Medications do more than treat an illness: Certain ones may also make you more considerate or selfish. A new study finds two common medications, an antidepressant and a treatment for Parkinson's disease, actually alter your moral compass, reports Medical Daily. Researchers assigned 89 healthy people a dose of the serotonin-boosting anti-depressant citalopram or a placebo, while 86 healthy people were given the dopamine-enhancing drug levodopa or a placebo. They were then separated into pairs of "deciders" and "receivers." In each of 170 trials, deciders chose to receive a certain number of mildly painful electric shocks for payment, up to 20 shocks and $30 per trial. The catch was that they also decided how many shocks would be given to the anonymous receiver, for which the decider—not the receiver—would be paid.
Those who took citalopram were prepared to fork over an average equivalent of about 92 cents to avoid a shock and $1.12 to prevent harm to others, compared to 54 cents and 68 cents, respectively, from those in the placebo group. That suggests citalopram made participants more considerate of other people's pain. On the flip side, those who took levodopa were willing to pay 54 cents to prevent a shock to others or themselves. "The dopamine drug made people more selfish," a researcher tells the Guardian. "Most people show this pattern where they think it's worse to harm other people than to harm oneself. That's abolished by the drug." Another researcher says the experiment shows "how serotonin and dopamine affect people's willingness to harm others for personal gain" but raises "important ethical questions about the use of such drugs," per a press release. (Antidepressants may also change your feelings of love.)