Sarcopenia and cognitive impairment: A systematic review and meta-analysis

Sarcopenia and cognitive impairment are two of the most prevalent causes of disability in the aging population. Despite the vast amount of research that has been done to quantify the association between these two conditions, extensive systematic reviews and meta-analyses remain limited. We performed a systematic review using the PubMed, EMBASE, Scopus, and Google Scholar databases. Sarcopenia was defined as the loss of skeletal muscle mass and muscle function, as measured by muscle strength or performance. Cognitive impairment was diagnosed by validated cognitive or neuropsychological tests. We identified 303 potentially relevant articles in the initial search. Observational studies quantifying a relationship between sarcopenia and cognitive impairment were selected. Information was extracted from 15 studies, and random-effects models were used for the meta-analysis. The pooled odds ratios for cognitive impairment for patients with sarcopenia compared with patients without sarcopenia were 2.85 (95% confidence interval: 2.19–3.72) in the unadjusted analysis and 2.25 (95% confidence interval: 1.70–2.97) in the adjusted meta-analysis. These results remained constant in subgroup analyses by study population, study region, the definition of sarcopenia, and cognitive impairment. Although half of the studies (8 out of 15) were of fair quality, we conducted a sensitivity analysis to exclude studies with fair quality and obtained similar results. Sarcopenia is associated with an increased risk of cognitive impairment independent of study population, the definition of sarcopenia, and cognitive impairment. This suggests the importance of the early recognition of sarcopenia for the prevention of cognitive impairment in clinical practice.