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Background: Sedentary behavior is associated with cognitive impairment, but the neuropathological mechanisms underlying their associations are poorly understood. Objective: To investigate the associations of accelerometer-measured sedentary behavior patterns with brain structure and cognition, and further to explore the potential mechanisms. Methods: This community-based study included 2,019 older adults (age≥60 years, 59% women) without dementia derived from participants in the baseline examination of MIND-China (2018-2020). We assessed sedentary parameters using an accelerometer and cognitive function using a neuropsychological test battery. Structural brain markers were assessed on the structural brain MRI scans in a subsample (n = 1,009). Data were analyzed using the general linear, isotemporal substitution, and mediation models. Results: In the total sample (n = 2,019), adjusting for multiple covariates and moderate-to-vigorous-intensity physical activity, longer mean sedentary bout duration was linearly related with lower z-scores of global cognition, verbal fluency, and memory (ptrend < 0.05), whereas greater total sedentary time was linearly associated with lower z-scores of global cognition, verbal fluency, and memory only among individuals with long sedentary time (>10 h/day) (ptrend < 0.05); Breaking up sedentary time with same amount of light-intensity physical activity was significantly associated with higher verbal fluency and memory z-scores (p < 0.05). In the MRI subsample (n = 1,009), separately entering structural brain MRI markers into the mediation models substantially attenuated the associations of mean sedentary bout duration with global cognition, verbal fluency, and memory z-scores. Conclusion: Prolonged uninterrupted sedentary time is associated with poor global cognition, memory, and verbal fluency among rural older adults, and structural brain markers could partially mediate the association.

Deterioration of brain structure and cognitive function occurs as individuals reach advanced age. The former can be observed through various markers of cerebral small vessel disease on magnetic resonance imaging (MRI) scans and the later can be assessed by neuropsychological tests and clinical examinations. In addition, maintaining a favorable cardiovascular health (CVH) status may contribute to delaying brain aging. Having a higher cognitive reserve (CR) capacity may contribute to preserving cognitive function even in the presence of brain damage. In this thesis, we aimed to examine the progression and interrelationships of MRI markers of structural brain aging and the association between the progression of these markers and cognitive decline. Furthermore, we aimed to investigate whether maintaining a favorable CVH status would be related to a slower deterioration of brain structure and whether having a higher CR capacity would be associated with a lower risk of cognitive deterioration and death. Data were derived from the population-based Swedish National study on Aging and Care in Kungsholmen from 2001–2004 to 2016–2019 and the MRI sub-study from 2001–2003 to 2007–2010. Study I: This six-year follow-up study showed that the progression rate of cerebral small vessel disease markers including expansion rates of white matter hyperintensities (WMHs) and lateral ventricles, incidence of lacunes, and shrinkage rate of gray matter volume, but not the progression rate of perivascular spaces (PVSs), steadily increased with aging (P < 0.05). The progression rate of regional WMHs was faster in males than in females and in people without a university degree than those with a degree (P < 0.05). In addition, a higher load of microvascular lesions (i.e., WMHs, PVSs, and lacunes) at baseline was related to faster progression of both microvascular lesions (WMHs and lacunes) and gray matter atrophy (P < 0.05). Study II: This follow-up study showed that a greater burden of WMHs at

Introduction: Early-life educational attainment contributes to cognitive reserve (CR). We investigated the associations of lifelong CR with dementia and mild cognitive impairment (MCI) among older people with limited formal education. Methods: This population-based cohort study included 2,127 dementia-free participants (≥60 years; 59.4% women; 81.5% with no or elementary school) who were examined at baseline (August-December 2014) and follow-up (March-September 2018). Lifelong CR score at baseline was generated from six lifespan intellectual factors. Dementia, MCI, and their subtypes were defined according to the international criteria. Data were analyzed using Cox proportional-hazards models. Results: During the total of 8,330.6 person-years of follow-up, 101 persons were diagnosed with dementia, including 74 with Alzheimer's disease (AD) and 26 with vascular dementia (VaD). The high (vs. low) tertile of lifelong CR score was associated with multivariable-adjusted hazards ratios (95% confidence interval) of 0.28 (0.14–0.55) for dementia and 0.18 (0.07–0.48) for AD. The association between higher CR and reduced AD risk was significant in people aged 60–74 but not in those aged ≥75 years (p for interaction = 0.011). Similarly, among MCI-free people at baseline (n = 1,635), the high (vs. low) tertile of lifelong CR score was associated with multivariable-adjusted hazard ratios of 0.51 (0.38–0.69) for MCI and 0.46 (0.33–0.64) for amnestic MCI. Lifelong CR was not related to VaD or non-amnestic MCI. Discussion: High lifelong CR is associated with reduced risks of dementia and MCI, especially AD and amnestic MCI. It highlights the importance of lifelong CR in maintaining late-life cognitive health even among people with no or limited education.

Introduction: Multidomain intervention approaches have emerged as a potential strategy to reduce dementia risk. We sought to describe the baseline assessment approaches, health conditions, and risk profiles for brain aging of participants in the randomized controlled Multimodal INterventions to delay Dementia and disability in rural China (MIND-China). Methods: MIND-China engaged residents who were >= 60 years of age and living in rural communities in the western Shandong province. In March to September 2018, all participants underwent the core module assessments via face-to-face interviews, clinical examinations, neuropsychological testings, and laboratory tests. Specific modules of examination were performed for sub-samples, including brain magnetic resonance imaging scans, genetic and blood biochemical markers, actigraphy testing, cardiopulmonary coupling analysis for sleep quality and disturbances, audiometric testing, and optical coherence tomography examination. We performed descriptive analysis. Results: In total, 5765 participants (74.9% of all eligible residents) undertook the baseline assessments. The mean age was 70.9 years (standard deviation, 5.9), 57.2% were women, 40.6% were illiterate, and 88.3% were farmers. The overall prevalence of common chronic diseases was 67.2% for hypertension, 23.4% for dyslipidemia, 23.5% for heart disease, 14.4% for diabetes mellitus, and 5.4% for dementia. The prevalence rates of hypertension, diabetes mellitus, dyslipidemia, obesity, heart disease, depressive symptoms, and dementia were higher in women than in men (P < .05). Overall, 87.1% of the participants had at least two of the 15 chronic diseases (89.3% in women vs 84.2% in men, P < .001). Participants examined for the specific modules were younger, more likely to be women, and more educated than those not examined. Discussion: Comprehensive baseline assessments of participants in MIND-China provide extremely valuable data sources for interdisciplinary res