Objectives: To assess the relationship between body mass index (BMI) and waist-hip ratio (WHR) and the clinical end points of cognitive impairment and probable dementia in a cohort of older women enrolled in the Women's Health Initiative Memory Study (WHIMS).
Design: Prospective, randomized clinical trial of hormone therapies with annual cognitive assessments and anthropometrics.
Setting: Fourteen U.S. clinical sites of the WHIMS.
Participants: Seven thousand one hundred sixty-three postmenopausal women aged 65 to 80 without dementia.
Measurements: Annual cognitive assessments, average follow-up of 4.4 years, including classification of incident cognitive impairment and probable dementia. Height, weight, waist, and hip measurements were assessed at baseline, and a waist-hip ratio (WHR) of 0.8 or greater was used as a marker of central adiposity.
Results: There were statistically significant interactions between BMI and WHR and incident cognitive impairment and probable dementia with and without adjustment for a panel of cognitive risk factors. Women with a WHR of 0.80 or greater with a BMI of 20.0 to 24.9 kg/m² had a greater risk of cognitive impairment and probable dementia than more-obese women or women with a WHR less than 0.80, although women with a WHR less than 0.80 and a BMI of 20.0 to 24.9 kg/m² had poorer scores on cognitive assessments.
Conclusion: WHR affects the relationship between BMI and risk of cognitive impairment and probable dementia in older women. Underweight women (BMI < 20.0 kg/m²) with a WHR less than 0.80 had a greater risk than those with higher BMIs. In normal-weight to obese women (20.0-29.9 kg/m², central adiposity (WHR ≥ 0.80) is associated with greater risk of cognitive impairment and probable dementia than in women with higher BMI. These data suggest that central adiposity as a risk factor for cognitive impairment and probable dementia in normal-weight women.
© 2011, Copyright the Authors. Journal compilation © 2011, The American Geriatrics Society.