Yoga and omega-3 as effective as therapy for depression in pregnancy, research finds
SSRIs may help women with depression tolerate extreme heat, with responses more like those without depression, a laboratory study suggests.
Selective serotonin reuptake inhibitors, or SSRIs, are medicines commonly used to treat mental health conditions including depression and anxiety.
Media reports, social media posts and the US Centers for Disease Control and Prevention have suggested SSRIs may increase vulnerability to heat-related illness.
However, researchers found that women with clinical depression who took an SSRI may withstand extreme heat better than those not treating their depression with medication.
The study was carried out by researchers in the Penn State Department of Kinesiology.
Kathleen Fisher, first author of the study, said: “The human body primarily cools itself in two ways, by sweating and by increasing blood flow to the skin so that heat can be released to the environment.
“This study showed that depression interferes with how women’s bodies regulate their temperatures in the heat. Fortunately, SSRIs seem to largely restore the body’s ability to respond to increases in internal temperature.”
The team compared women without depression with those diagnosed with the condition, including women taking different types of antidepressants.
When their body temperatures rose, women with untreated depression were slower to begin sweating and increasing blood flow to the skin.
Their bodies were also less efficient at pumping blood to the skin than those of women without depression and women taking an SSRI.
Depression affects about 10 per cent of the US population and is twice as common among women, the researchers said.
SSRIs, including sertraline and fluoxetine, and serotonin and noradrenaline reuptake inhibitors, or SNRIs, including duloxetine and venlafaxine, are commonly prescribed alongside counselling to treat depression.
Previous research suggests depression disrupts the body’s ability to regulate temperature.
Penn State researchers had previously found that blood vessels dilated less effectively in women with depression. Dilation allows blood vessels to widen, helping more blood reach the skin to cool the body.
Women taking SSRIs showed improved blood vessel dilation similar to that seen among people without depression.
The latest study examined whether the same improvement occurred during heat stress.
Researchers recruited 64 women, almost all in their 20s. The group included 16 without depression and 16 with depression who were not taking medication.
A further 16 had depression and were taking an SSRI, while 16 had depression and were taking an SNRI.
Participants swallowed a small capsule that transmitted their internal body temperature throughout the experiment.
They then wore a suit fitted with tubes that allowed researchers to pump heated water through it.
After 10 minutes of adjusting to water at 91°F, around 33°C, the temperature was raised to 125°F, around 52°C.
The experiment ended when each participant’s internal temperature had risen by 1.8°F, or 1°C. This took an average of 45 minutes.
Researchers also measured skin temperature on the arm, calf, chest and thigh, along with heart rate, blood pressure, blood flow to the skin and sweating.
Professor W Larry Kenney, a study co-author, said: “The water pumped into the suit was 125 F, causing skin temperature to rise to about 100 F.
“As the skin continued to be heated to temperatures similar to sitting in a hot tub, the women’s internal temperature continued to rise.”
Women with untreated depression were slower to begin sweating and increasing blood flow to the skin than women without depression.
When blood flow to the skin increased, it was less efficient. Despite beginning to sweat later, women with untreated depression did not sweat less overall.
Women taking SSRIs responded to heat in a similar way to women without depression.
By contrast, women taking SNRIs responded similarly to those with untreated depression. SSRIs therefore normalised responses to heat stress, while SNRIs did not.
Researchers found no differences in blood pressure between the four groups.
Fisher said: “Up until now, there has been very little data on how depression or any of these classes of antidepressive drugs affect people’s responses to heat stress.
“This study took the first step toward understanding how women with depression, whether taking medications or not, may respond to extreme heat.”
Kenney said the findings challenged common beliefs that SSRIs increase vulnerability to heat.
He said: “In prior studies, my collaborators and I have identified how several factors, especially age, sex, and activity level, contribute to risk from extreme heat.
“Additionally, there has been widespread concern that many medications contribute to heat vulnerability, but the research evidence behind the risks of many medicines is often thin or nonexistent.
“Both physicians and people taking SSRIs should be aware that these medications do not seem to contribute to heat vulnerability. Rather, SSRIs improve heat tolerance in depression.”
