Body Roundness Index Predicts Depression in Dementia Better Than BMI

A cross-sectional study in the *Journal of Health Psychology* examined whether the Body Roundness Index (BRI), a shape-based metric using height and waist circumference, predicts depressive symptoms in older adults with dementia. Conducted at a Brazilian memory clinic (2015-2024), it included 601 participants aged 60–91.

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Dementia, a neurodegenerative disease causing progressive memory loss, often co-occurs with under-detected depression. Excess body weight, especially central adiposity, is a modifiable risk factor for cognitive decline and mood disorders, yet BMI may underestimate adiposity in older adults because of age-related muscle and bone loss.

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Participants had at least eight years of education, completed medical interviews, and underwent physical exams measuring height, weight, and waist. Researchers calculated BMI, waist circumference, Waist-to-Height Ratio, Conicity Index, and BRI. Cognitive testing diagnosed dementia in 239 participants. Depression was assessed with a 15-item questionnaire; scores >= 5 indicated depression.

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In the full sample, no body-fat metric correlated with depression. Among the 239 dementia patients, 36 % were depressed. The highest BRI quartile had over three times the odds of depression versus the lowest quartile, after adjusting for age, sex, education, and comorbidities. BMI and waist circumference showed no association.

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Lead author Dr. Felipe Kenji Sudo of the D’Or Institute said BRI captures central adiposity information that traditional obesity screens miss in dementia patients. He noted the study suggests a link between metabolic health and emotional well-being and recommends integrating simple shape-based measures into routine geriatric care.

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The authors note the cross-sectional design limits causal inference and the clinic sample may limit generalizability. Reliance on formula-based estimates rather than imaging introduces uncertainty about the amount of visceral fat.

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Longitudinal studies will test whether BRI predicts incident depression and examine links with diet, body composition, and other neuropsychiatric outcomes. The team also recommends imaging validation of BRI.

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• “Depression is very common in people with dementia, but it is not always easy to recognize or anticipate in everyday clinical practice.” — Felipe Kenji Sudo, MD, D’Or Institute

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• “What surprised us was that we did not find positive results for the measures most commonly recommended to screen for obesity, such as body mass index and waist circumference.” — Felipe Kenji Sudo

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• “Our findings suggest that, in people with dementia, greater body fat accumulation may be linked to a higher risk of depressive symptoms.” — Felipe Kenji Sudo

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• “While this does not prove cause and effect, it highlights how closely emotional well-being and metabolic health may be connected in dementia.” — Felipe Kenji Sudo

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