals later diagnosed with DLB present initially to secondary care with a wide range of symptoms and complaints, some of which are not immediately suggestive of a DLB diagnosis. More examinations of large cohorts such as this are needed to further elucidate the complex presentation and clinical course of DLB, and to confirm whether amnestic-only presentation confers a worse outcome.
Pages 1007-1019
Yanfei Ding, Xiaoming Bao, Lifeng Lao, Yunxiang Ling, Qinwen Wang, Shujun Xu (Handling Associate Editor: Ling-Qiang Zhu)
p-Hydroxybenzyl Alcohol Prevents Memory Deficits by Increasing Neurotrophic Factors and Decreasing Inflammatory Factors in a Mice Model of Alzheimer’s Disease
Abstract: p-hydroxybenzyl alcohol (HBA) is one of the major components of Gastrodia elata Blume (GEB) phenolic compound. HBA has been reported to have a protective effect on amyloid-β (Aβ) induced cell death. However, the systemic effects and the detail molecular mechanism of HBA in Alzheimer’s disease (AD) animal models is not clear. In this study, we revealed the protective effects and the potential mechanisms of HBA on the impairments of cognitive function induced by soluble Aβ oligomers. Our results showed that HBA prevented neuronal cells death in a dose-dependent manner. The working memory and the spatial memory were significantly lower in AD model mice. HBA treatment prevented the memory deficits of the AD mice. HBA treatment significantly prevented the decreased spine density and decreased expression levels of synaptic proteins induced by Aβ42. In addition, both mRNA levels and protein levels of brain-derived neurotrophic factor (BDNF) and glial cell line-derived neurotrophic factor (GDNF) in the Aβ42-treated mice were decreased, the decreases were prevented by HBA treatment. The expression levels of TNF-α and IL-1β were increased by Aβ42 treatment and the increase can be prevented by the HBA treatment. Moreover, HBA prevents the decreases in the level of nuclear erythroid 2 p45-related factor 2 (Nrf2) induced by Aβ42 in hippocampal. Thus, we predict that HBA might prevent Aβ42 oligomer-induced synapse and cognitive impairments through multiple targets including increasing Nrf2, increasing neurotrophic factors and decreasing inflammatory factors. Our study provided novel insights into the cellular mechanisms for the protective effects of HBA on AD.
Pages 1021-1034
Yan Ji*, Xiaowan Wang*, Colin Kalicki, Blaise W. Menta, Megan Baumgardner, Scott J. Koppel, Ian W. Weidling, Judit Perez-Ortiz, Heather M. Wilkins, Russell H. Swerdlow *These authors contributed equally to this work.
Effects of Microglial Cytokines on Alzheimer’s Disease-Related Phenomena
Abstract: Recent association studies indicate several genes highly expressed by microglia influence Alzheimer’s disease (AD) risk, which suggests microglial function contributes to this disease. Here, we evaluated how one component of microglial function, cytokine release, affects AD-related phenomena. First, we used a 3-hour lipopolysaccharide (LPS) treatment to activate mouse BV2 microglial cells. Next, we removed the LPS-containing medium, added LPS-free medium, and after 6 hours collected the medium conditioned by the activated BV2 microglial cells. We then exposed human neuronal SH-SY5Y cells to the conditioned medium for 24 hours. At the end of the 24-hour exposure, we assessed amyloid-β protein precursor (AβPP), tau, apolipoprotein E (ApoE), and lipid status. The amount of AβPP was unaffected, although a slight decrease in soluble AβPPα suggested a subtle reduction in AβPP non-amyloidogenic processing occurred. Tau mRNA increased, but total and phosphorylated tau levels were unchanged. ApoE mRNA increased, while ApoE protein levels were lower. Per cell lipid droplet number decreased and lipid oxidation increased. These results show cytokine release by activated microglial cells can influence specific AD-relevant physiologies and pathologies.
Pages 1035-1043
Carolyn A. Unsworth, Kay Russell, Robin Lovell, Michael Woodward, Matthew Browne (Handling Associate Editor: Catherine Roe)
Effect of Navigation Problems, Assessment Location, and a Practice Test on Driving Assessment Performance for People with Alzheimer’s Disease
Abstract: Background: People with Alzheimer’s disease may be required to undertake clinical and on-road assessments to determine fitness to drive. The manner in which on-road assessments are conducted with drivers who do and do not have navigational problems may affect the outcome. Objectives: Investigate the effect of 1) navigational difficulties, 2) location of assessment (un/familiar area) and assessment order, and 3) undertaking a second assessment (practice), on passing an on-road driving assessment. Methods: Forty-three drivers undertook an Occupational Therapy-Driver Assessment Off Road Assessment (OT-DORA) Battery which included the Drive Home Maze Test (DHMT). Participants with/without a history of navigational problems were randomly allocated into three groups: 1) Unfamiliar/then familiar area assessment; 2) Unfamiliar/unfamiliar; 3) familiar/unfamiliar. An on-road assessment protocol was used including over 100 expected behaviors at nominated points along the directed route. For familiar area assessments, the driver self-navigated from their home to shops and services. A pass/fail decision was made for each assessment. Results: A generalized linear mixed effects model showed neither location, nor practice affected passing the on-road assessment. Participants with navigational problems were six times less likely to pass regardless of route familiarity and direction method, and the DHMT was a significant negative predictor of passing. Conclusion: Drivers with Alzheimer’s disease who have navigational problems and are slow to complete the DHMT are unlikely to pass an on-road assessment. However, navigation and maze completion skills may be a proxy for an underlying cognitive skill underpinning driving performance.
