David R. Elmaleh, Martin R. Farlow, Peter S. Conti, Ronald G. Tompkins, Ljiljana Kundakovic, Rudolph E. Tanzi (Handling Associate Editor: Carmela Abraham)
Developing Effective Alzheimer’s Disease Therapies: Clinical Experience and Future Directions
Abstract: Alzheimer’s disease (AD) clinical trials, focused on disease modifying drugs and conducted in patients with mild to moderate AD, as well as prodromal (early) AD, have failed to reach efficacy endpoints in improving cognitive function in most cases to date or have been terminated due to adverse events. Drugs that have reached clinical stage were reviewed using web resources (such as clinicaltrials.gov, alzforum.org, company press releases, and peer reviewed literature) to identify late stage (Phase II and Phase III) efficacy clinical trials and summarize reasons for their failure. For each drug, only the latest clinical trials and ongoing trials that aimed at improving cognitive function were included in the analysis. Here we highlight the potential reasons that have hindered clinical success, including clinical trial design and choice of outcome measures, heterogeneity of patient populations, difficulties in diagnosing and staging the disease, drug design, mechanism of action, and toxicity related to the long-term use. We review and suggest approaches for AD clinical trial design aimed at improving our ability to identify novel therapies for this devastating disease.
Anna Oudin, John Andersson, Anna Sundström, Annelie Nordin Adolfssond Daniel Oudin Åström, Rolf Adolfsson, Bertil Forsberg, Maria Nordin
Traffic-Related Air Pollution as a Risk Factor for Dementia: No Clear Modifying Effects of APOE ε4 in the Betula Cohort
Abstract: It is widely known that the apolipoprotein E (APOE) ɛ4 allele imposes a higher risk for Alzheimer’s disease (AD). Recent evidence suggests that exposure to air pollution is also a risk factor for AD, and results from a few studies indicate that the effect of air pollution on cognitive function and dementia is stronger in APOE ɛ4 carriers than in non-carriers. Air pollution and interaction with APOE ɛ4 on AD risk thus merits further attention. We studied dementia incidence over a 15-year period from the longitudinal Betula study in Northern Sweden. As a marker for long-term exposure to traffic-related air pollution, we used modelled annual mean nitrogen oxide levels at the residential address of the participants at start of follow-up. Nitrogen oxide correlate well with fine particulate air pollution levels in the study area. We had full data on air pollution, incidence of AD and vascular dementia (VaD), APOE ɛ4 carrier status, and relevant confounding factors for 1,567 participants. As expected, air pollution was rather clearly associated with dementia incidence. However, there was no evidence for a modifying effect by APOE ε4 on the association (p-value for interaction >0.30 for both total dementia (AD+VaD) and AD). The results from this study do not imply that adverse effects of air pollution on dementia incidence is limited to, or stronger in, APOE ε4 carriers than in the total population.
Stephanie Folley, Ang Zhou, David J. Llewellyn, Elina Hyppönen
Physical Activity, APOE Genotype, and Cognitive Decline: Exploring Gene-Environment Interactions in the UK Biobank
Abstract: Background: Apolipoprotein E (APOE) genotype affects the risk of Alzheimer’s disease (AD) with inconclusive evidence on the opportunity to mitigate related adverse effects by lifestyle changes. Objective: To examine the individual and interactive associations of APOE and objectively-measured physical activity (PA) and sedentary activity with cognitive decline. Methods: We used data from middle-aged and older UK Biobank participants with repeat tests on visuospatial memory (n = 52,767) and fluid intelligence (n = 19,713), and who also took part in the accelerometer sub-study. PA and sedentary activity were assessed by a wrist-worn accelerometer over a seven-day period. Cognitive decline was defined as >1 standard deviation (SD) reduction in memory or fluid intelligence score, and the mean follow up from baseline was 5.8 years. Results: There was an age dependent association between APOE ε4 genotype and memory decline (page-interaction = 0.01), with the association only seen in participants who were >65 years (OR 1.33, 95%CI 1.11 to 1.24; for 0.63 for all). Conclusion: This large-scale study using objectively measured PA did not find differential effects of PA on cognitive decline based on APOE genotype.
Perrine André, Cécilia Samieri, Charline Buisson, Jean-François Dartigues, Catherine Helmer, Fabienne Laugerette, Catherine Féart
Lipopolysaccharide-Binding Protein, Soluble CD14, and the Long-Term Risk of Alzheimer’s Disease: A Nested Case-Control Pilot Study of Older Community Dwellers from the Three-City Cohort
Abstract: Background: Identifying the mechanisms involved in the pathogenesis of Alzheimer’s disease (AD) remains crucially important. Chronic age-related low-grade inflammation is considered to be one such mechanism, although its causes are unclear. Lipopolysaccharide (LPS)-type endotoxins, a major component of the outer membrane of Gram-negative bacteria, are known as potent pro-inflammatory molecules. Therefore, we hypothesized that greater exposure to circulating LPS, potentially mediated by the inflammatory pathway, would be a key step of the onset of AD. Objective: The aim of this study was to investigate the link between plasma endotoxin-exposure, inflammation, and AD. Methods: Applying a nested case-control design, we evaluated the associations among baseline plasma endotoxin-exposure (assessed by measuring LPS-binding protein (LBP) and soluble cluster of differentiation-14 (sCD14) levels), inflammation (assessed by measuring interleukin-6 (IL6) levels), and the odds of developing AD over 12 years. Selected from a population-based cohort, 212 incident cases of AD were matched with 424 controls without dementia with regard to age, gender, and education level. Results: After adjusting for a large set of confounders, including the use of anti-inflammatory drugs, only higher LBP levels were significantly associated with a 30% higher odds ratio of developing AD over 12 years (OR 1.30, 95%CIs [1.07 - 1.59]), regardless of IL6 levels. Conclusion: This large case-control study provides preliminary results concerning plasma endotoxin-exposure among the elderly and suggests that higher LBP levels, an acute-phase reactant involved in the pro-inflammatory response to LPS, are associated with higher odds of developing AD.
