Faculty Bibliography

BACKGROUND AND OBJECTIVE/OBJECTIVE: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:Retrospective analysis of prospectively collected data from the population-based Framingham Study cohorts (09/09/1948-12/31/2018). Eligible participants had loneliness assessed and were dementia-free at baseline. Loneliness was recorded using 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 2308 participants (mean age, 73 [SD, 9] years; 56% women) who met eligibility in the dementia sample, 14% (329/2308) developed dementia; 6% (144/2308) 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 younger than age 80 without APOE ε4 alleles had a three-fold greater risk (adjusted hazard ratio, 3.03; 95% CI, 1.63-5.62). Among 1875 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/CONCLUSIONS: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 based on 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/METHODS:This study provides Class I evidence that loneliness increases the 10-year risk of developing dementia.

Importance/UNASSIGNED: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/UNASSIGNED: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/UNASSIGNED: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/UNASSIGNED: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/UNASSIGNED: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 β estimates (presented in SD units) indicate greater cognitive resilience (ie, better cognitive performance than estimated by lower total cerebral volume). Results/UNASSIGNED: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 (β = 0.08, P < .001) compared with low listener availability (β = 0.20, P = .002). Overall findings persisted after adjustment for potential confounders. Other forms of social support were not significant modifiers (advice: β = -0.04; P = .40 for interaction; love-affection: β = -0.07, P = .28 for interaction; emotional support: β = -0.02, P = .73 for interaction; and sufficient contact: β = -0.08; P = .11 for interaction). Conclusions and Relevance/UNASSIGNED: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.

INTRODUCTION/BACKGROUND:This study investigates whether midlife cortisol levels predict Alzheimer's disease (AD) biomarker burden 15 years later, with particular attention to sex differences and menopausal status. METHODS:F]Flortaucipir) positron emission tomography (PET) imaging conducted 15 years later. We performed multivariable regression analyses adjusted for confounders including, apolipoprotein E4 (APOE4) status. RESULTS:Elevated midlife cortisol correlated with increased amyloid deposition, specifically in post-menopausal women, predominantly in posterior cingulate, precuneus, and frontal-lateral regions (p < 0.05). No significant associations were observed with tau burden or in males. DISCUSSION/CONCLUSIONS:These findings reveal post-menopausal women with high midlife cortisol are at increased risk of AD. Results highlight the importance of identifying early risk factors when biomarkers are detectable but cognitive impairment is absent. HIGHLIGHTS/CONCLUSIONS:High midlife cortisol is linked to increased amyloid deposition in post-menopausal women. Cortisol showed no association with tau pathology. Post-menopausal hormone changes may amplify cortisol's effects on amyloid.

Neurologic conditions are a leading cause of morbidity and mortality within the United States and worldwide. Brain health is a global concern, and the American Academy of Neurology's Brain Health Initiative promises to drive progress in this field over the next decades. Neurologists with detailed training and insight into brain function are uniquely positioned to apply emerging preventive health data to promote healthy brain development and maintain optimal brain function throughout the lifespan. The neurologist's role in promoting brain health is also vital in patients with active neurologic disease, in whom preventive measures may reduce recurrence or slow progression of disease and may enhance quality of life and overall function. In this Emerging Issues in Neurology article, we present the factors that may protect brain function and frame a practical approach to screening assessments and preventive interventions that neurology clinicians may consider to improve the brain health of patients at all life stages.

INTRODUCTION/BACKGROUND:We evaluated whether higher Dietary Inflammatory Index (DII) scores were associated with increased incidence of all-cause dementia and Alzheimer's disease (AD) dementia over 22.3 years of follow-up in the community-based Framingham Heart Study Offspring cohort. METHODS:One thousand four hundred eighty-seven participants (mean ± standard deviation, age in years 69 ± 6) completed food frequency questionnaires (FFQs) and had incident all-cause dementia and AD surveillance data available. RESULTS:Two hundred forty-six participants developed all-cause dementia (including AD, n = 187) over a median follow-up time of 13.1 years. Higher DII scores, averaged across a maximum of three timepoints, were associated with an increased incidence of all-cause dementia and AD after adjustment for demographic, lifestyle, and clinical covariates (hazard ratio [HR] 1.21, 95% confidence interval [CI] 1.10-1.33, P < 0.001; HR 1.20, 95% CI: 1.07-1.34d, P = 0.001, respectively). DISCUSSION/CONCLUSIONS: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 that correlate with low DII scores may prevent late-life dementia. HIGHLIGHTS/CONCLUSIONS:Higher Dietary Inflammatory Index (DII) scores were associated with an increased incidence of all-cause dementia. Higher DII scores were associated with an increased incidence of Alzheimer's disease dementia. Diets that correlate with low DII scores may prevent late-life dementia.

