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Changes in body mass index in young adulthood and late‐life dementia risk in a large diverse cohort
Author(s) -
Gilsanz Paola,
Mayeda Elizabeth Rose,
George Kristen M.,
Peterson Rachel,
Eng Chloe W.,
Glymour M Maria,
Quesenberry Charles P,
Whitmer Rachel A.
Publication year - 2020
Publication title -
alzheimer's and dementia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.713
H-Index - 118
eISSN - 1552-5279
pISSN - 1552-5260
DOI - 10.1002/alz.046496
Subject(s) - underweight , body mass index , medicine , dementia , overweight , obesity , hazard ratio , demography , cohort , gerontology , pediatrics , confidence interval , disease , sociology
Background Midlife obesity is associated with dementia risk, yet the relationship between body mass index (BMI) during young adulthood and dementia is unclear. Method We evaluated 6,947 members of an integrated healthcare delivery system who underwent clinical exams in their 20s and 30s starting in 1964‐1973 and were members as of 1/1/1996. Individuals were classified as underweight (18.5‐25.0 kg/m 2 ), normal weight (18.5‐25.0 kg/m 2 ), overweight (25.0‐30.0 kg/m 2 ), or obese (30+ kg/m 2 ) based on BMI calculated with height and weight measured during the first MHC visit from each age range. Changes in BMI were classified as: 1) consistently normal‐/over‐weight, 2) obesity onset, 3) obese to normal‐/over‐weight, and 4) consistently obese. Dementia diagnoses were abstracted from electronic medical records from 1/1/1997‐9/30/2017. Cox proportional hazard models adjusted for age (as time scale), race/ethnicity, sex, and education evaluated associations between BMI and BMI change categories with dementia risk overall and by sex. Result The sample was 61.7% female, 6.7% were obese in their 20s, 11.1% were obese in their 30s, and 3.5% experienced dementia during follow‐up. Individuals who were obese in their 20s were at elevated dementia risk (HR=2.14, 95% CI:1.43‐3.20) compared to normal weight counterparts; there was no difference in dementia risk among underweight individuals (HR=0.70, 95% CI:0.31‐1.59) or overweight individuals (HR=1.80, 95% CI 0.79‐1.49). Individuals who were overweight (HR=1.35, 95% CI:1.00, 1.82) and those who were obese (HR=1.76, 95% CI: 1.21‐2.57) in their 30s were at elevated dementia risk compared to normal weight counterparts; there was no association between being underweight and dementia risk (HR=0.59, 95% CI: 0.19‐1.86). Individuals who were consistently obese had more than double the risk of dementia (HR=2.42, 95% CI:1.61‐3.65) than consistently normal‐/over‐weight individuals; there was no association between obesity onset or going from obese to normal‐/over‐ weight and dementia risk. The associations between BMI in one’s 20s, BMI in one’s 30s, and BMI change with dementia risk did not significantly differ by sex. Conclusion Obesity during young adulthood (i.e. 20s and 30s) and being overweight during one’s 30s were associated with elevated dementia risk. Consistent obesity during young adulthood more than doubled an individual’s risk of dementia.