Pages 1045-1054
Marjanne D. van der Hoek, Arie Nieuwenhuizen, Jaap Keijer, J. Wesson Ashford
The MemTrax Test Compared to the Montreal Cognitive Assessment Estimation of Mild Cognitive Impairment
Abstract: Cognitive impairment is a leading cause of dysfunction in the elderly. When mild cognitive impairment (MCI) occurs in elderly, it is frequently a prodromal condition to dementia. The Montreal Cognitive Assessment (MoCA) is a commonly used tool to screen for MCI. However, this test requires a face-to-face administration and is composed of an assortment of questions whose responses are added together by the rater to provide a score whose precise meaning has been controversial. This study was designed to evaluate the performance of a computerized memory test (MemTrax), which is an adaptation of a continuous recognition task, with respect to the MoCA. Two outcome measures are generated from the MemTrax test: MemTraxspeed and MemTraxcorrect. Subjects were administered the MoCA and the MemTrax test. Based on the results of the MoCA, subjects were divided in two groups of cognitive status: normal cognition (n = 45) and MCI (n = 37). Mean MemTrax scores were significantly lower in the MCI than in the normal cognition group. All MemTrax outcome variables were positively associated with the MoCA. Two methods, computing the average MTX score and linear regression were used to estimate the cutoff values of the MemTrax test to detect MCI. These methods showed that for the outcome MemTraxspeed a score below the range of 0.87 – 91 s-1 is an indication of MCI, and for the outcome MemTraxcorrect a score below the range of 85 – 90% is an indication for MCI.
Pages 1055-1065
Tobias Möllers, Laura Perna, Peter Ihle, Ingrid Schubert, Jürgen Bauer, Hermann Brenner (Handling Associate Editor: Christopher Black)
Factors Associated with Length of Stay in Hospital Patients with and without Dementia
Abstract: Background: Hospital care of older adults, especially of those with dementia, is associated with a high risk of complications and increased mortality. Adverse events are often triggered by hospital-related factors, hence the time spent in hospitals should be limited. There is little knowledge of the specific factors influencing hospitalizations of older persons. Objectives: To assess the duration of length of stay (LOS) and risk factors of increased LOS, and, specifically, the role of delirium and neuropsychiatric symptoms (NPS) among a large sample of older adults with and without dementia in Germany. Methods: A claims data based dynamic retrospective cohort study from 2004 to 2015 was conducted. People with dementia (PWD) were identified using ICD-10 codes and the application of diagnostic measures. A control group without diagnosis of dementia (CG) were matched in a 3:1 ratio. Multivariate methods were used to investigate the factors associated with LOS. Results: 7,139 PWD and 21,417 controls were included. PWD had longer hospitalizations (first LOS: +4.3 days; second LOS: +0.2 days) than the CG. Diagnosis of delirium was associated with LOS, both for PWD (first LOS: +9.6 days; second LOS: +5.3 days) and CG (first LOS: +13.7 days; second LOS: +7.2 days). Conclusion: Major determinants of LOS were similar in PWD and the CG. The strongest association was found for the presence of delirium and NPS. Future research should focus on prevention and intervention strategies that may reduce the impact of delirium as well as NPS on the length of stay especially for PWD.
Pages 1067-1077
Jing-Huan Deng, Kai-Yong Huang, Xiao-Xiao Hu, Xiao-Wei Huang, Xian-Yan Tang, Xiao Wei, Lei Feng*, Guo-Dong Lu* (Handling Associate Editor: Jin-Tai Yu) *These authors contributed equally to the work.
Midlife Long-Hour Working and Later-life Social Engagement Are Associated with Reduced Risks of Mild Cognitive Impairment among Community-Living Singapore Elderly
Abstract: Mild cognitive impairment (MCI), as a transitional stage between normal aging and dementia, causes cognitive decline among one-fifth of elders aged 65 years and older. Health-related lifestyles (HRL) are generally regarded as modifiable influencing factors of cognitive decline. The present study investigated how HRLs at two different life stages (one at midlife and the other at later life) affect MCI occurrence among community-dwelling elders, as part of the Diet and Healthy Aging (DaHA) study in Singapore. The frequencies of major HRL activities were compared between 119 clinical diagnosed MCI cases and 632 normal ageing controls with functional cognition. The associations of HRLs with MCI were determined by multivariate logistic regression analysis and adjusted according to known factors including age, childhood education, and major chronic diseases (hypertension, stroke, diabetes, and cataracts or glaucoma). Long-hour working in midlife (adjusted OR=0.418 with 95%CI 0.215-0.812) and social engagement in later-life (adjusted OR=0.532 with 95%CI 0.329-0.859) were associated with reduced risks of MCI, respectively. It is important to note that those elders who had both midlife long-hour working and later-life social engagement were related to the lowest risk of MCI (adjusted OR=0.285 with 95%CI 0.143-0.565), when compared to the least active subgroup who neither had worked long hours in midlife nor participate in social activities in later-life. Therefore, the present study demonstrated that midlife long-hour working and later-life social engagement were modifiable factors for the maintenance of cognitive functions.
