Dietary Fat Intake and Risk of Alzheimer's Disease and Dementia: A Meta-Analysis of Cohort Studies

Background: Epidemiological studies showed that dietary fat intake is associated with Alzheimer's disease (AD) and dementia risk, however, the association remain inconsistent. This metaanalysis aimed to systematically examine the association of dietary fat intake with AD and dementia risk. Methods: We have systematically searched PubMed, Embase and the Cochrane Library up to May 1st 2017. Prospective cohort studies were included if they reported on the association of dietary fat intake with AD and dementia risk. Multivariate-adjusted relative risks (RRs) for the highest versus lowest category were pooled by using a random-effects model. Results: A total of 8630 participants and 633 cases from four independent prospective cohort studies were included in the present meta-analysis. A higher dietary saturated fat intake was significantly associated with an increased risk of 39% and 105% for AD (RR: 1.39; 95% CI: 1.00, 1.94) and dementia (RR: 2.05; 95% CI: 1.06, 3.98), respectively. Dose-response analysis indicated a 4 g/day increment of saturated fat intake was related to 15% higher risk of AD (RR: 1.15; 95% CI: 1.01, 1.31). However, there was no significant association found between dietary intake of total, monounsaturated, polyunsaturated fat and AD or dementia risk. Conclusions: This meta-analysis provides significant evidence of positive association between higher saturated fat intake and AD and dementia risk.