Everything Under The Sun: Research On Using Heat To Treat Depression

Professor Charles Raison

In asking the question of whether a small rise in body temperature can relieve symptoms of depression researchers at the University of Wisconsin-Madison's CENTER FOR HEALTHY MINDS set out to test this idea in a small study sample, led by Professor Charles Raison.

Researchers utilized the Hamilton Depression Rating Scale (HDRS) to assess level of depression in this double-blind study. The findings revealed that 60 percent of the subjects had a positive response, while 40 percent met the criteria for remission of depression.

Professor Raison said, "Our hope is to find better and faster-acting treatments for depression than the antidepressants currently in use. We think that using heat to stimulate the skin activates serotonin-producing cells in the midbrain, which then produce a change in how the brain functions. In a way, one might think of this pathway from the skin to the brain as a deep-brain stimulator crafted by evolution. We tap into this pathway because heat makes the brain feel happy.

To raise body temperature, researchers used a whole-body hyperthermia device to raise the temperatures of 16 subjects to 101.3 degrees F. Fourteen subjects were given a sham treatment that also had those subjects lying in the hyperthermia device, but utilizing just a small amount of heat.

According to Professor Raison, "Our sham intervention was so realistic that most of the participants (10 of 14) thought they were receiving the real treatment. That is important because it suggests the antidepressant response was not due primarily to placebo factors associated with the treatment."

In the end, the true hyperthermia treatment resulted in a rise in HDRS scores by a mean of 5.67 points more than the sham treatment produced. These changes were measured at six weeks after each intervention. Subjects in both groups reported only minor adverse effects, while their self-reports described some lessening of symptoms. Professor Raison noted, "We were surprised to see that the effect (of reduced depression symptoms) was still present six weeks after the initial treatment."

In a previous study, Christopher Lowry, an associate professor of integrative physiology at the University of Colorado-Boulder, had demonstrated that whole-body heat treatment activates brain neurons that produce serotonin, something that SSRI antidepressants also do. As Professor Lowry said, "We know that warming the skin activates areas of the brain where activity is low in depressed patients."

Interestingly, in certain parts of Europe, hyperthermia has been used for a number of years to fight cancer, although these treatments typically raise body temperatures much higher than this study did.

The type of heat device that was used in the study.

Although the results of this study were positive, researchers caution against generalizing the results due to small sample size. Further research is needed to determine optimal delivery method, amount of temperature rise to give maximum benefit, and the amount of time exposed to heat that produces the best results.