Accelerated weight loss and incident dementia in an elderly African-American cohort

Objectives: To examine the association between changes in body mass index (BMI), dementia, and mild cognitive impairment (MCI).

Design: Prospective observational study.

Setting: Urban community in Indianapolis, Indiana.

Participants: Participants were African Americans aged 65 and older enrolled in the Indianapolis Dementia Project and followed through 2007. This analysis included 1,331 participants who did not have dementia at their first BMI measurement.

Measurements: Cognitive assessment and clinical evaluations were conducted every other year to identify participants with dementia or MCI during 12 years of follow-up (mean follow-up 6.4 years). BMI measures; alcohol and smoking history; and medical conditions including history of cancer, hypertension, diabetes mellitus, heart attack, stroke; and depression were collected at each follow-up evaluation. Mixed-effect models were used to examine the differences in BMI between participants who developed dementia or MCI and those who did not, adjusting for covariates.

Results: Mean BMI at baseline was 29.8 ± 5.7 for women and 28.3 ± 4.8 for men. Participants with incident dementia or MCI had greater decline in BMI than those without (P=.02 for dementia, P=.04 for MCI). BMI in participants with incident dementia, MCI, and normal cognition did not differ 12 or 9 years before diagnosis, but 6 years before diagnosis, participants with incident dementia had significantly lower BMI than participants with normal cognition (P=.03), as did participants with MCI (P=.006).

Conclusion: Decline in BMI appears to be an early marker for dementia. There is a need for the close monitoring of weight loss in older adults.