Association between dietary inflammatory index score and incident dementia: results from the Framingham heart Study offspring cohort.

Background: The Dietary Inflammatory Index (DII), has been specifically designed to capture the inflammatory content of diet and has shown association with neurodegenerative disease related outcomes. But literature is limited on the role of diet-driven inflammation measured by the DII on incident all-cause dementia and Alzheimer's disease dementia (AD). Objective: We evaluated whether higher DII scores were associated with increased incidence of all-cause dementia and AD over 22.3 years of follow-up in the community-based Framingham Heart Study (FHS) Offspring cohort. Design Setting and Participants: Observational longitudinal study in the FHS Offspring cohort. Dementia surveillance for present study: until 2020. Data were analyzed from December 2020 to June 2022. Participants completed a validated 126-item food frequency questionnaires (FFQ), administered at FHS examination cycle 7 (1998-2001) and examination cycle 5 (1991-1995), and/or 6 (1995-1998). Individuals aged <60 years, with prevalent dementia, no dementia follow-up, other relevant neurological diseases, and/or no FFQ data were excluded. Exposure: A DII score (based on the published method by Shivappa et al. 2014) was created based on previous studies linking individual dietary factors to six inflammatory markers (i.e. C-reactive protein, interleukin (IL)-1ß, IL-4, IL-6, IL-10, and tumor necrosis factor-alpha), consisting of 36 components. A cumulative DII score was calculated by averaging across a maximum of three FFQs. Main outcomes and measures: Incident all-cause dementia and AD. Results: We included 1487 participants (mean±SD, age in years 69 ± 6; 53·2% women; 31·6% college graduates]). 246 participants developed all-cause dementia (including AD n=187) over a median follow up time of 13·1 years. Higher DII scores were associated with an increased incidence of all-cause dementia and AD following adjustment for age and sex (Hazard ratio (HR) 1·16, 95% confidence interval (CI) 1·07 to 1·25, p<.001; HR 1·16, 95% CI 1·06 to 1·26, p=.001). The relationships remained after additional adjustment for demographic, lifestyle, and clinical covariates (HR 1·21, 95% CI 1·10 to 1·33, p<0.001; HR1·20, 95% CI1·07 to 1·35, p=.001). Conclusion and relevance: Higher DII scores were associated with a higher risk of incident all-cause dementia and AD. Although these promising findings need to be replicated and further validated, our results suggest that diets which correlate with low DII scores may prevent late-life dementia.

The Brain Health Imperative in the 21st Century-A Call to Action: The AAN Brain Health Platform and Position Statement.

Brain health is crucial to optimizing both the function and well-being of every person at each stage of life and is key to both individual and social progress. As a concept, brain health is complex and requires a multidisciplinary collaborative approach between many professional and public organizations to bring into effect meaningful change. Neurologists are uniquely positioned to serve as specialists in brain health and to advance the newly evolving field of preventive neurology, which aims to identify individuals at high risk of brain disorders and other neurologic conditions and offer strategies to mitigate disease emergence or progression. For decades, the American Academy of Neurology (AAN) has demonstrated a commitment to brain health through its public outreach and advocacy. The AAN's Brain Health Initiative launched in 2022 with a strategic plan prioritizing brain health as a key aspect of public engagement and positioning the AAN and neurologists as champions of brain health in collaboration with a broad range of other brain health providers. In this study, we present (1) the new definition of brain health developed by the AAN for neurologists, patients, partners in health care, and the public; (2) the strategic objectives of the AAN Brain Health Initiative; and (3) the AAN Brain Health Platform and Action Plan framework, including key positions on brain health, its 3 ambitious goals, and a national brain health vision. The top-line priorities of the AAN Brain Health Action Plan highlight the need for research, education, public policy, and direct-to-public messaging across the individual's life span and will serve as a catalyst for future cross-disciplinary collaborations within each epoch and longitudinally. The AAN Brain Health Platform is designed to communicate the AAN's vision for brain health and provide a blueprint toward achieving the future of optimal brain health across the life span for all. Through this position statement, we call upon neurologists and other stakeholders in brain health to join our collective efforts to accomplish the ultimate goal of transforming the current trajectory of public health of an increasing burden of neurologic disorders-from both illness and injury-to achieving optimal brain health for all.