Christopher Karayiannis, Chris Moran, James E. Sharman, Richard Beare, Stephen J. Quinn, Thanh G. Phan, Amanda G. Wood, Amanda G. Thrift, Wei C. Wang, Velandai Srikanth
Blood Pressure, Aortic Stiffness, Hemodynamics, and Cognition in Twin Pairs Discordant for Type 2 Diabetes
Abstract: Background: Type 2 diabetes (T2D) is associated with an increased risk of cognitive impairment and dementia with poorly understood underlying mechanisms. Objective: We examined the role of blood pressure (BP), aortic stiffness, and hemodynamics in this association. Methods: Cross-sectional sample of late middle-aged twins discordant for T2D from the Australian Twin Registry. Measurements included neuropsychological battery and brain MRI including arterial spin labelling (ASL) to measure cerebral perfusion. Mobil-o-Graph devices were used to non-invasively obtain 24-hour BP, aortic stiffness, and hemodynamic measures. Using mixed modelling, we studied associations of T2D with cognition, MRI measures, BP, aortic stiffness, and hemodynamics. Results: There were 23 twin pairs with mean age 63.7 (SD=6.1) years. T2D (β=-0.45, p<0.001) and age (β=-0.05, p=0.022) were independently associated with poorer attention but not with memory or perceptual speed. T2D was associated with reduced nocturnal central systolic BP dipping (β=-3.79, p=0.027), but not with BP, aortic stiffness, cerebral perfusion, or other hemodynamic measures. There was a statistically significant interaction between T2D and central systolic BP dipping in predicting attention scores (both p<0.05 for the interaction term) whereby there was a positive association between BP dipping and attention scores in those with T2D, but not in those without T2D. Conclusion: We found an association between T2D and reduced nocturnal central systolic dipping, but not with any other measures of BP, stiffness or hemodynamic measures. Further study of the role of nocturnal central BP dipping in the association between T2D and cognitive impairment may help identify potential mechanisms.
Pratishtha Chatterjee, Mitra Elmi, Kathryn Goozee, Tejal Shah, Hamid R. Sohrabi, Cintia B. Dias, Steve Pedrini, Kaikai Shen, Prita R. Asih, Preeti Dave, Kevin Taddei, Hugo Vanderstichele, Henrik Zetterberg, Kaj Blennow, Ralph N. Martins
Ultrasensitive Detection of Plasma Amyloid-β as a Biomarker for Cognitively Normal Elderly Individuals at Risk of Alzheimer’s Disease
Abstract: Background: Aberrant amyloid-β (Aβ) deposition in the brain occurs two decades prior to the manifestation of Alzheimer’s disease (AD) clinical symptoms and therefore brain Aβ load measured using PET serves as a gold standard biomarker for the early diagnosis of AD. However, the uneconomical nature of PET makes blood markers, that reflect brain Aβ deposition, attractive candidates for investigation as surrogate markers. Objective: Investigation of plasma Aβ as a surrogate marker for brain Aβ deposition in cognitively normal elderly individuals. Methods: Plasma Aβ40 and Aβ42 concentrations were measured using the ultrasensitive Single Molecule Array (Simoa) assay in 95 cognitively normal elderly individuals, who have all undergone PET to assess brain Aβ deposition. Based on the standard uptake value ratios (SUVR) obtained from PET imaging, using the tracer 18F-Florbetaben, plasma Aβ was compared between 32 participants assessed to have low brain Aβ load (Aβ-, SUVR<1.35) and 63 assessed to have high brain Aβ load (Aβ+, SUVR≥1.35). Results: Plasma Aβ42/Aβ40 ratios were lower in the Aβ+ group compared to the Aβ- group. Plasma Aβ40 and Aβ42 levels were not significantly different between Aβ- and Aβ+ groups, although a trend of higher plasma Aβ40 was observed in the Aβ+ group. Additionally, plasma Aβ42/Aβ40 ratios along with the known AD risk factors, age and APOE ε4 status, resulted in Aβ+ participants being distinguished from Aβ- participants based on an area under the receiver operating characteristic curve shown to be 78%. Conclusion: Plasma Aβ ratios in this study are a potential biomarker for brain Aβ deposition and therefore, for preclinical AD. However, this method to measure plasma Aβ needs further development to increase the accuracy of this promising AD blood biomarker.
Laura Vaskivuo, Laura Hokkanen, Tuomo Hänninen, Riitta Antikainen, Lars Bäckman, Tiina Laatikainen, Teemu Paajanen, Anna Stigsdotter-Neely, Timo Strandberg, Jaakko Tuomilehto, Hilkka Soininen, Miia Kivipelto, Tiia Ngandu (Handling Associate Editor: Sylvie Belleville)
Self and Informant Memory Reports in FINGER: Associations with Two-Year Cognitive Change
Abstract: Background: Subjective memory complaints (SMCs) may be the first sign of cognitive decline in aging. Objective: To examine whether SMCs reported by oneself and informant predict cognitive change over 2 years among at-risk elderly people, and to determine the relationship of different types of SMCs (prospective and retrospective memory complaints) and change in cognitive function. Methods: This investigation is part of the FINGER project, which is a multicenter randomized controlled trial aiming at preventing cognitive decline in cognitively healthy older adults with increased risk of dementia. A subsample of 303 control-group participants (aged 60-80 years) and their informants (n=261) rated the frequency of SMCs, using the Prospective and Retrospective Memory Questionnaire (PRMQ). Cognitive performance was measured at baseline and at 1- and 2-year follow-up visits using a neuropsychological test battery. Results: Participants who reported more SMCs improved less in global cognition, executive function, and memory during the subsequent 2 years in the fully-adjusted analyses. Self-reported retrospective memory problems predicted less improvement in all cognitive domains, whereas prospective memory problems did not. Informant-reported memory problems were not linked to subsequent change in cognition. Conclusion: Our results indicate that self-reported SMCs, measured with PRMQ, predict future cognitive change in several cognitive domains. By contrast, reports by informants were not linked to changes in cognition. Among cognitively healthy at-risk elderly individuals, the persons themselves observe more easily problems relevant for their future cognitive trajectories than their informants.
