Elsevier

Nutrition

Volume 32, Issue 6, June 2016, Pages 628-636
Nutrition

Meta-analysis
Habitual coffee consumption and risk of cognitive decline/dementia: A systematic review and meta-analysis of prospective cohort studies

https://doi.org/10.1016/j.nut.2015.11.015Get rights and content

Highlights

  • We conducted a meta-analysis including 11 prospective studies.

  • Dose–response analysis was used to investigate the influence of coffee on dementia.

  • Higher dietary coffee consumption is associated with reduced risk for Alzheimer disease.

Abstract

Objective

Findings from epidemiologic studies of coffee consumption and risk for cognitive decline or dementia are inconclusive. The aim of this study was to conduct a meta-analysis of prospective studies to assess the association between coffee consumption and the risk for cognitive decline and dementia.

Methods

Relevant studies were identified by searching PubMed and Embase databases between 1966 and December 2014. Prospective cohorts that reported relative risk (RRs) and 95% confidence intervals (CIs) for the association of coffee consumption with dementia incidence or cognitive changing were eligible. Study-specific RRs were combined by using a random-effects model.

Results

Eleven prospective studies, including 29,155 participants, were included in the meta-analysis. The combined RR indicated that high coffee consumption was not associated with the different measures of cognitive decline or dementia (summary RR, 0.97; 95% CI, 0.84–1.11). Subgroup analyses suggested a significant inverse association between highest coffee consumption and the risk for Alzheimer disease (summary RR, 0.73; 95% CI, 0.55–0.97). The dose–response analysis, including eight studies, did not show an association between the increment of coffee intake and cognitive decline or dementia risk (an increment of 1 cup/d of coffee consumed; summary RR, 1.00; 95% CI, 0.98–1.02).

Conclusions

The present study suggests that higher coffee consumption is associated with reduced risk for Alzheimer disease. Further randomized controlled trials or well-designed cohort studies are needed to determine the association between coffee consumption and cognitive decline or dementia.

Introduction

Evidence from experimental studies of in vitro and preclinical animal models indicates that caffeine and other bioactive components of coffee may have plausible neuroprotective mechanisms on cognitive decline and dementia [1]. However, results from observational prospective studies, randomized controlled trials, and epidemiology of coffee consumption and cognitive decline or dementia risk were inconclusive. Some studies suggest a protective association, whereas others report no benefit. A systematic review and meta-analysis demonstrated a trend toward a protective effect of caffeine (including coffee) in cognitive decline or dementia [2]. In contrast, a recent meta-analysis of 247 cross-sectional and cohort studies of modifiable factors associated with cognition and dementia did not find an association between coffee intake and cognitive change [3]. To examine whether the association between coffee consumption and risk for cognitive decline or dementia varies by levels of coffee intake, a meta-analysis of prospective studies was performed. Whether the association varied by follow-up duration also was assessed because some studies indicated that the coffee protective association is observed only in the short term [4]. Additionally, whether the relation differed by dementia type, sex, and region of participation was examined.

Section snippets

Literature search and selection

Standard criteria were followed for performing and reporting meta-analyses of observational studies. A literature search was performed using PubMed and Embase databases that included the years 1966 through December 2014. We used the search terms coffee or caffeine combined with dementia or Alzheimer disease or cognitive decline or cognitive impairment. The search was limited to studies carried out in humans. Additionally, the coffee and dementia or Alzheimer disease of medical subject headings

Study characteristics

The literature search identified 127 articles, of which 116 were excluded after review of the title or abstract (Fig. 1). The remaining 11 articles [4], [13], [14], [15], [16], [17], [18], [19], [20], [21], [22] were based on data from prospective studies and were eligible for inclusion in the meta-analysis. The studies were published from 2001 through 2014 (Table 1). Combined, these studies had 29,155 study participants. Nine studies were conducted in Europe and two in Asia. The studies

Discussion

Findings from this meta-analysis of prospective studies indicated that dietary coffee consumption may not be associated with the different measures of cognitive decline or dementia. The result of dose–response analysis also did not show an association between the increment of coffee intake and different measures of cognitive decline or dementia. However, in the subgroup analysis, a statistically significant 27% reduction in risk for AD was observed in the highest category of coffee consumption

Conclusion

The present meta-analysis of prospective cohorts suggests that higher coffee consumption is associated with reduced risk for AD. Randomized controlled trials or well-designed cohort studies are needed to determine the association between coffee and cognitive decline or dementia.

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  • Cited by (0)

    This study was supported by the National Natural Science Foundation of China (No. 81171085, 81230026, and 81300988), the Natural Science Foundation of Jiangsu Province of China (BL2012013), and the Medical Leading Talent and Innovation Team Project of Jiangsu Province (LJ201101). Q-PL and Y-FW contributed equally to this study and reviewed articles and extracted information. YX, Q-PL, and Y-FW conceived the idea and designed the study. Y-FW and Z-MW undertook the statistical analysis. Y-FW, H-YC, and TX wrote the first draft of the manuscript. HD and HW edited the English. All of the authors helped interpret the results and write and revise the manuscript. The authors acknowledge Brad Peterson for editing the English. The authors have no conflicts of interest to declare.

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