Decoding information about cognitive health from the brainwaves of sleep.

Sleep electroencephalogram (EEG) signals likely encode brain health information that may identify individuals at high risk for age-related brain diseases. Here, we evaluate the correlation of a previously proposed brain age biomarker, the "brain age index" (BAI), with cognitive test scores and use machine learning to develop and validate a series of new sleep EEG-based indices, termed "sleep cognitive indices" (SCIs), that are directly optimized to correlate with specific cognitive scores. Three overarching cognitive processes were examined: total, fluid (a measure of cognitive processes involved in reasoning-based problem solving and susceptible to aging and neuropathology), and crystallized cognition (a measure of cognitive processes involved in applying acquired knowledge toward problem-solving). We show that SCI decoded information about total cognition (Pearson's r = 0.37) and fluid cognition (Pearson's r = 0.56), while BAI correlated only with crystallized cognition (Pearson's r = - 0.25). Overall, these sleep EEG-derived biomarkers may provide accessible and clinically meaningful indicators of neurocognitive health.

Ceiling effects and differential measurement precision across calibrated cognitive scores in the Framingham Study.

OBJECTIVE: To calibrate cognitive assessment data across multiple waves of the Framingham Heart Study (FHS), addressing study design considerations, ceiling effects, and measurement precision. METHOD: FHS participants completed several cognitive assessments including screening instruments and more comprehensive batteries at different study visits. We used expert opinion to assign each cognitive test item to a single domain-memory, executive function, language, visuospatial abilities, or none of the above. As part of a larger cross-study harmonization effort, we calibrated each domain separately using bifactor confirmatory factor analysis (CFA) models, incorporating item parameters for anchor items previously calibrated from other studies and freely estimating item parameters for FHS-specific items. We obtained scores and standard errors (SEs) for each participant at each study visit. We addressed psychometric considerations of ceiling effects and measurement precision. RESULTS: Overall, memory domain scores were the most precisely estimated. Scores for all domains from visits where the Mini-Mental State Examination (MMSE) was the only test administered were imprecisely estimated and suffered from ceiling effects. Scores from visits with a more extensive battery were estimated more precisely and better differentiated between ability levels. CONCLUSIONS: The harmonized and calibrated cognitive data from the FHS should prove useful for future analyses examining cognition and cognitive decline. They will be of particular interest when combining FHS with other studies that have been similarly calibrated. Researchers should be aware of varying levels of measurement precision and the possibility of ceiling effects in their planned analyses of data from the FHS and similar studies. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Non-Pharmacologic Interventions for Hispanic Caregivers of Persons with Dementia: Systematic Review and Meta-Analysis.

BACKGROUND: As the Hispanic/Latino (HL) population grows, so too does the need for HL family caregivers for persons with dementia. HL caregivers tend to have less education, lower health literacy, and lower income, each uniquely compounding burden. Research is needed to appropriately tailor interventions for this population. OBJECTIVE: A systematic review and meta-analysis was conducted to 1) provide an updated review of non-pharmacologic intervention studies for HL dementia caregivers, 2) characterize promising interventions, and 3) highlight opportunities for future research. METHODS: Databases were searched for articles evaluating non-pharmacologic interventions for HL dementia caregivers. Studies were excluded if target populations did not include HLs or if no intervention was delivered. Data were extracted and random effects meta-analysis was performed on two primary outcomes: caregiver depression and burden. Effect sizes were calculated as pre- and post-intervention standardized mean differences (SMD), and further depression subgroup meta-analysis was performed. Other secondary outcome measures (e.g., perceived social support, caregiver knowledge, anxiety) were evaluated qualitatively. RESULTS: Twenty-three studies were identified. Most included multiple components pertaining to psychosocial support, caregiver education, and community resource facilitation. Many studies were successful in improving caregiver outcomes, though intervention design varied. Meta-analysis revealed minimal to moderate heterogeneity and small effect size in improving depressive symptoms (SMD = -0.31, 95% CI -0.46 to -0.16; I2 = 50.16%) and burden (SMD = -0.28, 95% CI -0.37 to -0.18; I2 = 11.06%). CONCLUSION: Although intervention components varied, many reported outcome improvements. Future studies may benefit from targeting physical health, addressing sociocultural and economic contexts of caregivers, and leveraging technology.

