Socioeconomic Status and Risks of Cognitive Impairment and Dementia: A Systematic Review and Meta-Analysis of 39 Prospective Studies

Background In recent decades, increased attention has been paid to the impact of socioeconomic status (SES) on cognition function and dementia, however, an ongoing debate continues to exist. The objective of our study was to explore the potential effect of SES on the risks of cognitive dysfunction and dementia. Methods PubMed, Cochrane Library, and EMBASE were searched for prospective studies from inception to 9 January 2022. Meta-analyses using random-effect models were performed, and then subgroup analyses stratified by study characteristics for specific outcomes were conducted. Results Thirty-nine prospective studies (1,485,702 individuals) were eligible for inclusion, of which 25 reported the incidence of dementia and 14 reported cognitive decline. Primary results of the meta-analyses found an elevated combined risk of cognitive impairment and dementia (relative risk [RR] = 1.31, 95% confidence interval [CI] = 1.16-1.49) in low-SES participants compared with high-SES participants. We also found an elevated risk of all-cause dementia (RR = 1.40, 95% CI = 1.12-1.74) in low-SES participants. Further subgroup analyses stratified by education, occupation, and income showed that low education subgroup (RR = 1.21, 95% CI = 1.04-1.41) and low-income subgroup (RR = 1.22, 95% CI = 1.10-1.35) had an increased combined risks of cognitive impairment and dementia, but only individuals with lower education had a higher risk of dementia (RR = 1.66, 95% CI = 1.20-2.32). Conclusions Low SES substantially increased the risk of dementia and cognitive dysfunction, suggesting that public health strategies could reduce the dementia burden by reducing social inequalities.