Weight Trajectory over 20 Years and Likelihood of Mild Cognitive Impairment or Dementia Among Older Women.

Objectives: The association between weight change and cognition is controversial. We examined the association between 20-year weight change and cognitive function in late life.

Design: Cohort study.

Setting: Study of Osteoporotic Fractures (SOF).

Participants: One thousand two hundred eighty-nine older, community-dwelling women (mean baseline age 68 (65-81) and 88 (82-102) at cognitive testing).

Measurements: Study of Osteoporotic Fractures participants had body weight measured repeatedly over 20 years (mean 8 weights). Adjudicated cognitive status was classified as normal (n = 775) or mild cognitive impairment (MCI)/dementia (n = 514) at Year 20. Logistic models were used to evaluate whether absolute weight change, rate of weight loss per year, presence of abrupt, unrecovered weight loss, and weight variability were associated with MCI or dementia.

Results: Women with greater rate of weight loss over 20 years had increased chance of developing MCI or dementia. In age/education/clinic-adjusted "base" models, each 0.5 kg/yr decrease resulted in 30% increased odds of MCI/dementia (OR = 1.30 [95% CI: 1.14, 1.49]). After adjustment for age, education, clinic, depression, and walking speed, there was 17% (OR = 1.17 [95% CI: 1.02, 1.35]) increased odds of MCI/dementia for each 0.5 kg/yr decrease in weight. In base models, variability in weight was significant. Each 1% average deviation from each woman's predicted weight curve was associated with 11% increased odds of MCI/dementia (OR = 1.11 [95% CI: 1.04, 1.18]). The estimate was attenuated after full adjustment (OR = 1.06 [95% CI: 0.99, 1.14]). The presence of an abrupt weight decline was not associated with MCI/dementia.

Conclusions: Rate of weight loss over 20 years was associated with development of MCI or dementia in women surviving past 80 years, suggesting that nutritional status, social-environmental factors, and/or adipose tissue function and structure may affect cognitive function with aging.