Platelet Function Is Associated With Dementia Risk in the Framingham Heart Study.

Background Vascular function is compromised in Alzheimer disease (AD) years before amyloid and tau pathology are detected and a substantial body of work shows abnormal platelet activation states in patients with AD. The aim of our study was to investigate whether platelet function in middle age is independently associated with future risk of AD. Methods and Results We examined associations of baseline platelet function with incident dementia risk in the community-based FHS (Framingham Heart Study) longitudinal cohorts. The association between platelet function and risk of dementia was evaluated using the cumulative incidence function and inverse probability weighted Cox proportional cause-specific hazards regression models, with adjustment for demographic and clinical covariates. Platelet aggregation response was measured by light transmission aggregometry. The final study sample included 1847 FHS participants (average age, 53.0 years; 57.5% women). During follow-up (median, 20.5 years), we observed 154 cases of incident dementia, of which 121 were AD cases. Results from weighted models indicated that platelet aggregation response to adenosine diphosphate 1.0 µmol/L was independently and positively associated with dementia risk, and it was preceded in importance only by age and hypertension. Sensitivity analyses showed associations with the same directionality for participants defined as adenosine diphosphate hyper-responders, as well as the platelet response to 0.1 µmol/L epinephrine. Conclusions Our study shows individuals free of antiplatelet therapy with a higher platelet response are at higher risk of dementia in late life during a 20-year follow-up, reinforcing the role of platelet function in AD risk. This suggests that platelet phenotypes may be associated with the rate of dementia and potentially have prognostic value.

Association of Loneliness With 10-Year Dementia Risk and Early Markers of Vulnerability for Neurocognitive Decline.

BACKGROUND AND OBJECTIVES: Loneliness is common, and its prevalence is rising. The relationship of loneliness with subsequent dementia and the early preclinical course of Alzheimer disease and related dementia (ADRD) remains unclear. Thus, the primary objective of this study was to determine the association of loneliness with 10-year all-cause dementia risk and early cognitive and neuroanatomic imaging markers of ADRD vulnerability. METHODS: This was a retrospective analysis of prospectively collected data from the population-based Framingham Study cohorts (September 9, 1948-December 31, 2018). Eligible participants had loneliness assessed and were dementia-free at baseline. Loneliness was recorded with the Center for Epidemiologic Studies Depression Scale, defined conservatively as feeling lonely ≥3 days in the past week. The main outcomes were incident dementia over a 10-year period, cognition, and MRI brain volumes and white matter injury. RESULTS: Of 2,308 participants (mean age 73 [SD 9] years, 56% women) who met eligibility in the dementia sample, 14% (329 of 2,308) developed dementia and 6% (144 of 2,308) were lonely. Lonely (versus not lonely) adults had higher 10-year dementia risk (age-, sex-, and education-adjusted hazard ratio 1.54, 95% CI 1.06-2.24). Lonely participants <80 years of age without APOE ε4 alleles had a 3-fold greater risk (adjusted hazard ratio 3.03, 95% CI, 1.63-5.62). Among 1,875 persons without dementia who met eligibility in the cognition sample (mean age 62 [SD 9] years, 54% women), loneliness associated with poorer executive function, lower total cerebral volume, and greater white matter injury. DISCUSSION: Over 10 years of close clinical dementia surveillance in this cohort study, loneliness was associated with increased dementia risk; this tripled in adults whose baseline risk would otherwise be relatively low on the basis of age and genetic risk, representing a majority of the US population. Loneliness was also associated with worse neurocognitive markers of ADRD vulnerability, suggesting an early pathogenic role. These findings may have important clinical and public health implications given observed loneliness trends. CLASSIFICATION OF EVIDENCE: This study provides Class I evidence that loneliness increases the 10-year risk of developing dementia.

Optimal spindle detection parameters for predicting cognitive performance.

