Age-associated cognitive changes in community dwelling adults

随着人口日益老龄化，认知障碍，包括痴呆症，是一个主要的健康问题。延缓认知能力下降的预防措施至关重要。阿尔茨海默病（AD）是痴呆症最常见的病因，其患病率从60岁以下的<1%增加到85岁以上的bb1040%。我们系统地回顾了一些可改变的因素，如教育、吸烟、饮酒、体育活动、咖啡因、抗氧化剂、同型半胱氨酸（Hcy）、n-3脂肪酸，这些因素与各种认知健康结果（包括AD事件）有关。我们在MEDLINE检索已发表的文献（1990年1月至2012年10月），包括横断面研究和队列研究（样本量约300）。分析比较研究，发现各因素、研究设计和研究水平特征的一致性。选择有关AD事件的研究，我们的荟萃分析估计了合并风险比（RR）、人群归因风险百分比（PAR%）并评估了发表偏倚。247项研究被纳入系统评价。对每个风险因素的一致性分析表明，阳性结果从咖啡因的38.9%到体育锻炼的89%不等。与咖啡因、吸烟和抗氧化剂相关的研究相比，教育也有明显更高的“积极发现”倾向。对31项有AD事件的研究进行荟萃分析，得出低教育程度（RR = 1.99; 95%CI: 1.30-3.04）、高Hcy （RR = 1.93; 95%CI: 1.50-2.49）、当前或曾经吸烟（RR = 1.37; 95%CI: 1.23-1.52）的综合RR，同时表明高运动量和n-3脂肪酸具有保护作用。体力活动（PAR% = 31.9; 95%CI: 22.7-41.2）和吸烟（PAR%-31.0%; 95%CI: 17.9-44.3）的估计PAR%特别高。总体而言，未发现显著的发表偏倚。较高的Hcy水平、较低的受教育程度和较少的体育活动是AD发病的强烈预测因子。

Cognitive impairment, including dementia, is a major health concern with the increasing aging population. Preventive measures to delay cognitive decline are of utmost importance. Alzheimer's disease (AD) is the most frequent cause of dementia, increasing in prevalence from <1% below the age of 60 years to >40% above 85 years of age. We systematically reviewed selected modifiable factors such as education, smoking, alcohol, physical activity, caffeine, antioxidants, homocysteine (Hcy), n-3 fatty acids that were studied in relation to various cognitive health outcomes, including incident AD. We searched MEDLINE for published literature (January 1990 through October 2012), including cross-sectional and cohort studies (sample sizes > 300). Analyses compared study finding consistency across factors, study designs and study-level characteristics. Selecting studies of incident AD, our meta-analysis estimated pooled risk ratios (RR), population attributable risk percent (PAR%) and assessed publication bias. 247 studies were retrieved for systematic review. Consistency analysis for each risk factor suggested positive findings ranging from 38.9% for caffeine to 89% for physical activity. Education also had a significantly higher propensity for "a positive finding" compared to caffeine, smoking and antioxidant-related studies. Meta-analysis of 31 studies with incident AD yielded pooled RR for low education (RR = 1.99; 95%CI: 1.30-3.04), high Hcy (RR = 1.93; 95%CI: 1.50-2.49), and current or ever smoking status (RR = 1.37; 95%CI: 1.23-1.52) while indicating protective effects of higher physical activity and n-3 fatty acids. Estimated PAR% were particularly high for physical activity (PAR% = 31.9; 95%CI: 22.7-41.2) and smoking (PAR%-31.0%; 95%CI: 17.9-44.3). Overall, no significant publication bias was found. Higher Hcy levels, lower educational attainment, and decreased physical activity were particularly strong predictors of incident AD. Among modifiable lifestyle factors, diet may affect cognitive health. Cross-sectional and longitudinal associations may exist between dietary exposures e.g., caffeine (mg/d), alcohol (g/d), and nutrient adequacy and cognitive performance and change over time. Data were drawn from a prospective cohort study (n = 628-1305 persons depending on the cognitive outcome; approximately 2 visits/person). Outcomes included 10 cognitive scores, spanning various domains of cognition. Caffeine and alcohol intakes and a nutrient adequacy score (NAS) were estimated from 7-d food diaries. Among key findings, caffeine intake was associated with better baseline global cognition among participants with a baseline age (Agebase) of &#8805;70y. A higher NAS was associated with better baseline global cognition performance (overall, women, Agebase <70y), better baseline verbal memory (immediate and delayed recall, Agebase &#8805;70y), and slower rate of decline or faster improvement in the attention domain (women). For an Agebase of <70y, alcohol consumption was associated with slower improvement on letter fluency and global cognition over time. Conversely, for an Agebase of &#8805;70 y and among women, alcohol intake was related to better baseline attention and working memory. In sum, patterns of diet and cognition associations indicate stratum-specific associations by sex and baseline age. The general observed trend was that of putative beneficial effects of caffeine intake and nutrient adequacy on domains of global cognition, verbal