AIM/OBJECTIVE:The current study aims to investigate the association of serum brain-derived neurotrophic factor (BDNF) levels with symptoms of depression in adults with and without prevalent cardiovascular disease (CVD), an often burdensome comorbidity. METHODS:This cross-sectional study included participants from FHS (Framingham Heart Study) who had available serum BDNF levels. Depressive symptoms were assessed using the Center for Epidemiological Studies-Depression Scale (CES-D) with a score ≥16 indicating mild to moderate and ≥21 severe depression. Participants taking antidepressant medications were excluded from the study. RESULTS:Altogether 3716 FHS participants were included in the final analysis (mean age, 64.3 ± 11.5 years; 55% women). After adjusting for potential confounders, greater BDNF levels were associated with reduced severe depression risk (odds ratio [OR], 0.78 [95% CI, 0.64-0.96]; P = 0.016). Among participants with CVD, greater BDNF levels were related to lower risk of depressive symptoms (CES-D ≥ 16 OR, 0.63 [95% CI, 0.45-0.89], P = 0.008; CES-D ≥ 21 OR, 0.49 [95% CI, 0.31-0.76], P = 0.002). The inverse relationship between BDNF and depressive symptom risk was present in women with CVD (CES-D ≥ 16 OR, 0.63 [95% CI, 0.40-0.99], P = 0.047; CES-D ≥ 21 OR, 0.38 [95% CI, 0.21-0.70], P = 0.002) but not in men. CONCLUSION/CONCLUSIONS:Lower serum BDNF levels are associated with a higher risk of depressive symptoms in CVD, particularly among women. These findings implicate BDNF in the complex biological mechanisms that underlie prior associations observed between CVD and depression. To reduce the burden of depression in the large proportion of midlife and older adults with CVD, a better understanding of how BDNF may modify these pathways is merited.

BACKGROUNDS/BACKGROUND:Sleep disturbances are prevalent among elderly individuals. While polysomnography (PSG) serves as the gold standard for sleep monitoring, its extensive setup and data analysis procedures impose significant costs and time constraints, thereby restricting the long-term application within the general public. Our laboratory introduced an innovative biomarker, utilizing artificial intelligence algorithms applied to PSG data to estimate brain age (BA), a metric validated in cohorts with cognitive impairments. Nevertheless, the potential of exercise, which has been a recognized means of enhancing sleep quality in middle-aged and older adults to reduce BA, remains undetermined. METHODS:We conducted an exploratory study to evaluate whether 12 weeks of moderate-intensity exercise can improve cognitive function, sleep quality, and the brain age index (BAI), a biomarker computed from overnight sleep electroencephalogram (EEG), in physically inactive middle-aged and older adults. Home wearable devices were used to monitor heart rate and overnight sleep EEG over this period. The NIH Toolbox Cognition Battery, in-lab overnight polysomnography, cardiopulmonary exercise testing, and a multiplex cytokines assay were employed to compare pre- and post-exercise brain health, exercise capacity, and plasma proteins. RESULTS:In total, 26 participants completed the initial assessment and exercise program, and 24 completed all procedures. Data are presented as mean [lower 95% CI of mean, upper 95% CI of mean]. Participants significantly increased maximal oxygen consumption (Pre: 21.11 [18.98, 23.23], Post 22.39 [20.09, 24.68], mL/kg/min; effect size: -0.33) and decreased resting heart rate (Pre: 66.66 [63.62, 67.38], Post: 65.13 [64.25, 66.93], bpm; effect size: -0.02) and sleeping heart rate (Pre: 64.55 [61.87, 667.23], Post: 62.93 [60.78, 65.09], bpm; effect size: -0.15). Total cognitive performance (Pre: 111.1 [107.6, 114.6], Post: 115.2 [111.9, 118.5]; effect size: 0.49) was significantly improved. No significant differences were seen in BAI or measures of sleep macro- and micro-architecture. Plasma IL-4 (Pre: 0.24 [0.18, 0.3], Post: 0.33 [0.24, 0.42], pg/mL; effect size: 0.49) was elevated, while IL-8 (Pre: 5.5 [4.45, 6.55], Post: 4.3 [3.66, 5], pg/mL; effect size: -0.57) was reduced. CONCLUSIONS:max) and plasma cytokine profiles. However, we found no measurable effects on sleep architecture or BAI. It remains to be seen whether a study with a larger sample size and more intensive or more prolonged exercise exposure can demonstrate a beneficial effect on sleep quality and brain age.

BACKGROUND/UNASSIGNED:Loneliness has been declared an "epidemic" associated with negative physical, mental, and cognitive health outcomes such as increased dementia risk. Less is known about the relationship between loneliness and advanced neuroimaging correlates of Alzheimer's disease (AD). OBJECTIVE/UNASSIGNED:To assess whether loneliness was associated with advanced neuroimaging markers of AD using neuroimaging data from Framingham Heart Study (FHS) participants without dementia. METHODS/UNASSIGNED:In this cross-sectional observational analysis, we used functional connectivity MRI (fcMRI), amyloid-β (Aβ) PET, and tau PET imaging data collected between 2016 and 2019 on eligible FHS cohort participants. Loneliness was defined as feeling lonely at least one day in the past week. The primary fcMRI marker was Default Mode Network intra-network connectivity. The primary PET imaging markers were Aβ deposition in precuneal and FLR (frontal, lateral parietal and lateral temporal, retrosplenial) regions, and tau deposition in the amygdala, entorhinal, and rhinal regions. RESULTS/UNASSIGNED:Of 381 participants (mean age 58 [SD 10]) who met inclusion criteria for fcMRI analysis, 5% were classified as lonely (17/381). No association was observed between loneliness status and network changes. Of 424 participants (mean age 58 [SD = 10]) meeting inclusion criteria for PET analyses, 5% (21/424) were lonely; no associations were observed between loneliness and either Aβ or tau deposition in primary regions of interest. CONCLUSIONS/UNASSIGNED:In this cross-sectional study, there were no observable associations between loneliness and select fcMRI, Aβ PET, and tau PET neuroimaging markers of AD risk. These findings merit further investigation in prospective studies of community-based cohorts.

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.