Thitiporn Supasitthumrong, Chavit Tunvirachaisakul, Daruj Aniwattanapong, Sookjaroen Tangwongchai, Phenphichcha Chuchuen, Itthipol Tawankanjanachot, Thiti Snabboon, Solaphat Hemrungrojn, Andre F. Carvalho, Michael Maes
Peripheral Blood Biomarkers Coupled with the Apolipoprotein E4 Genotype Are Strongly Associated with Semantic and Episodic Memory Impairments in Elderly Subjects with Amnestic Mild Cognitive Impairment and Alzheimer’s Disease
Abstract: Background: The Apolipoprotein E4 (ApoE4) genotype is strongly associated with Alzheimer’s disease (AD), although the presence of the ApoE4 allele alone is not sufficient to explain AD. The pathophysiology of amnestic mild cognitive impairment (aMCI) remains unclear. Objective: This study aims to examine associations between peripheral blood biomarkers coupled with ApoE4 and episodic and semantic memory. Methods: The CERAD battery was completed and various biomarkers were assayed in 60 subjects with aMCI, 60 with AD, and 62 healthy controls. Results: Deficits in semantic and episodic memory were significantly predicted by anion gap and bicarbonate, albumin, and glucose coupled with ApoE4. Furthermore, these peripheral biomarkers interacted with ApoE to predict greater memory impairments. Conclusions: Peripheral blood biomarkers may interact with pathways related to ApoE4 to predict greater semantic and episodic memory impairments, thus contributing to the pathophysiology of aMCI and AD. Our data suggest that the transition from aMCI to AD could at least in some cases be associated with significant interactions between ApoE4 and those peripheral blood biomarkers.
Anna Pedrinolla*, Stefano Tamburin*, Anna Brasioli, Alessio Sollima, Cristina Fonte, Ettore Muti, Nicola Smania, Federico Schena, Massimo Venturelli *These authors contributed equally to this work.
An Indoor Therapeutic Garden for Behavioral Symptoms in Alzheimer’s Disease: A Randomized Controlled Trial
Abstract: Background: Behavioral and psychological symptoms of dementia (BPSD) affect 60–90% of patients with Alzheimer’s disease (AD). Objective: To determine if environmental therapy is an effective strategy to reduce BPSD, we tested 163 patients with AD with Neuropsychiatric Inventory (NPI) before and after 6 months of an indoor therapeutic garden (TG) or standard environment. Methods: A single-blind randomized controlled trial on AD patients with BPSD. Participants were randomized to an indoor TG (N = 82), or standard environment (control, N = 81) for 6 months. Primary outcome: change in the NPI score from baseline (T0) to end of treatment (T1). Secondary outcomes: change in use of quetiapine, cognition, activities of daily living, salivary cortisol, blood pressure from T0 to T1. Results: NPI score significantly ameliorated (TG versus control: -31.8 points), quetiapine dosage (-150 mg), blood pressure (-2.6 mm Hg), and salivary cortisol (-6.4 to -2.1 Nmol/l) were significantly reduced, the Mini-Mental State Examination significantly improved (1.8 points) in the TG versus control arm at T1 (p < 0.001). No adverse events were reported. Conclusion: The indoor TG seems safe and may reduce BPSD, medication intake, and cortisol levels in AD.
Yuan Tian*, Mingrui Song* (Handling Associate Editor: Yong Guo) *These authors contributed equally to this work.
Sevoflurane Affects Memory Through Impairing Insulin-Like Growth Factor Receptor Signaling
Abstract: Administration of sevoflurane (SEVO) may induce learning and memory deficits, which increases the chances of developing Alzheimer’s disease. Here, we studied the effects of SEVO exposure on rats with a focus on the role of insulin-like growth factor (IGF) signaling. SEVO exposure significantly increased neuron cell apoptosis, and caused poor performance of the rats in behavior tests, by suppressing IGF-1 receptor (IGF1R). Bioinformatic analysis predicted microRNA(miR)-223-3p as an IGF1R-binding miRNA, the level of which increased in neurons after exposure to SEVO. In vitro, miR-223-3p suppressed the translation of IGF1R in neural cells. Moreover, transfection with antisense of miR-223-3p significantly attenuated SEVO exposure-induced neuron cell apoptosis. Taken together, these data suggest that SEVO-induced miR-223-3p upregulation suppresses IGF1R to impair IGF signaling, which subsequently leads to learning and memory impairments.
Moeko Noguchi-Shinohara, Kohei Hirako, Makoto Fujiu, Masahiko Sagae, Hikaru Samuta, Hiroyuki Nakamura, Masahito Yamada (Handling Associate Editor: Robert Friedland)
Presence of a Synergistic Interaction Between Current Cigarette Smoking and Diabetes Mellitus on Development of Dementia in Older Adults
Abstract: Background: Both cigarette smoking and diabetes mellitus are well-established risk factors for development of dementia. However, the interaction between smoking and diabetes is yet unknown. Objective: In this study, we clarify association between smoking, diabetes, and dementia risk in older adults. Methods: Participants in this study included community residents aged 65 years and older who had participated in a health checkup in 2006, followed for 10 years (n = 9,403) and had long-term care insurance information data. Furthermore, the risk estimates of smoking status and diabetes diagnosis on dementia adjusted for the competing risk of death prior to dementia were analyzed. Results: During follow-up, 2,647 participants developed dementia. The smoking status–diabetes interaction on development of dementia was statistically significant (p ≤ 0.001). Among those patients exposed to both factors, 17% of risk of development of dementia was attributable to the interaction of these factors. Current smokers with diabetes had significantly greater risks of development of dementia than never smokers without diabetes (reference): multivariable-adjusted risk of dementia in current smokers without diabetes (subdistribution hazard ratio [sHR], 1.25; 95% confidence interval [CI], 1.05–1.48); never smokers with diabetes (1.31, 1.16–1.47); and current smokers with diabetes (1.86, 1.39–2.48). However, no such association was noted for former smokers with and without diabetes. Conclusions: Current smoking, but not former smoking, was associated with increased risk of development of dementia in older adults with and without diabetes. Moreover, the synergistic effect of current smoking and diabetes on dementia was noted.
Amandine Mayelle, Mohamad El Haj, Pascal Antoine
Awareness of Self and Disease Assessment: Development and Validation of a Subjective Measure in People with Alzheimer’s Disease
Abstract: Background: People with Alzheimer’s disease (PwAD) remain able to speak coherently about their daily life for a long time, and their level of awareness could be determined through their discourse. In a grounded-theory approach, awareness of self and awareness of disease are intertwined and can be observed through three domains: mechanisms, objects and modes of expression. Objective: Based on preliminary results, in this article, we present the ASDA (Awareness of Self and Disease Assessment), a new subjective measurement tool for awareness in PwAD. To consider its use in research and practice, we initially performed validation analyses, including internal consistency, test-retest reliability and interrater reliability analyses. Methods: The new assessment tool consists of a semi-structured interview and ratings of 22 items divided into three categories. As part of our observational study, we assessed a sample of 28 PwAD who participated in four interviews (one every two weeks). Results: The ASDA shows good homogeneity within the domains of awareness and a certain degree of stability between two measurement times and between investigators. Missing values in the results provided information regarding awareness levels within and across the subjects. Conclusion: The results suggest that awareness could be assessed through subjective experience without reference to a comparison.
