Association of early life BMI with dementia risk: Findings from a pooled cohort analysis

Abstract

AbstractBackgroundThe evidence about the timing and influence of some key cardiovascular risk factors, such as Body Mass Index (BMI), on the risk of Alzheimer disease and other dementias remains debatable. Studies have shown that high midlife BMI increases the risk of dementia, while high late life BMI may be protective; however, relatively little is known about the role of early life BMI on the risk of Alzheimer Disease and other dementias.MethodWe studied 5,104 older adults from two studies, the Cardiovascular Health Study (CHS, n=2,909) and the Health, Aging and Body Composition study (Health ABC, n=2,195) study. For CHS‐Health ABC older adults, we imputed early and midlife BMI, beginning at age 18, using linear mixed models applied to a pooled cohort which also included young and middle‐aged adults from CARDIA and MESA. BMI was then summarized by time‐weighted averages in early (ages 20‐49), mid (ages 50‐69), and late life (ages 70‐89). In CHS, dementia was adjudicated by an expert committee following a detailed neuropsychological test battery and neurological examination. In Health ABC, dementia diagnosis was determined based on hospitalization ICD codes, dementia‐related drugs and decline on the Modified Mini Mental State Examination. All analyses were sex stratified.ResultCHS‐Health ABC participants had a mean age of 72.6 years (SD=4.2) at enrollment, 18% were black and 56% were women. For women, dementia risk increased with higher early life BMI: it was 1.8 times higher among those who were overweight (OR=1.8; 95% CI=1.31‐2.54) and 2.5 times higher among those who were obese (OR=2.45; 95% CI=1.47‐4.06), from pooled logistic regression models adjusted for midlife and late life BMI. For men, dementia risk increased with higher early life (Obese OR=2.47; 95% CI=1.46‐4.19) and mid life BMI (Overweight OR=1.51; 95% CI=1.11‐2.05 and Obese OR=2.00; 95% CI=1.16‐3.42), in models also adjusted for late life BMI. For both women and men, dementia risk decreased with higher late life BMI.ConclusionOur study is the first to report heightened dementia risk with higher early life BMI, for both women and men. Accounting for early life BMI, we found no effect for midlife BMI on dementia risk among women.