STUDY OBJECTIVES: Alterations in sleep spindles have been linked to cognitive impairment. This finding has contributed to a growing interest in identifying sleep-based biomarkers of cognition and neurodegeneration, including sleep spindles. However, flexibility surrounding spindle definitions and algorithm parameter settings present a methodological challenge. The aim of this study was to characterize how spindle detection parameter settings influence the association between spindle features and cognition and to identify parameters with the strongest association with cognition. METHODS: Adult patients (n = 167, 49 ± 18 years) completed the NIH Toolbox Cognition Battery after undergoing overnight diagnostic polysomnography recordings for suspected sleep disorders. We explored 1000 combinations across seven parameters in Luna, an open-source spindle detector, and used four features of detected spindles (amplitude, density, duration, and peak frequency) to fit linear multiple regression models to predict cognitive scores. RESULTS: Spindle features (amplitude, density, duration, and mean frequency) were associated with the ability to predict raw fluid cognition scores (r = 0.503) and age-adjusted fluid cognition scores (r = 0.315) with the best spindle parameters. Fast spindle features generally showed better performance relative to slow spindle features. Spindle features weakly predicted total cognition and poorly predicted crystallized cognition regardless of parameter settings. CONCLUSIONS: Our exploration of spindle detection parameters identified optimal parameters for studies of fluid cognition and revealed the role of parameter interactions for both slow and fast spindles. Our findings support sleep spindles as a sleep-based biomarker of fluid cognition.

The Neutrophil to Lymphocyte Ratio Is Associated With the Risk of Subsequent Dementia in the Framingham Heart Study.

Objective: Active neutrophils are important contributors to Alzheimer's disease (AD) pathology through the formation of capillary stalls that compromise cerebral blood flow (CBF) and through aberrant neutrophil signaling that advances disease progression. The neutrophil to lymphocyte ratio (NLR) is a proxy of neutrophil-mediated inflammation, and higher NLR is found in persons diagnosed with clinical AD. The objective of this study was to investigate whether increased NLR in older adults is independently associated with the risk of subsequent dementia. Methods: We examined associations of baseline NLR with incident dementia risk in the community-based Framingham Heart Study (FHS) longitudinal cohorts. The association between NLR and risk of dementia was evaluated using the cumulative incidence function (CIF) and inverse probability-weighted Cox proportional cause-specific hazards regression models, with adjustment for age, sex, body mass index (BMI), systolic and diastolic blood pressure, diabetes, current smoking status, low-density lipoprotein (LDH), high-density lipoprotein (LDL), total cholesterol, triglycerides, and history of cardiovascular disease (CVD). Random forest survival models were used to evaluate the relative predictive value of the model covariates on dementia risk. Results: The final study sample included 1,648 participants with FHS (average age, 69 years; 56% women). During follow-up (median, 5.9 years), we observed 51 cases of incident dementia, of which 41 were AD cases. Results from weighted models suggested that the NLR was independently associated with incident dementia, and it was preceded in predictive value only by age, history of CVD, and blood pressure at baseline. Conclusion: Our study shows that individuals with higher NLR are at a greater risk of subsequent dementia during a 5.9-year follow-up period. Further evaluating the role of neutrophil-mediated inflammation in AD progression may be warranted.

Association of Social Support With Brain Volume and Cognition.

Importance: Cognitive resilience refers to the general capacity of cognitive processes to be less susceptible to differences in brain structure from age- and disease-related changes. Studies suggest that supportive social networks reduce Alzheimer disease and related disorder (ADRD) risk by enhancing cognitive resilience, but data on specific social support mechanisms are sparse. Objective: To examine the association of individual forms of social support with a global neuroanatomical measure of early ADRD vulnerability and cognition. Design, Setting, and Participants: This retrospective cross-sectional analysis used prospectively collected data from Framingham Study participants without dementia, stroke, or other neurological conditions who underwent brain magnetic resonance imaging and neuropsychological testing at the same visit. Data from this large, population-based, longitudinal cohort were collected from June 6, 1997, to December 13, 1999 (original cohort), and from September 11, 1998, to October 26, 2001 (offspring cohort). Data were analyzed from May 22, 2017, to June 1, 2021. Exposures: Total cerebral volume and, as a modifying exposure variable, self-reported availability of 5 types of social support measured by the Berkman-Syme Social Network Index. Main Outcomes and Measures: The primary outcome was a global measure of cognitive function. Cognitive resilience was defined as the modification of total cerebral volume's association with cognition, such that smaller ß estimates (presented in SD units) indicate greater cognitive resilience (ie, better cognitive performance than estimated by lower total cerebral volume). Results: The study included 2171 adults (164 in the original cohort and 2007 in the offspring cohort; mean [SD] age, 63 [10] years; 1183 [54%] female). High listener availability was associated with greater cognitive resilience (ß = 0.08, P < .001) compared with low listener availability (ß = 0.20, P = .002). Overall findings persisted after adjustment for potential confounders. Other forms of social support were not significant modifiers (advice: ß = -0.04; P = .40 for interaction; love-affection: ß = -0.07, P = .28 for interaction; emotional support: ß = -0.02, P = .73 for interaction; and sufficient contact: ß = -0.08; P = .11 for interaction). Conclusions and Relevance: The results of this cross-sectional cohort study suggest that social support in the form of supportive listening is associated with greater cognitive resilience, independently modifying the association between lower total cerebral volume and poorer cognitive function that would otherwise indicate increased ADRD vulnerability at the preclinical stage. A refined understanding of social support mechanisms has the potential to inform strategies to reduce ADRD risk and enhance cognitive resilience.

