Background and Purpose—This scientific statement provides an overview of the evidence on vascular contributions to cognitive impairment and dementia. Vascular contributions to cognitive impairment ...

Vascular Contributions to Cognitive Impairment and Dementia A Statement for Healthcare Professionals From the American Heart Association/American Stroke Association

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 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. In total, 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/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%=31.09%; 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. Further studies are needed to support other potential modifiable protective factors, such as caffeine.

https://link.springer.com/content/pdf/10.1186%2F1471-2458-14-643.pdf

Epidemiologic studies of modifiable factors associated with cognition and dementia: systematic review and meta-analysis

Background Docosahexaenoic acid (DHA) plays an important role in neural function Decreases in plasma DHA are associated with cognitive decline in healthy elderly adults and in patients with Alzheimer's disease Higher DHA intake is inversely correlated with relative risk of Alzheimer's disease The potential benefits of DHA supplementation in age-related cognitive decline (ARCD) have not been fully examined Objective Determine effects of DHA administration on improving cognitive functions in healthy older adults with ARCD Methods Randomized, double-blind, placebo-controlled, clinical study was conducted at 19 US clinical sites A total of 485 healthy subjects, aged ≥55 with Mini-Mental State Examination >26 and a Logical Memory (Wechsler Memory Scale III) baseline score ≥1 standard deviation below younger adults, were randomly assigned to 900 mg/d of DHA orally or matching placebo for 24 weeks The primary outcome was the CANTAB Paired Associate Learning (PAL), a visuospatial learning and episodic memory test Results Intention-to-treat analysis demonstrated significantly fewer PAL six pattern errors with DHA versus placebo at 24 weeks (difference score, −163 ± 076 [−31, −014, 95% CI], P = 03) DHA supplementation was also associated with improved immediate and delayed Verbal Recognition Memory scores ( P P Conclusions Twenty-four week supplementation with 900 mg/d DHA improved learning and memory function in ARCD and is a beneficial supplement that supports cognitive health with aging Trial Registration Clinicaltrialsgov, Identifier: NCT0027813

Beneficial effects of docosahexaenoic acid on cognition in age-related cognitive decline

While dementia affects 6-10% of persons 65 years or older, industrialized countries have witnessed an alarming rise in obesity. However, obesity's influence on dementia remains poorly understood. The conducted a systematic review and meta-analysis. PUBMED search (1995-2007) resulted in 10 relevant prospective cohort studies of older adults (40-80 years at baseline) with end points being dementia and predictors including adiposity measures, such as body mass index (BMI) and waist circumference (WC). There was a significant U-shaped association between BMI and dementia (P= 0.034), with dementia risk increased for obesity and underweight. Pooled odds ratios (OR) and 95% confidence intervals (CI) for underweight, overweight and obesity compared with normal weight in relation to incident dementia were: 1.36 (1.07, 1.73), 0.88 (0.60, 1.27) and 1.42 (0.93, 2.18) respectively. Pooled ORs and 95% CI for obesity and incident Alzheimer's disease (AD) and vascular dementia were 1.80 (1.00, 3.29) vs. 1.73 (0.47, 6.31) and were stronger in studies with long follow-up (>10 years) and young baseline age (<60 years). Weight gain and high WC or skin-fold thickness increased risks of dementia in all included studies. The meta-analysis shows a moderate association between obesity and the risks for dementia and AD. Future studies are needed to understand optimal weight and biological mechanisms

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Obesity and central obesity as risk factors for incident dementia and its subtypes: a systematic review and meta‐analysis

It is the position of the American Dietetic Association (ADA) and Dietitians of Canada (DC) that dietary fat for the adult population should provide 20% to 35% of energy and emphasize a reduction in saturated fatty acids and trans-fatty acids and an increase in n-3 polyunsaturated fatty acids. ADA and DC recommend a food-based approach for achieving these fatty acid recommendations; that is, a dietary pattern high in fruits and vegetables, whole grains, legumes, nuts and seeds, lean protein (ie, lean meats, poultry, and low-fat dairy products), fish (especially fatty fish high in n-3 fatty acids), and use of nonhydrogenated margarines and oils. Implicit to these recommendations for dietary fatty acids is that unsaturated fatty acids are the predominant fat source in the diet. These fatty acid recommendations are made in the context of a diet consistent with energy needs (ie, to promote a healthful body weight). ADA and DC recognize that scientific knowledge about the effects of dietary fats on human health is incomplete and take a prudent approach in recommending a reduction in those fatty acids that increase risk of disease, while promoting intake of those fatty acids that benefit health. Registered dietitians play a pivotal role in translating dietary recommendations for fat and fatty acids into healthful dietary patterns for different population groups.

Position of the American Dietetic Association and Dietitians of Canada: dietary fatty acids.

Plasma n−3 fatty acids and the risk of cognitive decline in older adults: the Atherosclerosis Risk in Communities Study

The impact of socio-economic factors on functional status decline among community-dwelling older adults in China

Background: Plasma fatty acids may affect the risk of cognitive decline in older adults. Objectives: We prospectively studied the association between plasma fatty acids and cognitive decline in adults aged 50–65 y at baseline and conducted a subgroup analysis. Design: From 1987 through 1989, the Atherosclerosis Risk in Communities(ARIC)Studyanalyzedplasmafattyacidsincholesterylesters and phospholipids in whites residing in Minneapolis, MN. From 1990 through 1992 and from 1996 through 1998, 3 neuropsychological tests in the domains of delayed word recall, psychomotor speed, and verbal fluencywereadministered.Weselectedcutoffsforstatisticallyreliable cognitive decline in each of these domains and a measure of global cognitive change computed by principal-components analysis. Multivariate logistic regression was conducted. Focusing on n3 highly unsaturated fatty acids (HUFAs), a subgroup analysis assessed differential association across potential effect modifiers implicated in oxidative stress and increased risk of neurodegenerative disease. Results: In the 2251 study subjects, the risk of global cognitive decline increased with elevated palmitic acid in both fractions and withhigharachidonicacidandlowlinoleicacidincholesterylesters. Higher n3 HUFAs reduced the risk of decline in verbal fluency, particularly in hypertensive and dyslipidemic subjects. No significant findings were shown for psychomotor speed or delayed word recall. Conclusions: Promoting higher intakes of n3 HUFAs in the diet of hypertensiveanddyslipidemicpersonsmayhavesubstantialbenefitsin reducing their risk of cognitive decline in the area of verbal fluency. However, clinical trials are needed to confirm this finding. Am J Clin Nutr 2007;85:1103–11.

May A Beydoun

Papers

Plasma n−3 fatty acids and the risk of cognitive decline in older adults: the Atherosclerosis Risk in Communities Study

The impact of socio-economic factors on functional status decline among community-dwelling older adults in China

Plasma n3 fatty acids and the risk of cognitive decline in older adults: the Atherosclerosis Risk in Communities Study 1-3