Keivan Javanshiri, Mattias Haglund, Elisabet Englund (Handling Associate Editor: Irina Alafuzoff)
Cardiovascular Disease, Diabetes Mellitus, and Hypertension in Lewy Body Disease: A Comparison with Other Dementia Disorders
Abstract: Background: Research concerning the potential roles of cardiovascular disease (CaVD) and diabetes mellitus (DM) as risk factors for Lewy body disease (LBD) is limited. These disorders are, however, established risk factors for vascular dementia (VaD) and have been proposed as risk factors for Alzheimer’s disease (AD). Objective: The aim of this study was to investigate the prevalence of CaVD and DM in LBD and compare the results with previous findings in cases with AD, VaD, and mixed AD-VaD (MD). Methods: Autopsy reports at the Clinical Department of Pathology in Lund from 2001–2018 were analyzed. All cases with a complete neuropathological diagnosis of LBD were selected, not distinguishing between subjects with clinical Parkinson disease dementia and dementia with Lewy bodies, on the condition of a clinical diagnosis of dementia. Clinical data were retrieved through the patients’ medical records and the Swedish National Diabetes Register (NDR) and compared with those of the AD, VaD, and MD cases. Results: In LBD, there was less CaVD, significantly less DM (p=0.002) and likewise significantly less hypertension (p <0.001) than in VaD. The results of the LBD group were consistent with the results of the AD group. Conclusion: Our findings of a low prevalence of CaVD and CaVD risk factors in LBD and in AD argue against the association between these risk factors and their contribution to the development of neurodegenerative diseases.
Petr Schlegel, Michal Novotny, Blanka Klimova, Martin Valis
“Muscle-Gut-Brain Axis”: Can Physical Activity Help Patients with Alzheimer’s Disease Due to Microbiome Modulation?
Abstract: Alzheimer’s disease (AD) is one of the most common forms of dementia, which cannot be cured at the moment. Therefore, researchers also look for the alternative approaches to its treatment. It is suggested that changes in human gut microbiome mediated by exercise could influence the development and progression of AD and a new term "muscle-gut-brain axis" is introduced. There is much evidence to support this assumption. The gut microbiology is closely related to a wide range of diseases of the nervous system and therefore any negative qualitative and quantitative changes in the composition of the gut microbiota can potentially contribute to the pathophysiology of AD. Research shows that the treatment of intestinal dysbiosis with probiotics/synbiotics/eubiotics can prevent or alleviate the symptoms of these chronic neurological diseases. Studies also point to the positive effects of movement on the health of seniors. A positive correlation can be found between cognitive functions and physical stress, both in the elderly and in AD patients. Even short-term interventions with a relatively low frequency seem to produce positive results, while physical activities can be performed by using relatively simple and cost-effective means. In addition, physical activity can significantly modulate gut microbiome. Thus, it can be concluded that physical activity in humans seems to correlate with gut microbiome, which can prevent the incidence and development of AD.
Jekaterina Krishtal, Kristel Metsla, Olga Bragina, Vello Tõugu, Peep Palumaa
Toxicity of Amyloid-β Peptides Varies Depending on Differentiation Route of SH-SY5Y Cells
Abstract: Alzheimer’s disease (AD) is a currently incurable neurodegenerative disorder being the major form of dementia worldwide. AD pathology is initiated by cerebral aggregation of amyloid-β (Aβ) peptides in the form of amyloid plaques; however, the mechanism how Aβ peptide aggregates participate in the disease progression and neurodegeneration is still under debate. Human neuroblastoma cell line SH-SY5Y is a convenient cellular model, which is widely used in biochemical and toxicological studies of neurodegenerative diseases. This model can be further improved by differentiation of the cells toward more neuron-like culture using different protocols. In the current study, dbcAMP, retinoic acid with TPA, or BDNF were used for differentiation of SH-SY5Y cells, and the resulting cultures were tested for the toxicity toward the Aβ42 peptide. The toxicity of Aβ42 peptide depended on the type of differentiated cells: RA and TPA- differentiated cells were most resistant, whereas dbcAMP and RA/BDNF- differentiated cells were more sensitive to Aβ toxicity as compared with non-differentiated cells. The differentiated cultures provide more appropriate cellular models of human origin that can be used for studies of the mechanism of Aβ pathogenesis and for a screening of compounds antagonistic to the toxicity of Aβ peptides.
Viviana Bonfiglio, Hiroyuki Umegaki, Masafumi Kuzuya (Handling Associate Editor: Bertrand Fougère)
Potentially Inappropriate Medications and Polypharmacy: A Study of Older People with Mild Cognitive Impairment and Mild Dementia
Abstract: Background: With multimorbidity increasing among older people, polypharmacy and the use of potentially inappropriate medications (PIMs) are assuming a prominent role in the life of the geriatric population. Objective: To investigate the association of polypharmacy and PIM use with a wide range of factors in older people with mild cognitive impairment (MCI) to mild dementia. Methods: The study population comprised 160 outpatients with a Clinical Dementia Rating of 0.5-1 and a Mini-Mental State Examination score of 20-30. Patients were classified as receiving polypharmacy when they took ≥ 5 different medications at the same time. PIMs were identified using the STOPP-J criteria. Cognitive, neuropsychological, nutritional, and physical function tests were performed and body measurements taken. Quality of life (QOL) was assessed using both components of the EQ-5D scale, the index score, and the visual analogue scale (QOL VAS). A comorbidity index was calculated for all participants. Results: PIM use was significantly associated with lower scores on the verbal fluency (initial letters) test and QOL index. Participants receiving polypharmacy showed an increased likelihood of worse frailty status and lower QOL VAS score. The number of medications was significantly associated with worse frailty status. Conclusion: In a geriatric population with MCI to mild dementia, PIM use was associated with lower verbal fluency (initial letters) score and lower QOL, while the presence of polypharmacy was correlated with a worse frailty status and lower QOL. The number of medicines, instead, was correlated with a worse frailty status only.