The Long-Term Public Health Impact of Social Distancing on Brain Health: Topical Review.

Social distancing has been a critical public health measure for the COVID-19 pandemic, yet a long history of research strongly suggests that loneliness and social isolation play a major role in several cognitive health issues. What is the true severity and extent of risks involved and what are potential approaches to balance these competing risks? This review aimed to summarize the neurological context of social isolation and loneliness in population health and the long-term effects of social distancing as it relates to neurocognitive aging, health, and Alzheimer's disease and related dementias. The full scope of the underlying causal mechanisms of social isolation and loneliness in humans remains unclear partly because its study is not amenable to randomized controlled trials; however, there are many detailed experimental and observational studies that may provide a hypothesis-generating theoretical framework to better understand the pathophysiology and underlying neurobiology. To address these challenges and inform future studies, we conducted a topical review of extant literature investigating associations of social isolation and loneliness with relevant biological, cognitive, and psychosocial outcomes, and provide recommendations on how to approach the need to fill key knowledge gaps in this important area of research.

Association of Midlife Depressive Symptoms with Regional Amyloid-ß and Tau in the Framingham Heart Study.

BACKGROUND: Depressive symptoms predict increased risk for dementia decades before the emergence of cognitive symptoms. Studies in older adults provide preliminary evidence for an association between depressive symptoms and amyloid-ß (Aß) and tau accumulation. It is unknown if similar alterations are observed in midlife when preventive strategies may be most effective. OBJECTIVE: The study aim was to evaluate the association between depressive symptoms and cerebral Aß and tau in a predominately middle-aged cohort with examination of the apolipoprotein (APOE) ɛ4 allele as a moderator. METHODS: Participants included 201 adults (mean age 53±8 years) who underwent 11C-Pittsburgh Compound B amyloid and 18F-Flortaucipir tau positron emission tomography (PET) imaging. Depressive symptoms were evaluated with the Center for Epidemiological Studies Depression Scale (CES-D) at the time of PET imaging, as well as eight years prior. Associations between depressive symptoms at both timepoints, as well as depression (CES-D≥16), with regional Aß and tau PET retention were evaluated with linear regression adjusting for age and sex. Interactions with the APOE ɛ4 allele were explored. RESULTS: Depressive symptoms and depression were not associated with PET outcomes in the overall sample. However, among APOE ɛ4 allele carriers, there was a significant cross-sectional association between depressive symptoms and increased tau PET uptake in the entorhinal cortex (ß= 0.446, SE = 0.155, p = 0.006) and amygdala (ß= 0.350, SE = 0.133, p = 0.012). CONCLUSION: Although longitudinal studies are necessary, the results suggest that APOE ɛ4 carriers with depressive symptoms may present with higher susceptibility to early tau accumulation in regions integral to affective regulation and memory consolidation.

Herpes Labialis, Chlamydophila pneumoniae, Helicobacter pylori, and Cytomegalovirus Infections and Risk of Dementia: The Framingham Heart Study.

