Body roundness index linked to depression risk in older adults with dementia

New research indicates that a specific measurement of body fat distribution may help identify depression risk in older adults experiencing cognitive decline. Individuals with dementia who scored highest on the body roundness index were more than three times as likely to have depression compared to those with lower scores. The findings were published in the Journal of Health Psychology.

Dementia is a major global health concern characterized by objective cognitive deficits and functional impairment. Around 45 percent of dementia cases involve risk factors that people can theoretically modify. These modifiable risks include low educational attainment, sensory deficits, depression, and metabolic diseases.

Obesity has emerged as an especially prominent predictor of adverse cognitive outcomes in aging populations. Excess fat tissue can provoke chronic, low-grade systemic inflammation throughout the body. This persistent inflammation can disrupt normal neuronal activity and accelerate the physical deterioration of the brain.

Inflammation also increases oxidative stress and disrupts the body’s natural hormone response systems. These biological shifts are known to contribute to depressive symptoms in older populations.

Assessing body fat in older adults presents specific methodological challenges for medical professionals. The most common measurement is the body mass index, which is calculated by dividing a person’s weight by the square of their height. This traditional metric fails to distinguish between fat mass and lean muscle mass.

In older adults, muscle depletion and bone loss are common physical changes. As a result, calculating a standard body mass index might underestimate the true amount of fat tissue in a senior citizen, obscuring their actual metabolic health.

Waist circumference is another traditional metric used in medical clinics. It measures the distance around the abdomen but does not reliably indicate whether fat is sitting just beneath the skin or packed deep around the internal organs.

Clarissa Pacheco da Rocha Fernandes, a researcher at the D’Or Institute for Research and Education in Brazil, led the new investigation alongside corresponding author Felipe Kenji Sudo and their colleagues. The team wanted to evaluate alternative measurements that might better capture body fat distribution in older adults.

The researchers focused on newer metrics like the body roundness index. The body roundness index relies on a mathematical model that visualizes the human shape as an oval.

By combining a person’s height and waist circumference, the body roundness index estimates central fat accumulation more accurately than standard weight-to-height ratios. The researchers wanted to know if this specific index could predict mood disturbances in people experiencing cognitive decline.

The researchers designed an observational study involving 601 individuals aged 60 to 91. These participants were evaluated at a specialized memory clinic in Brazil between 2015 and 2024.

Medical professionals conducted standardized clinical interviews and physical examinations for every participant. They measured height, weight, and waist circumference to calculate the various body indices.

Trained neuropsychologists administered a battery of cognitive tests to assess memory, language, and executive function. Based on these standardized evaluations, 239 participants were formally diagnosed with dementia.

To measure mood, the participants completed a widely used 15-item questionnaire designed specifically to detect geriatric depression. The researchers also collected data on lifestyle habits, such as physical activity levels and alcohol consumption, alongside the participants’ medical histories.

The research team calculated several different body measurements for each person. They then ran statistical models to see if higher body fat measurements corresponded to higher rates of clinical depression.

In the total group of 601 older adults, none of the body measurements were associated with depression. The results across the general clinic population were not statistically significant.

When the researchers restricted their analysis to the 239 individuals diagnosed with dementia, they observed a distinct pattern. In this specific subgroup, the body roundness index was strongly linked to depression.

Individuals with dementia who scored in the highest quarter of the body roundness index had more than three times the odds of experiencing depression compared to those in the lowest quarter. This association remained mathematically robust even after adjusting for age, sex, education level, and general anxiety.

The models also accounted for medical conditions like hypertension, diabetes, and abnormal cholesterol levels. The body roundness index maintained its predictive power independent of these other health issues.

The traditional measurements did not perform as well in the analysis. Body mass index and waist circumference showed a non-linear relationship with depression in the dementia group.

Specifically, these traditional metrics displayed a U-shaped curve when plotted on a graph. Both the lowest and the highest measurements were associated with elevated odds of depression, which makes them less reliable as simple screening tools for mood disorders.

The researchers suspect the body roundness index performs better because it captures abdominal fat more precisely. Central adiposity is known to influence brain networks involved in attention and processing speed, which are often impaired in late-life depression.

Emerging evidence suggests that abdominal fat might alter specific genetic and molecular pathways in the brain. Obesity-related mechanisms can impair the brain’s ability to form new synaptic connections, potentially increasing a person’s vulnerability to mood disorders.

The study has a few limitations that readers should keep in mind. Because the research relied on a cross-sectional design, it represents a single snapshot in time.

This observational design cannot prove that abdominal fat causes depression in older adults with dementia. It can only demonstrate that the two conditions are present at the same time in this specific population.

The study took place at a specialized tertiary memory clinic, and the participants were all highly educated compared to the regional average. As a result, the findings might not fully represent the general population of older adults living in the wider community.

The doctors diagnosed dementia using clinical criteria and cognitive tests rather than biological markers. The study did not use brain imaging or spinal fluid analysis to confirm the specific underlying diseases, such as Alzheimer’s disease or vascular dementia.

The body measurements are indirect estimates of fat tissue. They do not offer the precision of advanced imaging techniques, such as dual-energy X-ray absorptiometry or magnetic resonance imaging, which directly measure the volume of internal fat.

Future investigations should track patients over multiple years to see if changes in body shape precede the onset of mood disorders. Longitudinal tracking would help scientists map the exact biological pathways linking fat tissue to brain health.

Identifying depression risk is a high priority in geriatric care because mood disorders can accelerate cognitive decline in dementia patients. Simple, inexpensive screening tools like the body roundness index could eventually help doctors provide targeted preventative treatments.

The study, “Body roundness index as a predictor of depression in dementia: A cross-sectional study,” was authored by Clarissa Pacheco da Rocha Fernandes, Natalia Oliveira, Rejane Soares, Fernanda Rodrigues, Gabriel Bernardes, Raquel Quimas Molina da Costa, Naima Assuncao, Alina Teldeschi, Felippe Mendonca, Victor Calil, Andrea Silveira de Souza, Claudia Drummond, Fernanda Tovar-Moll, Paulo Mattos, and Felipe Kenji Sudo.