Jung-Min Pyun, Min Ju Kang, Young Chul Youn, Young Ho Park, SangYun Kim (Handling Associate Editor: YongSoo Shim)
Depressive Symptoms and Cognitive Improvement in Patients with Dementia with Lewy Bodies
Abstract: Background: Although dementia with Lewy bodies (DLB) is a degenerative disease involving irreversible pathological changes and subsequent progressive cognitive decline, some patients have presented with improved cognitive function at follow-ups. Their clinical and neuropsychological characteristics and the factors influencing this improvement remain unclear. Objective: To investigate differences in clinical and neuropsychological characteristics between DLB patients with and without cognitive improvement at a one-year follow-up, and to identify predictive factors of cognitive improvement. Methods: This retrospective study included 60 DLB patients, 28 patients in the improved group, and 32 patients in the non-improved group. A multiple linear regression model was used to compare changes in cognitive function test scores between groups over the course of one year. Binary logistic regression analysis was performed to determine the odds ratios (ORs) of depressive symptoms as a predictor for cognitive improvement. Results: The improved group showed significant increases in immediate and delayed verbal memory function in one year over the non-improved group. We also found that baseline depressive symptoms were associated with an increased probability of cognitive improvement (OR 1.234, CI 1.043–1.460). Conclusion: Depressive symptoms at baseline were related to a higher probability of a cognitive improvement at one-year follow-up. In addition, immediate and delayed verbal memory function showed significant improvement during one year in improved patients compared to non-improved patients.
Michela Guglielmotto, Ivan Enrico Repetto, Debora Monteleone, Valeria Vasciaveo, Claudio Franchino, Sara Rinaldi, Massimo Tabaton, Elena Tamagno
Stroke and Amyloid-β Downregulate TREM-2 and Uch-L1 Expression that Synergistically Promote the Inflammatory Response
Abstract: Neuroinflammation is involved in the pathogenesis of Alzheimer’s disease, and the transcription factor NF-κB is a player in this event. We found here that the ischemic damage alone or in association with Aβ1-42 activates the NF-κB pathway, induces an increase of BACE1 and a parallel inhibition of Uch-L1 and TREM2, both in vitro and in vivo, in Tg 5XFAD and in human brains of sporadic AD. This mechanism creates a synergistic loop that fosters inflammation. We also demonstrated a significant protection exerted by the restoration of Uch-L1 activity. The rescue of the enzyme is able to abolish the decrease of TREM2 and the parameters of neuroinflammation.
Patrick J. Smith, Stephanie Mabe, Andrew Sherwood, Michael A. Babyak, P. Murali Doraiswamy, Kathleen A. Welsh-Bohmer, William Kraus, James Burke, Alan Hinderliter, James A. Blumenthal
Association Between Insulin Resistance, Serum Leptin, and Neurocognition in Vascular Cognitive Impairment
Abstract: Background: Greater body weight has been associated impairments in neurocognition and greater dementia risk, although the mechanisms linking weight and neurocognition have yet to be adequately delineated. Objective: To examine metabolic mechanisms underlying the association between obesity and neurocognition. Methods: We conducted a secondary analysis of weight, neurocognition, and the potentially mediating role of metabolic and inflammatory biomarkers among 160 participants from the ENLIGHTEN trial of vascular cognitive impairment, no dementia (CIND). Neurocognition was assessed using a 45-minute assessment battery assessing Executive Function, Verbal and Visual Memory. We considered three metabolic biomarkers: insulin resistance (homeostatic model assessment [HOMA-IR]), plasma leptin, and insulin-like growth factor (IGF-1). Inflammation was assessed using C-reactive protein. Multiple regression analyses were used. Results: Participants included 160 sedentary older adults with CIND. Participants tended to be overweight or obese (mean BMI = 32.5 [SD = 4.8]). Women exhibited higher BMI (p = 0.043), CRP (p < 0.001), and leptin (p < 0.001) compared with men. Higher BMI levels were associated with worse performance on measures of Executive Function (β = -0.16, p = 0.024) and Verbal Memory (β = -0.16, p = 0.030), but not Visual Memory (β = 0.05, p = 0.500). Worse metabolic biomarker profiles also were associated with lower Executive Function (β = -0.12, p = 0.050). Mediation analyses suggested leptin was a plausible candidate as a mediator between BMI and Executive Function. Conclusions: In overweight and obese adults with vascular CIND, the association between greater weight and poorer executive function may be mediated by higher leptin resistance.
Katherine J. Bangen, Nicole M. Armstrong, Rhoda Au, Alden L. Gross (Handling Associate Editor: Jason Brandt)
Metabolic Syndrome and Cognitive Trajectories in the Framingham Offspring Study
Abstract: Metabolic syndrome (MetS) has been linked to increased risk of developing cognitive impairment and dementia including Alzheimer’s disease. It remains unclear whether and at what stage in the adult lifespan MetS and its components begin to alter the trajectory of cognitive performance. In the present study, 2,892 Framingham Offspring participants completed health assessments every four years since 1971 and underwent repeat neuropsychological testing from 1999 to 2014. We estimated the associations of levels and changes in cognitive trajectories with hazard of MetS using a joint growth/survival model. All models were adjusted for baseline age, sex, education, and smoking status. Findings showed that both mid-life and late-life MetS were associated with lower level of cognitive functioning but not cognitive trajectories. Associations were strongest among those who were nondemented and apolipoprotein (APOE) ε4 noncarriers. In addition, individuals with the most rapid cognitive decline were more likely to have MetS. The pattern of results showed that associations between MetS and cognition varied, depending upon whether the sample was stratified by genetic and cognitive status and whether we considered cognitive performance as a continuous variable or examined categorical groupings. Given that mid-life MetS was associated with poorer cognition at age 55, cognitive changes may occur early during the MetS process. Our findings suggest that those with MetS are at greater risk of dementia given their lower level of cognitive functioning and also suggest that MetS may be a risk factor for decline in the absence of known risk factors including the APOE ε4 allele.
