A new study suggests that taking antidepressants impairs empathy, while the experience of depression itself does not.

Empathy is an integral part of human socialization. It’s how we show others that we understand and care about their emotional state. But what happens if the medications you’re taking diminish that ability? A new study suggests that taking antidepressants impairs empathy, while the experience of depression itself does not.

The research was led by Markus Rütgen and Claus Lamm, at the University of Vienna, Austria. It was published in the journal Translational Psychiatry.

Previous researchers have suggested that depression itself results in reduced empathy toward others. However, that research is limited by a significant flaw—it has almost entirely been conducted in people taking medications. An additional problem with previous research is that it focused on self-reported empathy—which is unreliable, especially in depression studies.

In the current study, the researchers aimed to resolve these two flaws with their research design. First, they compared people with a diagnosis of depression (“acute MDD”) not taking antidepressants to people without a diagnosis of depression (“healthy controls”). They then did the same test after participants had three months of antidepressant use. Three different antidepressants were used: escitalopram, venlafaxine, and mirtazapine, which each have slightly different effects on the serotonin system.

Also, in addition to asking participants to self-report their levels of empathy, the researchers used an fMRI brain scan. They used the standard fMRI tests for functional connectivity among parts of the brain associated with empathic responses to pain. While receiving the brain scan, participants watched videos of a person experiencing pain for about six-and-a-half minutes.

The results? People with a diagnosis of depression were no different from “healthy controls” in terms of empathic response as measured by the fMRI.

The researchers write that this indicated “a ‘normal’ empathic response in patients with acute MDD before they underwent antidepressant treatment.”

However, after three months of antidepressant treatment, people had much less activation in the areas of the brain associated with empathy. There was no difference based on which antidepressant was used.

Interestingly, self-reported empathy also changed: after participants took antidepressants for three months, they reported that it was significantly less unpleasant to watch a person experiencing pain for six-and-a-half minutes. According to the researchers:

“After three months of therapy, patients showed decreased neural responses in a priori selected brain areas that are reliably activated by empathic pain (bilateral AI and aMCC), and reported reduced self-experienced unpleasant affect in response to the pain of others.”

The study, therefore, demonstrated that antidepressant medications make it easier to watch others experience pain and that this effect is detectable in the brain.

In their conclusion, the researchers suggest that a lack of empathy toward others “might be an advantageous side effect with a protective function.”

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Rütgen, M., Pletti, C., Tik, M., Kraus, C., Pfabigan, D. M., Sladky, R., . . . Lamm, C. (2019). Antidepressant treatment, not depression, leads to reductions in behavioral and neural responses to pain empathy. Translational Psychiatry, 9(164). https://doi.org/10.1038/s41398-019-0496-4 (Link)