Brown Fat Linked to Lower Rates of Anxiety and Depression

When people think about body fat, they often picture the number on the scale or a growing waistline. But research into brown fat is drawing attention to a different kind of connection: patients whose medical scans revealed this tissue had fewer recorded diagnoses of anxiety and depression.

Brown fat, found in areas including the neck, near the collarbones and under the arms, generates heat when activated by cold. It also absorbs the radioactive glucose tracer used in certain medical scans, making it visible in imaging results.

“What surprised us most was that no previous study had documented a potential link between brown fat and mood,” said Nicolás Gómez-Banoy, an endocrinologist and researcher at Rockefeller University.

In a 2021 study, the research team linked brown fat to lower rates of diabetes and cardiovascular disease. Following those findings, the researchers expanded their investigation to hundreds of medical diagnoses.

They examined records from more than 100,000 patients at Memorial Sloan Kettering Cancer Center in New York, analyzing PET/CT scans taken for clinical reasons alongside patients’ diagnoses and medication histories.

The researchers matched patients with detectable brown fat to those without it based on age, sex, body mass index and outdoor temperature. Among the matched groups, 5.4% of patients with detectable brown fat had a recorded diagnosis of depressive episodes, compared with 8.2% of those without it. Anxiety disorders were also less common among patients with detectable brown fat.

These associations persisted after the researchers accounted for smoking history, cancer type and stage, treatment and other factors.

To investigate whether the amount and location of brown fat mattered, the team also used artificial intelligence.

A machine-learning tool helped measure brown-fat volume and glucose uptake in about 8,700 patients with detectable brown fat. These measurements were used to estimate brown-fat activity across six regions of the body.

Higher activity around the armpits was particularly associated with better cardiovascular and metabolic health. The psychiatric findings, however, came from a separate comparison of recorded diagnoses.

Patients with detectable brown fat also had lower blood sugar levels, including lower levels of a marker that reflects long-term blood glucose.

Gómez said the most likely explanation is that people with brown fat tend to have better metabolic profiles, healthier fat distribution and lower levels of inflammatory markers — all factors previously associated with better psychiatric outcomes.

The researchers also found that patients taking certain selective serotonin reuptake inhibitors (SSRIs), a class of antidepressants used to treat depression and anxiety, were less likely to have detectable brown fat. The association remained after accounting for relevant psychiatric diagnoses and was consistent with previous human research suggesting that these medications may reduce brown-fat activity.

The team also examined medication records for drugs that might activate brown fat. Patients taking certain blood-pressure medications were more likely to have detectable brown fat. The researchers tested one of these drugs, losartan, in cultured brown-fat cells and in mice.

Losartan increased brown-fat activity, and treated mice used more energy. However, these experiments did not assess anxiety or depression.

Gómez cautioned that the study was retrospective and therefore established an association, not a cause-and-effect relationship.

The research was conducted among patients at a single cancer center, and more than three-quarters of the individuals in the matched groups were women. The paper also notes that cancer types and treatments differed between groups, meaning their potential influence on the findings cannot be ruled out despite statistical adjustments.

Gómez said future studies testing drugs or other approaches to activate brown fat should also monitor whether patients experience changes in anxiety or depression.