Study Finds Overweight Dementia Patients Have Longer Survival Than Normal-Weight Peers
People with dementia who are overweight or obese at diagnosis may have a lower risk of death than those in the normal weight range, according to a study published in the Journal of Alzheimer’s Disease.
Researchers analysed data from the US Health and Retirement Study, following 4,523 people who were dementia-free when they entered the study and later developed dementia. The analysis covered data collected between 1998 and 2022, allowing researchers to examine weight before and around dementia diagnosis.
Compared with people with a normal body mass index (BMI), those who were overweight had a 16% lower mortality risk. The reduction was 27% among people with class 1 obesity, defined as a BMI of 30 to 34.9, and 22% among those with class 2 or 3 obesity, with a BMI of 35 or higher.
The associations remained after researchers accounted for chronic diseases, smoking and demographic characteristics. Analyses of potential bias, including weight loss before diagnosis and survivor bias, did not appear to explain the observed association.
People with dementia can lose weight years before diagnosis, with weight loss often accelerating close to disease onset. This means some people classified as normal weight at diagnosis may already have more advanced disease and nutritional vulnerability.
Greater energy reserves or muscle mass could help people cope with wasting, reduced appetite and eating difficulties. However, the biological explanation remains uncertain.
Importantly, the study does not show that gaining weight improves survival and does not suggest that people with dementia should become overweight or obese. Instead, weight status at diagnosis could provide prognostic information and highlight the importance of nutrition and preventing unhealthy weight loss during dementia care.
Further research is needed to understand the association and determine how nutritional support may affect outcomes.
REFERENCE: Chang, V. W., et al. (2026). Body mass index and mortality in incident dementia. Journal of Alzheimer’s Disease. DOI: 10.1177/13872877261491694
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