Impact of coffee-derived chlorogenic acid on cognition: a systematic review and meta-analysis.

Coffee drinking has been associated with benefits for various health outcomes, with many attributed to the most prevalent family of polyphenols within coffee, chlorogenic acids (CGA). Whilst reviews of the association between coffee and cognition exist, evidence exploring effects of coffee-specific CGA on cognition has yet to be systematically synthesised. The purpose was to systematically review the current literature investigating the relationship between CGA from coffee and cognitive performance. A further objective was to undertake a meta-analysis of relevant randomised controlled trials (RCT). Observational and intervention studies were included if they considered coffee-based CGA consumption in human participants and applied a standardised measure of cognition. Furthermore, intervention studies were required to define the CGA content and include a control group/placebo. Studies were excluded if they examined CGA alone as an extract or supplement. A search of Scopus, PubMed, Web of Science, ScienceDirect and PsycINFO resulted in including twenty-three papers, six of which were interventions. The evidence from the broader systematic review suggests that CGA from coffee may need to be consumed chronically over a sustained period to produce cognitive benefits. However, the meta-analysis of RCT showed no benefits of coffee CGA intake on cognitive function (d = 0.00, 95% CI -0.05, 0.05). Overall, this review included a limited number of studies, the sample sizes were small, and a wide range of cognitive measures have been utilised. This indicates that further, good-quality interventions and RCT are required to systematically explore the conditions under which coffee CGA may provide benefits for cognitive outcomes.