memory, and attention, and mixed effects of alcohol on domains of letter fluency, attention, and working memory. Growing evidence suggests that self-reported physical activity accounts for variability in cognitive function among older adults, and aerobic intervention may improve cognitive function in this population. However, much less is known about the longitudinal association between direct measures of cardiorespiratory fitness and cognitive function across the life span. We examined the prospective association between symptom-limited maximal oxygen consumption (VO2max) and longitudinal performance on a comprehensive neuropsychological battery. Up to 1,400 participants aged 19-94 years underwent initial VO2max assessment and completed subsequent tests of memory, attention, perceptuomotor speed, language, and executive function, in addition to cognitive screening measures, on up to six occasions (mean, M = 2; standard deviation, SD = 1) for up to 18 years (M = 7, SD = 3). Mixed-effects regression models were adjusted for demographic, biomedical, and behavioral confounders. We found significant longitudinal associations between baseline VO2max and trajectory of performance on multiple measures of verbal and visual memory, as well as on a cognitive screening test (all ps < .05). Individuals with lower VO2max had accelerated trajectories of cognitive decline over time. Baseline cardiorespiratory fitness is related to longitudinal neuropsychological performance, and memory appears to be a particularly vulnerable domain. Evidence that aerobic fitness is associated with accelerated cognitive decline emphasizes the possible importance of behavioral interventions to optimize cognitive aging over time. The literature thus far is equivocal about longitudinal associations between total cholesterol and cognitive decline. We examined prospective nonlinear relations of coincident trajectories of total cholesterol and cognitive function among persons free of stroke, dementia, and other neurological disease. Up to 1,601 participants from prospective cohort study (aged 19-93, 51% male, 75% White) underwent fasting cholesterol measurement and neuropsychological assessment on up to 12 occasions (M = 3.2, SD = 2.1) over up to 19 years (M = 6.4, SD = 5.3) of follow-up. Mixed-effects regression analyses were adjusted for age, sex, race, education, systolic blood pressure, body mass index, cardiovascular disease, lipid-lowering medication use, smoking, alcohol use, and depressive symptoms. Analyses revealed significant longitudinal associations between quadratic total cholesterol and performance on measures of global mental status, verbal learning, executive function, and language (all ps < .05). In general, higher total cholesterol was associated with poorer middle-aged or young-old (60-69 years) cognitive performance, but better old-old (80-89 years) cognitive performance. Linear models also revealed an association between lower total cholesterol and accelerated decline in visual memory performance. Overall, results indicate nonlinear longitudinal relations of total cholesterol to cognitive decline. Evidence that depressive symptoms are inversely related to n-3 (omega-3) fatty acids is growing among United States adults. We assessed whether self-reported depressive symptoms were inversely associated with n-3 fatty acid intakes by using a cross-sectional study in 1746 adults (aged 30-65 y) in Baltimore City, MD (2004-2009). The 20-item Center for Epidemiologic Studies-Depression Scale (CES-D) was used, with a CES-D score &#8805;16 suggestive of elevated depressive symptoms (EDS). N-3 highly unsaturated fatty acids (HUFAs; &#8805;20 carbons), n-3 polyunsaturated fatty acids (PUFAs; >/=18 carbons), and plausible ratios with n-6 (omega6) fatty acids were estimated. EDS prevalence was 18.1% among men and 25.6% among women. In women, the uppermost tertile (tertile 3) of n-3 PUFAs (compared with tertile 1) was associated with reduced odds of EDS by 49%, with a substantial sex differential. The n-3 PUFA:n-6:PUFA ratio was inversely related to EDS among women (tertile 2 vs. tertile 1, OR: 0.74; 95% CI: 0.41, 1.32; tertile 3 vs. tertile 1, OR: 0.47; 95% CI: 0.27, 0.83). A similar pattern was noted for n-3 HUFA:n-6 HUFA among women.