BACKGROUND: An association between chronic infectious diseases and development of dementia has been suspected for decades, based on the finding of pathogens in postmortem brain tissue and on serological evidence. However, questions remain regarding confounders, reverse causality, and how accurate, reproducible and generalizable those findings are. OBJECTIVE: Investigate whether exposure to Herpes simplex (manifested as herpes labialis), Chlamydophila pneumoniae (C. pneumoniae), Helicobacter pylori (H. pylori), and cytomegalovirus (CMV) modifies the risk of dementia in a populational cohort. METHODS: Questionnaires regarding incidence of herpes infections were administered to Original Framingham Study participants (n = 2,632). Serologies for C. pneumoniae, H. pylori, and CMV were obtained in Original (n = 2,351) and Offspring cohort (n = 3,687) participants. Participants are under continuous dementia surveillance. Brain MRI and neuropsychological batteries were administered to Offspring participants from 1999-2005. The association between each infection and incident dementia was tested with Cox models. Linear models were used to investigate associations between MRI or neuropsychological parameters and serologies. RESULTS: There was no association between infection serologies and dementia incidence, total brain volume, and white matter hyperintensities. Herpes labialis was associated with reduced 10-year dementia risk (HR 0.66, CI 0.46-0.97), but not for the duration of follow-up. H. pylori antibodies were associated with worse global cognition (ß -0.14, CI -0.22, -0.05). CONCLUSION: We found no association between measures of chronic infection and incident dementia, except for a reduction in 10-year dementia risk for patients with herpes labialis. This unexpected result requires confirmation and further characterization, concerning antiviral treatment effects and capture of episodes.

PM2.5 associated with gray matter atrophy reflecting increased Alzheimers risk in older women.

OBJECTIVE: To examine whether late-life exposure to PM2.5 (particulate matter with aerodynamic diameters <2.5-µm) contributes to progressive brain atrophy predictive of Alzheimer's disease (AD) using a community-dwelling cohort of women (aged 70-89) with up to two brain MRI scans (MRI-1: 2005-6; MRI-2: 2010-11). METHODS: AD pattern similarity (AD-PS) scores, developed by supervised machine learning and validated with MRI data from the AD Neuroimaging Initiative, was used to capture high-dimensional gray matter atrophy in brain areas vulnerable to AD (e.g., amygdala, hippocampus, parahippocampal gyrus, thalamus, inferior temporal lobe areas and midbrain). Based on participants' addresses and air monitoring data, we implemented a spatiotemporal model to estimate 3-year average exposure to PM2.5 preceding MRI-1. General linear models were used to examine the association between PM2.5 and AD-PS scores (baseline and 5-year standardized change), accounting for potential confounders and white matter lesion volumes. RESULTS: For 1365 women aged 77.9±3.7 years in 2005-6, there was no association between PM2.5 and baseline AD-PS score in cross-sectional analyses (ß=-0.004; 95% CI: -0.019, 0.011). Longitudinally, each interquartile range increase of PM2.5 (2.82-µg/m3) was associated with increased AD-PS scores during the follow-up, equivalent to a 24% (hazard ratio=1.24; 95% CI: 1.14, 1.34) increase in AD risk over 5-years (n=712; aged 77.4±3.5 years). This association remained after adjustment for socio-demographics, intracranial volume, lifestyle, clinical characteristics, and white matter lesions, and was present with levels below US regulatory standards (<12-µg/m3). CONCLUSIONS: Late-life exposure to PM2.5 is associated with increased neuroanatomical risk of AD, which may not be explained by available indicators of cerebrovascular damage.

Particulate matter and episodic memory decline mediated by early neuroanatomic biomarkers of Alzheimer's disease.