Alex J.T. Yang, Scott Frendo-Cumbo, Rebecca E.K. MacPherson
Resveratrol and Metformin Recover Prefrontal Cortex AMPK Activation in Diet-Induced Obese Mice but Reduce BDNF and Synaptophysin Protein Content
Abstract: Background: Obesity, insulin resistance, and type 2 diabetes are established risk factors for the development of Alzheimer’s disease (AD). Given this connection, two drugs, metformin (MET) and resveratrol (RESV), are considered for the clearance of amyloid-β peptides through AMPK-mediated activation of autophagy. However, overactivation of AMPK observed in late-stage AD brains and relationships between AMPK and neurogenesis (through mTORC1 inhibition), questions treatment with these drugs. Objective: To examine if MET and/or RESV supplementation activates brain AMPK, regulates markers of autophagy, and affects markers of neuronal health/neurogenesis. Methods: 8-week-old male C57BL/6J mice were fed a low (N=12; 10%kcal fat; LFD) or high fat diet (N=40; 60%kcal fat; HFD) for 9 weeks to induce insulin resistance and obesity. HFD mice were then treated with/without MET (250 mg/kg/day), RESV (100 mg/kg/day), or COMBO (MET: 250 mg/kg/day, RESV: 100 mg/kg/day) for 5 weeks. Hippocampus and prefrontal cortex were extracted for western blotting analysis. Results: Cortex AMPK (T172) and raptor (S792, the regulatory subunit of mTORC1) phosphorylation were upregulated following RESV, COMBO treatments. mTOR (S2448) and ULK1 (S555) activation was seen following MET, COMBO and RESV, COMBO treatments, respectively, in the cortex and hippocampus. p62 content was decreased following RESV, COMBO, with LC3 content being increased following RESV treatment in the cortex. Brain derived neurotropic factor (BDNF) was significantly decreased following RESV, COMBO, and synaptophysin following all treatment in the cortex. Conclusion: These results demonstrate that while treatments upregulated markers of autophagy in the prefrontal cortex, reductions in neuronal health markers question the efficacy of AMPK as a therapy for AD.
Ambar Kulshreshtha, Margarethe Goetz, Alvaro Alonso, Amit J. Shah, J. Douglas Bremner, Jack Goldberg, Viola Vaccarino
Association Between Cardiovascular Health and Cognitive Performance: A Twins Study
Abstract: Background/Objective: The 2020 Strategic Impact Goal introduced by the American Heart Association (AHA) aims at improving cardiovascular health (CVH) of all Americans by 20%. AHA defined ideal CVH across seven established modifiable risk factors for cardiovascular diseases. Prior studies have indicated that ideal CVH also benefits brain health and cognitive aging, but it is possible that this association is explained by familial factors. Methods: We examined 272 male monozygotic and dizygotic twin pairs (total 544 subjects) free of overt cardiovascular disease and dementia from the Vietnam Era Twin Registry. Memory and learning were measured by Trail Making tests and Wechsler Memory Scale (Immediate and Delayed Memory tests and Visual Reproductive Test). Each of the seven CVH components (smoking, body mass index, physical activity, diet, total cholesterol, blood pressure, and blood glucose) was scored per established criterion. Results: The mean age of the twins was 55 years, 96% were whites, and 61% monozygotic. When considering twins as individuals, for every unit increase in CVH score (indicating better cardiovascular health), twins demonstrated faster cognitive processing speed (Trail B: -5.6 s, 95%CI -10.3, -0.9; p=0.03) and better story recall, both immediate (0.35, 95%CI 0.06, 0.62; p=0.02) and delayed (0.39, 95%CI 0.08, 0.70; p=0.01). Conclusions: Better CVH is associated with better cognitive health in several domains. As suggested by within-pair analysis, this association is largely explained by familial factors, implying that early life exposures are shared determinants of both brain health and cardiovascular health.
Maria Skaalum Petersen, Marjun Restorff, Tórmóður Stórá, Gunhild Waldemar, Sofus Joensen
Trend in the Incidence and Prevalence of Dementia in the Faroe Islands
Abstract: Background: Dementia has become an important public health, economic, and social issue. Knowledge about prevalence, incidence, and trends of dementia in a country is of crucial importance. However, no studies of prevalence or incidence of dementia have been undertaken in the Faroe Islands. Objectives: The aim was to estimate the overall and trend in incidence and prevalence of dementia among individuals ≥60 years in the Faroe Islands from 2010-2017. Methods: Population-based register study where all individuals ≥60 years with a dementia diagnosis from January 2010 to December 2017 were identified. The overall crude and age‐and-sex‐specific prevalence and incidence was assessed. Results: The overall crude incidence among individuals ≥60 years from 2010 to 2017 was 5.1 per 1000 individuals and the prevalence 22.5 per 1000 individuals. The age-and sex-standardized annual incidence of dementia fluctuated between 4.8 and 6.7 per 1000, with no clear secular trend while the age-and sex-standardized prevalence increased steadily from 14.5 in 2010 to 30.8 per 1000 individuals in 2017. Conclusion: The age-standardized prevalence and incidence estimates in the Faroes seem to be lower than in other countries. The incidence was relatively stable in the period while the prevalence of dementia simultaneously increased.
Carol J. Huseby*, Claire N. Hoffman*, Grace L. Cooper, Jean-Christophe Cocuron, Ana P. Alonso, Stefani N. Thomas, Austin J. Yang, Jeff Kuret *These authors contributed equally to this work.
Quantification of Tau Protein Lysine Methylation in Aging and Alzheimer’s Disease
Abstract: Tau is a microtubule-associated protein that normally interacts in monomeric form with the neuronal cytoskeleton. In Alzheimer’s disease, however, it aggregates to form the structural component of neurofibrillary lesions. The transformation is controlled in part by age- and disease-associated post-translational modifications. Recently we reported that tau isolated from cognitively normal human brain was methylated on lysine residues, and that high-stoichiometry methylation depressed tau aggregation propensity in vitro. However, whether methylation stoichiometry reached levels needed to influence aggregation propensity in human brain was unknown. Here we address this problem using liquid chromatography–tandem mass spectrometry approaches and human-derived tau samples. Results revealed that lysine methylation was present in soluble tau isolated from cognitively normal elderly cases at multiple sites that only partially overlapped with the distributions reported for cognitively normal middle aged and AD cohorts, and that the quality of methylation shifted from predominantly dimethyl-lysine to monomethyl-lysine with aging and disease. However, bulk mol methylation/mol tau stoichiometries never exceeded 1 mol methyl group/mol tau protein. We conclude that lysine methylation is a physiological post-translational modification of tau protein that changes qualitatively with aging and disease, and that pharmacological elevation of tau methylation may provide a means for protecting against pathological tau aggregation.
Isabella Wiest*, Tim Wiemers*, Max-Joseph Kraus*, Heiko Neeb, Erwin F. Strasser, Lucrezia Hausner, Lutz Frölich*, Peter Bugert* *These authors contributed equally to this work.
