Body weight status and onset of cognitive impairment among U.S. middle-aged and older adults.
OBJECTIVE
To examine the relationship between body weight status and onset of cognitive impairment among U.S. middle-aged and older adults.


METHODS
Study sample came from 1996 to 2010 waves of the Health and Retirement Study, consisting of 6739 community-dwelling adults born between 1931 and 1941 who were free from cognitive impairment in 1996. Body mass index (BMI) was calculated from self-reported height/weight. Cognitive impairment was defined by a composite score of 11 or lower on the immediate and delayed word recall, serial 7's, and backwards counting tests. Kaplan-Meier estimator and Cox proportional hazards model were performed to examine the association between base-year body weight status and future onset of cognitive impairment.


RESULTS
Compared with their normal weight counterparts, the unadjusted hazard ratio (HR) for cognitive impairment incidence was 2.03 (95% confidence interval: 1.38-3.00), 1.15 (1.02-1.29), 1.28 (1.14-1.43), and 1.59 (1.33-1.92) among underweight (BMI<18.5), overweight (25 ≤ BMI < 30), class I obese (30 ≤ BMI < 35), and class II obese or above (BMI ≥ 35) participants, respectively. The unadjusted relationship between obesity and cognitive impairment onset appeared stronger among females than among males. After adjusting for base-year individual sociodemographics, functional limitations and chronic conditions, the estimated associations between body weight status and cognitive impairment were attenuated but remained statistically significant for underweight participants.


CONCLUSIONS
Underweight is a robust risk factor for onset of cognitive impairment in later life. Weight management programs targeting middle-aged and older adults should focus on achieving and maintaining optimal body weight.
School of Social Work, University of Illinois at Urbana-Champaign, 1010 West Nevada Street, Urbana, IL 61801, United States. Electronic address: xxiang3@illinois.edu.
Xiaoling
X
Xiang
Department of Kinesiology and Community Health, College of Applied Health Sciences, University of Illinois at Urbana-Champaign, 2013 Huff Hall, 1206 South 4th Street, Champaign, IL 61820, United States.
Ruopeng
R
An
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015992:Body Mass Index; D001835:Body Weight; D003071:Cognition / Q000502:physiology*; D003072:Cognition Disorders / Q000453:epidemiology* / Q000523:psychology; D005260:Female; D006801:Humans; D015994:Incidence; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000453:epidemiology; D050177:Overweight; D016016:Proportional Hazards Models; D012307:Risk Factors; D016019:Survival Analysis; D013851:Thinness; D014481:United States / Q000453:epidemiology
Body weight status; Cognitive impairment; Health and Retirement Study; Older adults; Survival Analysis