When summer temperatures spike, many people worry about heat-related illness. But a surprising new study shows that for women with depression, whether or not they take medication may make a real difference in how their bodies handle the heat.
Researchers at Penn State University found that women with unmedicated depression struggle more than expected when their bodies try to cool down in extreme heat. But women taking a common type of antidepressant called SSRIs performed just as well as women without depression. The study was published in the Journal of Applied Physiology.
The finding flips upside down a widespread fear that antidepressants might make people more vulnerable in hot weather. Public health guidance and social media posts have suggested that people taking SSRIs could be at higher risk during heat waves. But this research tells a different story.
"Depression interferes with how women's bodies regulate their temperatures in the heat," said Kathleen Fisher, who led the study as part of her doctoral research in kinesiology at Penn State. "Fortunately, SSRIs seem to largely restore the body's ability to respond to increases in internal temperature."
The human body cools itself in two main ways: sweating and pushing more blood to the skin so heat can escape into the air. The study found that depression slows both of these processes in women. When researchers tracked 64 women in their twenties through a heat stress test, women with untreated depression started sweating later, sent blood to their skin more slowly, and did so less efficiently than women without depression. Women taking SSRIs, however, showed responses nearly identical to those with no depression diagnosis.
In the experiment, women swallowed a tiny temperature-sensing capsule and then wore a suit filled with tubing that pumped hot water around their bodies. After ten minutes in 91°F water, the temperature was cranked up to 125°F. Researchers measured when each woman's internal body temperature rose by 1°F, which took about 45 minutes on average. During that time, they tracked skin temperature, heart rate, blood pressure, blood flow to the skin, and sweating.
The study included four groups of 16 women: those with no depression, those with depression not taking medication, those taking SSRIs, and those taking a related type of antidepressant called SNRIs. Interestingly, the two medication types diverged. While SSRIs appeared to restore normal heat responses, women taking SNRIs fell somewhere in between those with unmedicated depression and those without it.
Depression affects roughly 10% of the U.S. population and is twice as common in women, according to the researchers. SSRIs like sertraline and fluoxetine are among the most commonly prescribed medications for the condition, often alongside talk therapy.
Professor W. Larry Kenney, who supervised the research, noted that earlier Penn State studies had already shown blood vessels in women with depression dilate less effectively in the heat. This new study confirms that improved blood vessel function seen in women on SSRIs also translates to actual heat stress situations.
For people managing depression, the researchers hope these findings ease unnecessary fears about medication and heat safety.