Multivariate Platelet Analysis Differentiates Between Patients with Alzheimer’s Disease and Healthy Controls at First Clinical Diagnosis
Abstract: Background: Early diagnosis of Alzheimer’s disease (AD) is challenging, and easily accessible biomarkers are an unmet need. Blood platelets frequently serve as peripheral model for studying AD pathogenesis and might represent a reasonable biomarker source. Objective: In the present study, we investigated the potential to differentiate AD patients from healthy controls (HC) based on blood count, platelet morphology, and function as well as molecular markers at the time of first clinical diagnosis. Methods: Blood samples from 40 AD patients and 29 age-matched HC were included for determination of 78 parameter by blood counting, platelet morphometry, aggregometry, flow cytometry (CD62P, CD63, activated fibrinogen receptor), protein quantification of nicotinic acetylcholine receptor α7 (nAChRα7) and caveolin-1 (CAV-1), and miRNA quantification (miR-26b, miR-199a, miR-335). Group comparison between patients and controls was performed in univariate and multivariate statistical analyses. Results: AD patients showed significantly lower aggregation response to ADP and arachidonic acid and significantly decreased CD62P and CD63 surface expression induced by ADP and U46619 compared to HC. Relative nAChRα7 and CAV-1 expression was significantly higher AD platelets than in HC. Multivariate analysis of 63 parameter revealed significant differences between AD patients and healthy controls. The best performing feature model revealed a sensitivity of 96.6%, a specificity of 80.0%, and a positive predictive value of 89.3%. No grouping could be achieved by using single parameter groups. Conclusion: Significant differences between platelet characteristics from AD patients and HC at the time of first clinical diagnosis were observed. The best performing parameter can be used as a blood-based biomarker for AD diagnosis in a multivariate model in addition to the standardized mental tests.
Vaisakh Puthusseryppady, Gillian Coughlan, Martyn Patel, Michael Hornberger (Handling Associate Editor: Sharon Naismith)
Geospatial Analysis of Environmental Risk Factors for Missing Dementia Patients
Abstract: Background: Dementia-related missing incidents are highly prevalent but still poorly understood. This is particularly true for environmental/geospatial risk factors, which might contribute to these missing incidents. Objective: The study aimed to conduct a retrospective, observational analysis on a large sample of missing dementia patient case records provided by the police (n = 210), covering dates from January 2014 to December 2017. In particular, we wanted to explore 1) whether there were any hotspot regions of missing incidents and 2) the relationship between outdoor landmark density and missing incidents. Methods: Global spatial autocorrelation (Moran’s I) was used to identify the potential hotspot regions for missing incidents. Meanwhile, spatial buffer and regression modelling were used to determine the relationship between outdoor landmark density and missing incidents. Results: Our demographics measures replicated and extended previous studies of dementia-related missing incidents. Meanwhile, no hotspot regions for missing incidents were identified, while higher outdoor landmark density leads to increased missing incidents. Conclusion: Our results highlight that missing incidents do not occur in isolated hotspots of regions but instead are endemic in patients regardless of location. Higher outdoor landmark density emerges as a significant geospatial factor for missing incidents in dementia, which crucially informs future safeguarding/intervention studies.
Rachel M. Shaffer, Lianne Sheppard, Elaine R. Peskind, Jing Zhang, Sara D. Adar, Ge Li
Fine Particulate Matter Exposure and Cerebrospinal Fluid Markers of Vascular Injury
Abstract: Background: Cerebrovascular diseases play an important role in dementia. Air pollution is associated with cardiovascular disease, with growing links to neurodegeneration. Prior studies demonstrate associations between fine particulate matter (PM2.5) and biomarkers of endothelial injury in the blood; however, no studies have evaluated these biomarkers in cerebrospinal fluid (CSF). Objective: We evaluate associations between short-term and long-term PM2.5 exposure with CSF vascular cell adhesion molecule-1 (VCAM-1) and e-selectin in cognitively normal and mild cognitive impairment (MCI)/Alzheimer’s disease (AD) individuals. Methods: We collected CSF from 133 community volunteers at VA Puget Sound between 2001-2012. We assigned short-term PM2.5 from central monitors and long-term PM2.5 based on annual average exposure predictions linked to participant addresses. We performed analyses stratified by cognitive status and adjusted for key covariates with tiered models. Our primary exposure windows for the short-term and long-term analyses were 7-day and 1-year averages, respectively. Results: Among cognitively normal individuals, a 5 µg/m3 increase in 7-day and 1-year average PM2.5 was associated with elevated VCAM-1 (7-day: 35.4 (9.7, 61.1) ng/ml; 1-year: 51.8 (6.5, 97.1) ng/ml). A 5 µg/m3 increase in 1-year average PM2.5, but not 7-day average, was associated with elevated e-selectin (53.3 (11.0, 95.5) pg/ml). We found no consistent associations among MCI/AD individuals. Conclusions: We report associations between short-term and long term PM2.5 and CSF biomarkers of vascular damage in cognitively normal adults. These results are aligned with prior research linking PM2.5 to vascular damage in other biofluids as well as emerging evidence of the role of PM2.5 in neurodegeneration.
Ali Ezzati, Andrea R. Zammit, Danielle J. Harvey, Christian Habeck, Charles B. Hall, Richard B. Lipton, for the Alzheimer’s Disease Neuroimaging Initiative
Optimizing Machine Learning Methods to Improve Predictive Models of Alzheimer’s Disease
Abstract: Background: Predicting clinical course of cognitive decline can boost clinical trials’ power and improve our clinical decision-making. Machine learning (ML) algorithms are specifically designed for the purpose of prediction; however. identifying optimal features or algorithms is still a challenge. Objective: To investigate the accuracy of different ML methods and different features to classify cognitively normal (CN) individuals from Alzheimer’s disease (AD) and to predict longitudinal outcome in participants with mild cognitive impairment (MCI). Methods: A total of 1,329 participants from the Alzheimer's Disease Neuroimaging Initiative (ADNI) were included: 424 CN, 656 MCI, and 249 AD individuals. Four feature-sets at baseline (hippocampal volume and volume of 47 cortical and subcortical regions with and without demographics and APOE4) and six machine learning methods (decision trees, support vector machines, K-nearest neighbor, ensemble linear discriminant, boosted trees, and random forests) were used to classify participants with normal cognition from participants with AD. Subsequently the model with best classification performance was used for predicting clinical outcome of MCI participants. Results: Ensemble linear discriminant models using demographics and all volumetric magnetic resonance imaging measures as feature-set showed the best performance in classification of CN versus AD participants (accuracy=92.8%, sensitivity=95.8%, and specificity=88.3%). Prediction accuracy of future conversion from MCI to AD for this ensemble linear discriminant at 6, 12, 24, 36, and 48 months was 63.8% (sensitivity=74.4, specificity=63.1), 68.9% (sensitivity=75.9, specificity=67.8), 74.9% (sensitivity=71.5, specificity=76.3), 75.3%, (sensitivity=65.2, specificity=79.7), and 77.0% (sensitivity=59.6, specificity=86.1), respectively. Conclusions: Machine learning models trained for classification of CN versus AD can improve our prediction ability of MCI conversion to AD.
