Data from more than 20,000 people has revealed an intriguing link between depression and body temperature – in particular, people with depression recorded slightly higher temperatures. Although more questions remain to be answered, the research raises the possibility of introducing heat-based treatments into mental health care in the future.
The study lasted seven months and started in early 2020. It involved volunteers from 106 countries. Participants tracked their body temperature data using a wearable Oura smart ring, a commercially available fitness tracker. The main aim of the study, called TemPredict, was to assess whether temperature tracking could be a useful tool for the early detection of COVID-19, results reported as early as 2022.
In addition to recording their body temperature once a day, participants completed a monthly survey that included a diagnostic questionnaire on depression symptoms.
Examination of the data has now revealed that people with higher levels of depression symptoms tended to have higher body temperature readings. There was also a trend toward more severe depression in people whose body temperature remained more stable over a 24-hour period, but this finding was not statistically significant.
Mean self-reported (A) and wearable-assessed (B) body temperatures based on depression symptom scores (red indicates most severe depression symptoms).
It’s not the first time depression and body temperature have been linked, albeit tentatively, but pinpointing the cause of some of the observed differences has proven more challenging. While this large study undoubtedly helps add more pieces to the puzzle, it is still not possible to say with certainty whether depression increases body temperature, or whether a higher-than-average body temperature is a risk factor for depression.
We also don’t know whether the higher temperatures in depressed people are due to their bodies generating more heat than normal, or whether their ability to regulate their temperature is reduced.
It is this that the study’s lead author, Ashley Mason, associate professor of psychiatry at the University of California San Francisco Weill Institute for Neurosciences, wants to explore further. A small amount of evidence suggests a potential benefit for heat-based treatment for depression, such as saunas or hot yoga. It may be that artificially raising a person’s temperature causes the body to initiate self-cooling mechanisms, such as sweating.
“Ironically, warming people up can actually lead to a reduction in body temperature that lasts longer than simply cooling people down directly, such as with an ice bath,” Mason explained in a statement. “What if we could monitor the body temperature of people with depression to properly time heat-based treatments?”
Depression is a common problem, with an estimated one in five American adults having been diagnosed with the condition. As a result, the use of antidepressants has reached an all-time high in some regions, but they are not effective for everyone and can come with troubling side effects.
The scientific quest to develop new and better treatments for depression continues and includes research into psychedelics, medications such as ketamine and alternative therapies such as sensory deprivation. Perhaps, the authors suggest, heat treatments could one day be part of that package.
“To our knowledge, this is the largest study to date examining the association between body temperature – assessed using both self-report methods and wearable sensors – and depressive symptoms in a geographically broad sample,” said Mason.
“Given the rising rates of depression in the United States, we are excited about the possibilities of a new treatment approach.”
The research has been published in Scientific Reports.