Evidence suggests exposure to particulate matter with aerodynamic diameter <2.5 µm (PM2.5) may increase the risk for Alzheimer's disease and related dementias. Whether PM2.5 alters brain structure and accelerates the preclinical neuropsychological processes remains unknown. Early decline of episodic memory is detectable in preclinical Alzheimer's disease. Therefore, we conducted a longitudinal study to examine whether PM2.5 affects the episodic memory decline, and also explored the potential mediating role of increased neuroanatomic risk of Alzheimer's disease associated with exposure. Participants included older females (n = 998; aged 73-87) enrolled in both the Women's Health Initiative Study of Cognitive Aging and the Women's Health Initiative Memory Study of Magnetic Resonance Imaging, with annual (1999-2010) episodic memory assessment by the California Verbal Learning Test, including measures of immediate free recall/new learning (List A Trials 1-3; List B) and delayed free recall (short- and long-delay), and up to two brain scans (MRI-1: 2005-06; MRI-2: 2009-10). Subjects were assigned Alzheimer's disease pattern similarity scores (a brain-MRI measured neuroanatomical risk for Alzheimer's disease), developed by supervised machine learning and validated with data from the Alzheimer's Disease Neuroimaging Initiative. Based on residential histories and environmental data on air monitoring and simulated atmospheric chemistry, we used a spatiotemporal model to estimate 3-year average PM2.5 exposure preceding MRI-1. In multilevel structural equation models, PM2.5 was associated with greater declines in immediate recall and new learning, but no association was found with decline in delayed-recall or composite scores. For each interquartile increment (2.81 µg/m3) of PM2.5, the annual decline rate was significantly accelerated by 19.3% [95% confidence interval (CI) = 1.9% to 36.2%] for Trials 1-3 and 14.8% (4.4% to 24.9%) for List B performance, adjusting for multiple potential confounders. Long-term PM2.5 exposure was associated with increased Alzheimer's disease pattern similarity scores, which accounted for 22.6% (95% CI: 1% to 68.9%) and 10.7% (95% CI: 1.0% to 30.3%) of the total adverse PM2.5 effects on Trials 1-3 and List B, respectively. The observed associations remained after excluding incident cases of dementia and stroke during the follow-up, or further adjusting for small-vessel ischaemic disease volumes. Our findings illustrate the continuum of PM2.5 neurotoxicity that contributes to early decline of immediate free recall/new learning at the preclinical stage, which is mediated by progressive atrophy of grey matter indicative of increased Alzheimer's disease risk, independent of cerebrovascular damage.

Whole blood microRNA expression associated with stroke: Results from the Framingham Heart Study.

Emerging evidence suggests microRNAs (miRNAs) may play an important role in explaining variation in stroke risk and recovery in humans, yet there are still few longitudinal studies examining the association between whole blood miRNAs and stroke. Accounting for multiple testing and adjusting for potentially confounding technical and clinical variables, here we show that whole blood miR-574-3p expression was significantly lower in participants with chronic stroke compared to non-cases. To explore the functional relevance of our findings, we analyzed miRNA-mRNA whole blood co-expression, pathway enrichment, and brain tissue gene expression. Results suggest miR-574-3p is involved in neurometabolic and chronic neuronal injury response pathways, including brain gene expression of DBNDD2 and ELOVL1. These results suggest miR-574-3p plays a role in regulating chronic brain and systemic cellular response to stroke and thus may implicate miR-574-3p as a partial mediator of long-term stroke outcomes.

Design and results of a smartphone-based digital phenotyping study to quantify ALS progression.

OBJECTIVE: The amyotrophic lateral sclerosis (ALS) trial outcome measures are clinic based. Active and passive smartphone data can provide important longitudinal information about ALS progression outside the clinic. METHODS: We used Beiwe, a research platform for smartphone-based digital phenotyping, to collect active (self-report ALSFRS-R surveys and speech recordings) and passive (phone sensors and logs) data from patients with ALS for approximately 24 weeks. In clinics, at baseline and every 3 months, we collected vital capacity, ALSFRS-R, and ALS-CBS at enrollment, week 12, and week 24. We also collected ALSFRS-R by telephone at week 6. RESULTS: Baseline in-clinic ALSFRS-R and smartphone self-report correlation was 0.93 (P < 0.001). ALSFRS-R slopes were equivalent and within-subject standard deviation was smaller for smartphone-based self-report (0.26 vs. 0.56). Use of Beiwe afforded weekly collection of speech samples amenable to a variety of analyses, and we found mean pause time to increase by 0.02 sec per month across the sample. INTERPRETATION: Smartphone-based digital phenotyping in people with ALS is feasible and informative. Self-administered smartphone ALSFRS-R scores correlate highly with clinic-based ALSFRS-R scores, have low variability, and could be used in clinical trials. More research is required to fully analyze speech recordings and passive data, and to identify optimal digital markers for use in future ALS clinical trials.