Arnaud Charil, Sergey Shcherbinin, Sudeepti Southekal, Michael D. Devous, Sr., Mark Mintun, Melissa E. Murray, Bradley B. Miller, Adam J. Schwarz
Tau Subtypes of Alzheimer’s Disease Determined in vivo Using Flortaucipir PET Imaging
Abstract: At autopsy, individuals with Alzheimer’s disease (AD) exhibit heterogeneity in the distribution of neurofibrillary tangles in neocortical and hippocampal regions. Subtypes of AD, defined using an algorithm based on the relative number of tangle counts in these regions, have been proposed—hippocampal sparing (relative sparing of the hippocampus but high cortical load), limbic predominant (high hippocampal load but lower load in association cortices), and typical (balanced neurofibrillary tangles counts in the hippocampus and association cortices) AD—and shown to be associated with distinct antemortem clinical phenotypes. The ability to distinguish these AD subtypes from the more typical tau signature in vivo could have important implications for clinical research. Flortaucipir positron emission tomography (PET) images acquired from 45 amyloid-positive participants, defined clinically as mild cognitive impairment or AD, aged 50-92 years, 56% female, and estimated to be Braak V-VI based on their PET pattern of tau pathology, were studied. By translating the neuropathologic algorithm to flortaucipir PET scans, patterns of tau pathology consistent with autopsy findings, and with a similar prevalence, were identified in vivo. 6/45 (13%) participants were identified as hippocampal sparing and 6/45 (13%) as limbic predominant AD subtypes. Hippocampal sparing participants were significantly younger than those assigned to the other two subtypes. Worse performance on delayed recall was associated with increased hippocampal tau signal, and worse performance on the trail making test B-A was associated with lower values of the hippocampus to cortex ratio. Prospective studies can further validate the flortaucipir SUVR cut-points and the phenotype of the corresponding AD subtypes.
Naiara Aguirre*, Víctor Costumero*, Lidón Marin-Marin, Joaquín Escudero, Vicente Belloch, María Antonia Parcet, César Ávila (Handling Associate Editor: Roser Sala-Llonch) *These authors contributed equally to this work.
Activity in Memory Brain Networks During Encoding Differentiates Mild Cognitive Impairment Converters from Non-Converters
Abstract: Alzheimer’s disease (AD) has been associated with memory impairment due to alterations in the medial temporal lobe (MTL) and the precuneus. Therefore, the goal of this study was to investigate the effects of AD on the brain networks associated with the hippocampus and precuneus during an encoding memory task. 68 mild cognitive impairment patients (MCI), 21 AD patients, and 20 healthy controls (HC) were included. Participants were instructed to memorize landscapes while undergoing fMRI scanning, followed by a recognition test. MCI were followed up clinically for 18 months to track conversion status. Independent component analysis (ICA) was performed to investigate AD effects on precuneus and MTL networks during memory encoding. Behavioral analyses indicate that HC had a better performance than MCI converters (MCIc) and AD. ICA showed that MCIc had significantly higher activation in the MTL-associated network than MCI non converters (MCIn) and AD, including bilateral hippocampus, parahippocampus, and fusiform gyrus. Furthermore, the precuneus-associated network fitted the default mode network, showing a negative correlation with behavioral performance. These findings indicate that the hyperactivation of the hippocampal network displayed by MCIc has potential discrimination capacity to distinguish them of MCIn, and could be interpreted as a compensatory mechanism.
Koh Tadokoro*, Ryuta Morihara*, Yasuyuki Ohta, Nozomi Hishikawa, Satoko Kawano, Ryo Sasaki, Namiko Matsumoto, Emi Nomura, Yumiko Nakano, Yoshiaki Takahashi, Mami Takemoto, Toru Yamashita, Setsuko Ueno, Yosuke Wakutani, Yoshiki Takao, Nobutoshi Morimoto, Yumiko Kutoku, Yoshihide Sunada, Katsushi Taomoto, Yasuhiro Manabe, Kentaro Deguchi, Yasuto Higashi, Haruhiko Inufusa, Fukka You, Toshikazu Yoshikawa, Markus Matuschka von Greiffenclau, Koji Abe (Handling Associate Editor: Yusuke Seino) *These authors contributed equally to this work.
Clinical Benefits of Antioxidative Supplement Twendee X for Mild Cognitive Impairment: A Multicenter, Randomized, Double-Blind, and Placebo-Controlled Prospective Interventional Study
Abstract: Oxidative stress is part of the entire pathological process that underlies the development of Alzheimer’s disease (AD), including the mild cognitive impairment (MCI) stage. Twendee X (TwX) is a supplement containing a strong antioxidative mix of eight antioxidants, which has been shown to have a clinical and therapeutic benefit in AD model mice. Here, we conducted a multicenter, randomized, double-blind, and placebo-controlled prospective interventional study to evaluate the efficacy of TwX in mitigating MCI. The primary outcomes were differences in Mini-Mental State Examination (MMSE) and Hasegawa Dementia Scale-revised (HDS-R) scores between baseline and six months for placebo and TwX groups. Seventy-eight subjects with MCI were randomized into placebo (n = 37) and TwX (n = 41) groups. MMSE scores at six months differed significantly between the TwX and placebo groups (p = 0.018), and HDS-R scores for the TwX group exhibited a significant improvement at six months relative to baseline (p = 0.025). The TwX group did not show any change in affective or activities of daily living scores at six months. The present study indicates that strong antioxidative supplement TwX is clinical beneficial for cognitive function in subjects with MCI.