Caffeine Intake from Coffee or Tea and Cognitive Disorders: A Meta-Analysis of Observational Studies

Abstract

Background: Observational epidemiological studies such as cross-sectional, case-control, and cohort studies have reported inconsistent findings regarding the association between caffeine intake from coffee or tea and the risk of cognitive disorders such as dementia, Alzheimer's disease, cognitive impairment, and cognitive decline. Methods: We searched PubMed and EMBASE in September 2014. Three evaluators independently extracted and reviewed articles, based on predetermined selection criteria. Results: Out of 293 articles identified through the search and bibliographies of relevant articles, 20 epidemiological studies from 19 articles, which involved 31,479 participants (8,398 in six cross-sectional studies, 4,601 in five case-control studies, and 19,918 in nine cohort studies), were included in the final analysis. The pooled odds ratio (OR) or relative risk (RR) of caffeine intake from coffee or tea for cognitive disorders (dementia, Alzheimer's disease, cognitive impairment, and cognitive decline) was 0.82 (95% confidence interval [CI], 0.67-1.01, I² = 63.2%) in a random-effects meta-analysis. In the subgroup meta-analysis by caffeine sources, the summary OR or RR of coffee intake was 0.83 (95% CI, 0.70-0.98; I² = 44.8%). However, in the subgroup meta-analysis by study design, the summary estimates (RR or OR) of coffee intake for cognitive disorders were 0.70 (95% CI, 0.50-0.98; I² = 42.0%) for cross-sectional studies, 0.82 (95% CI, 0.55-1.24; I² = 33.4%) for case-control studies, and 0.90 (95% CI, 0.59-1.36; I² = 60.0%) for cohort studies. Conclusions: This meta-analysis found that caffeine intake from coffee or tea was not associated with the risk of cognitive disorders.

Meta-Analysis of the Association between Tea Intake and the Risk of Cognitive Disorders

“…Subgroup analyses showed similar results in subgroups. Our results were the opposite of a recent meta-analysis which found no association between caffeine from coffee or tea and cognitive disorders [13]. Caffeine is an important component in tea and coffee.…”

“…However, these analyses only examined the effect of one major component in tea such as caffeine [13] or flavonoids [14], and some other caffeine contained food or drinks like coffee were also considered in these analyses.…”

Effect of Caffeine Intake on Retinal Microsurgical Performance

“…Caffeine is a xanthine derivative present in tea (black/green), coffee (mostly depends of variety of brewed coffee and tea) and, to a lesser extent, chocolate [2,13]. Caffeine consumption enhances alertness and concentration, which could be useful for a microsurgeons embarking on a lengthy procedure.…”

“…It mainly acts upon the central nervous system, with widely known physiological and psychological effects (increased alertness, enhanced vigilance, reduced fatigue) [1][2][3][4][5][6]. All its effects are through the antagonism of the A1 and A2 subtypes of the adenosine receptor, potentiating the effects of sympathetic nervous system stimulation [6].…”

Plant alkaloids as drug leads for Alzheimer's disease

“…A C C E P T E D ACCEPTED MANUSCRIPT 21 intake and the risk of cognitive disorders (Kim et al, 2015). Therefore, additional studies with longer follow-up periods are required to clarify the relationship between caffeine and AD.…”