Education, Socioeconomic Status, and Intelligence in Childhood and Stroke Risk in Later Life A Meta-analysis

Background: Stroke is the second most common cause of death, and a common cause of dependency and dementia. Adult vascular risk factors and socioeconomic status (SES) are associated with increased risk, but less is known about early life risk factors, such as education, childhood SES, or intelligence (IQ). Methods: We comprehensively searched Medline, PsycINFO, and EMBASE from inception to November 2015. We included all studies reporting data on >50 strokes examining childhood/premorbid IQ, SES, and education. Two reviewers independently screened full texts and extracted and cross-checked data, including available risk factor adjustments. We meta-analyzed stroke risk using hazard ratios (HR), odds ratios (OR), and mean differences (MD). We tested effects of study and participant characteristics in sensitivity analyses and meta-regression, and assessed heterogeneity and publication bias. Results: We identified 90 studies examining stroke risk and education (79), SES (10), or IQ (nine) including approximately 164,683 stroke and over 5 million stroke-free participants. Stroke risk increased with lower education (OR = 1.35, 95% CI = 1.24, 1.48), SES (OR = 1.28, 95% CI = 1.12, 1.46), and IQ (HR = 1.17, 95% CI = 1.00, 1.37) in studies reporting point estimates, with similar associations for MD. We found minimal publication bias. Between-study heterogeneity was partly explained by participant age and case ascertainment method. Conclusions: Education, childhood SES, and intelligence have modest but important associations with lifetime stroke, and hence dementia, risks. Future studies distinguishing between the individual and combined effects of education, childhood SES and intelligence are needed to determine the independent contribution of each factor to stroke risk.