Change in cognition and body mass index (BMI) in relation to preclinical dementia

To investigate whether cognitive decline drives weight loss in the early stages of dementia, this study examined the longitudinal association between body mass index (BMI) and cognitive capacities in individuals who did or did not later develop dementia. By using three NEAR population-based studies: The Swedish Adoption/Twin Study of Aging (SATSA), Ageing in Women and Men: A Longitudinal Study of Gender differences in Heath Behavior and Health among Elderly (GENDER), and Origin of Variances in the Oldest-Old: Octogenarian Twins (OCTO-Twin), changes in BMI and cognitive capacities were investigated among 1957 persons aged between 50 and 89 years.

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Weight loss in the early stages of dementia is not driven by cognitive decline
Among those who did develop dementia, higher BMI predicted steeper cognitive decline across all age groups, but cognitive abilities did not drive changes in BMI. Among those who did not develop dementia, BMI and cognitive capacities stabilized each other during aging, such that a stable BMI predicted a more stable cognitive ability, and vice versa. In conclusion, weight loss in the early phases of dementia is not driven by cognitive decline. Thus, weight loss may be a warning sign of dementia even in the absence of decreasing cognitive capacities.

Photo of Ida Karlsson, first author of the study

Karlsson I. K, Zhan Y, Gatz M, Reynolds C. A, Dahl Aslan A. K. Change in cognition and body mass index in relation to preclinical dementia. Clin Transl Sci. 2021; 7(1): e12176. https://doi.org/10.1002/trc2.12176.