Coffee intake and the incident risk of cognitive disorders: A dose-response meta-analysis of nine prospective cohort studies.
Previous epidemiological studies have provided inconsistent conclusions on the impact of coffee consumption in the developing of cognitive disorders. However, no previous meta-analysis has pooled the evidence from the prospective cohort studies to assess the influence of coffee drinking and its potential dose-response patterns on the risk of developing cognitive disorders specifically.



Two databases (PubMed and Embase) were searched for evidence of cohort studies from inception to February 2016. We used a generic inverse-variance method with a random-effects model to pool the fully adjusted relative risks (RRs) and the corresponding 95% confidence intervals (CIs). In the dose-response analyses, a generalized least-squares trend estimation model was applied to computing the study-specific slopes.



Nine prospective cohort studies involving 34,282 participants were included in our study. The duration of follow-up years ranged from 1.3 to 28. Compared with <1 cup, daily drinking of 1-2 cups of coffee was inversely linked with the occurrence of cognitive disorders (i.e., Alzheimer's disease, dementia, cognitive decline, and cognitive impairment), and the pooled RR (95% CI) was 0.82 (0.71, 0.94) with evidence of non-significant heterogeneity (I2= 25%). Non-significant differences were presented for the association between coffee consumption (>3 vs. <1 cup/d) and incident cognitive disorders. The dose-response analysis showed a "J-shaped" curve relationship of the risk of developing cognitive disorders with coffee consumption.



A "J-shaped" association was presented between coffee intake and incident cognitive disorders, with the lowest risk of incident cognitive disorders at a daily consumption level of 1-2 cups of coffee.
Department of Epidemiology, Institute of Geriatrics, Chinese PLA (People's Liberation Army) General Hospital, China; Beijing Key Laboratory of Aging and Geriatrics, Chinese PLA General Hospital, China.
Lei
L
Wu
Department of Nanomedicine, Houston Methodist Research Institute, Houston, USA.
Dali
D
Sun
Department of Epidemiology, Institute of Geriatrics, Chinese PLA (People's Liberation Army) General Hospital, China; Beijing Key Laboratory of Aging and Geriatrics, Chinese PLA General Hospital, China; State Key Laboratory of Kidney Disease, Chinese PLA General Hospital, China. Electronic address: yhe301@x263.net.
Yao
Y
He
D003069:Coffee; D003072:Cognition Disorders / Q000453:epidemiology* / Q000517:prevention & control*; D003704:Dementia / Q000453:epidemiology / Q000517:prevention & control; D004032:Diet; D006801:Humans; D015994:Incidence; D012307:Risk Factors
D003069:Coffee
Alzheimer's disease; Coffee intake; Cognitive disorders; Cognitive impairment; Dementia; Meta-analysis