Greater Risk Of Cognitive Decline Research Articles

Cognitive decline and dementia in diabetes—systematic overview of prospective observational studies

We systematically reviewed and summarised prospective data relating diabetes status to changes in cognitive function over time. Published reports of longitudinal studies that described assessment of cognitive function in people with diabetes were sought. Studies were included if they assessed cognitive function in participants with diabetes at the beginning and at follow-up. Studies were excluded if they had (1) a follow-up period of less than 1 year, (2) a rate of loss to follow-up in excess of 30%, or (3) described selected subgroups. Change in cognitive function was recorded as either the mean change in score and/or the proportion of individuals developing various degrees of change in cognitive function. A pooled estimate was calculated for the latter. Of 1,165 abstracts and titles initially identified, 25 articles met the inclusion and exclusion criteria. Individuals with diabetes had a 1.2- to 1.5-fold greater change over time in measures of cognitive function than those without diabetes. When assessed by the Mini-Mental State Exam and the Digit Symbol Span tests, a diagnosis of diabetes increased the odds of cognitive decline 1.2-fold (95% CI 1.05-1.4) and 1.7-fold (95% CI 1.3-2.3), respectively . The odds of future dementia increased 1.6-fold (95% CI 1.4-1.8). Compared to people without diabetes, people with diabetes have a greater rate of decline in cognitive function and a greater risk of cognitive decline. Cognitive dysfunction should therefore be added to the list of chronic complications of diabetes.

Cognitive Function After Carotid Endarterectomy: Greater Risk of Decline in Symptomatic Patients With Left Internal Carotid Artery Disease

The risk of cognitive decline in patients undergoing carotid endarterectomy (CE) for left internal carotid artery (ICA) (LICA) disease before or after the occurrence of ischemic symptoms has not been fully elucidated. We evaluated whether patients undergoing CE for symptomatic LICA stenosis have greater risk of cognitive decline than patients with asymptomatic LICA disease or right ICA disease. In a series of patients aged 65 years and older, consecutively undergoing CE and free from cognitive impairment, cognitive function was evaluated through the age- and education-adjusted Mini Mental State Examination and the Clock Drawing Task at baseline and at the end of the study period (average follow-up: 44.4 +/- 14.3 months). The analysis included 103 patients (mean age 72.6 +/- 7.0 years; 73 men), of whom 50 had LICA disease (29 symptomatic). At the end of the study period, Mini Mental State Examination score was reduced in patients with symptomatic LICA disease (P < .001) but not in other patients, whereas the Clock Drawing Task score was reduced in both patients with LICA and right ICA. Patients with symptomatic LICA disease had greater risk of cognitive decline than other individuals, either measured by the Mini Mental State Examination score (F = 5.18, P = .002) or by the Clock Drawing Task score (F = 9.42, P = .001). Patients undergoing CE for symptomatic LICA disease appear to be at increased risk of cognitive decline than other individuals. Further studies are needed to confirm these findings and to evaluate whether LICA endarterectomy before occurrence of cerebrovascular ischemic symptoms may provide additive benefit in the prevention of cognitive decline.

Cognitive decline and fatty acid composition of erythrocyte membranes—The EVA Study

Dietary factors might modify cognitive decline that results from aging. Fatty acids, which are limiting factors in brain development, are prime candidates. We studied the relation between erythrocyte membrane fatty acid composition and cognitive decline in free-living volunteers. In 1995, erythrocyte membrane fatty acid composition was measured in 246 men and women (aged 63-74 y) from the Etude du Vieillissement Artériel (EVA) cohort. During a 4-y follow-up, cognitive abilities were assessed longitudinally with the Mini-Mental State Examination. Moderate cognitive decline was defined as a > or = 2-point decrease over the 4 y. The predictive value of fatty acid proportions on cognitive decline was assessed with a multivariate logistic model that included age, sex, education level, and initial Mini-Mental State Examination score as covariates. Higher proportions of both stearic acid (saturated, 18:0) and total n-6 polyunsaturated fatty acids were associated with greater risk of cognitive decline; the odds ratios were 1.91 (95% CI: 1.16, 3.15) and 1.59 (95% CI: 1.04, 2.44), respectively, for 1-SD differences in fatty acid proportions. Conversely, a higher proportion of total n-3 fatty acids was associated with a lower risk of cognitive decline; the odds ratio was 0.59 (95% CI: 0.38, 0.93). The inverse association between cognitive decline and the ratio of n-3 to n-6 fatty acids in erythrocyte membranes agrees with results obtained in some studies that assessed fatty acid intake by using dietary questionnaires. These results require confirmation but provide new rationale for studying how these modifiable risk factors might be implicated in the cognitive aging process.

Blood pressure and cognitive decline in healthy old people.

Both hypertension and cognitive decline are common in old age. We sought to examine the effects of blood pressure (BP) on rates of cognitive decline in a longitudinal study of community-resident healthy old people. A total of 603 initially healthy old people aged over 69 years were visited at home. Subject's age, years of full-time education, Social Occupational Classification, health status and medication use were recorded. Sitting systolic and diastolic BP was measured, and the Mini-Mental State Examination (MMSE) and National Adult Reading Test (NART) administered. Follow-up was planned after 4 years: 69 subjects were dead, 15 were too unwell and 12 had moved away; 78 subjects either refused or failed to reply. Psychometric tests were administered to the remaining 429 (71.1%) after a median period of 4.20 years. Forty-two subjects had significant sensory impairment or interrupted testing. No significant differences in cognitive decline were found between those who had started medication (n = 163) and those remaining untreated (n = 224). Mean MMSE score change was 0.44 points (s.d. 2.07, P < 0.001). Entering all baseline variables into a stepwise regression analysis significant positive effects were found for initial MMSE score (beta = 0.50, P < 0.001), age (beta = 0.17, P < 0.001), systolic BP (beta = 0.16, P < 0.001) and period between testing (beta = 0.14, P = 0.004), and negative effect for NART-predicted IQ (beta = -0.16, P = 0.003).). We conclude that (1) older people exhibit faster age-associated cognitive decline as measured by MMSE; (2) people with higher NART-predicted IQs are relatively protected; (3) people with high systolic BPs are at greater risk of cognitive decline.