Pages 1079-1087
Tatsuo Manabe*, Akihiro Matsumura*, Kazuki Yokokawa, Taro Saito, Mai Fujikuraa, Naotoshi Iwahara, Takashi Matsushita, Syuuichirou Suzuki, Shin Hisahara, Jun Kawamata, Hiromi Suzuki, Miho C. Emoto, Hirotada G. Fujii, Shun Shimohama *These authors contributed equally to this work.
Evaluation of Mitochondrial Oxidative Stress in the Brain of a Transgenic Mouse Model of Alzheimer’s Disease by in vitro Electron Paramagnetic Resonance Spectroscopy
Abstract: Alzheimer’s disease (AD) is one of the most common neurodegenerative diseases responsible for progressive dementia. Deposition of amyloid-β (Aβ) in the brain is the most important pathophysiological hallmark of AD. In addition, recent evidence indicates that reactive oxygen species (ROS) derived from mitochondria contribute to progression of AD pathology. We thus hypothesized that Aβ accumulates and oxidative stress increases in the brain mitochondria of a transgenic mouse model of AD (APdE9). We measured the quantity of Aβ and the activity of the antioxidant enzyme superoxide dismutase (SOD) in brain mitochondrial fractions prepared from APdE9 and wild-type (WT) mice aged 6, 9, 15, and 18 months. We also quantified the age-related changes in redox status in the mitochondrial fractions obtained from both APdE9 and WT mouse brains by electron paramagnetic resonance (EPR) spectrometry using a paramagnetic nitroxide “Mito-Tempo” [(2-(2,2,6,6-Tetramethylpiperidin-1-oxyl-4-ylamino)-2-oxoethyl) triphenylphosphonium chloride monohydrate] as a mitochondria-targeted redox-sensitive probe. In APdE9 mice, Aβ accumulated in brain mitochondria earlier than in the non-mitochondrial fraction of the brain. Furthermore, increased oxidative stress was demonstrated in brain mitochondria of APdE9 mice by in vitro SOD assay as well as EPR spectroscopy. EPR combined with a mitochondria-targeted redox-sensitive nitroxide probe is a potentially powerful tool to elucidate the etiology of AD and facilitate the development of new therapeutic strategies for AD.
Pages 1089-1106
Ci-Di Chen, Ella Zeldich, Christina Khodr, Kaddy Camara, Tze Yu Tung, Emma C. Lauder, Patrick Mullen, Taryn J. Polanco, Yen-Yu Liu, Dean Zeldich, Weiming Xia, William E. Van Nostrand, Lauren E. Brown, John A. Porco, Jr., Carmela R. Abraham (Handling Associate Editor: Ashley Bush)
Small Molecule Amyloid-β Protein Precursor Processing Modulators Lower Amyloid-β Peptide Levels via cKit Signaling
Abstract: Alzheimer’s disease (AD) is characterized by the accumulation of neurotoxic amyloid-β (Aβ) peptides consisting of 39-43 amino acids, proteolytically derived fragments of the amyloid-β protein precursor (AβPP), and the accumulation of the hyperphosphorylated microtubule-associated protein tau. Inhibiting Aβ production may reduce neurodegeneration and cognitive dysfunction associated with AD. We have previously used an AβPP-firefly luciferase enzyme complementation assay to conduct a high throughput screen of a compound library for inhibitors of AβPP dimerization, and identified a compound that reduces Aβ levels. In the present study, we have identified an analog, compound Y10, which also reduced Aβ. Initial kinase profiling assays identified the receptor tyrosine kinase cKit as a putative Y10 target. To elucidate the precise mechanism involved, AβPP phosphorylation was examined by IP-western blotting. We found that Y10 inhibits cKit phosphorylation and increases AβPP phosphorylation mainly on tyrosine residue Y743, according to AβP751 numbering. A known cKit inhibitor and siRNA specific to cKit were also found to increase AβPP phosphorylation and lower Aβ levels. We also investigated a cKit downstream signaling molecule, the Shp2 phosphatase, and found that known Shp2 inhibitors and siRNA specific to Shp2 also increase AβPP phosphorylation, suggesting that the cKit signaling pathway is also involved in AβPP phosphorylation and Aβ production. We further found that inhibitors of both cKit and Shp2 enhance AβPP surface localization. Thus, regulation of AβPP phosphorylation by small molecules should be considered as a novel therapeutic intervention for AD.
