Common depression medication could send your moral compass spinning, says a new study on serotonin and harmful behaviors
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Drugs that alter brain chemistry, including antidepressants and anti-psychotics, are the most commonly prescribed medications in America after blood pressure and diabetes meds. But despite the fact that one in four women will take an antidepressant at some point in their lives, relatively little is known about the medications' side effects, especially how changing our brain chemicals changes who we are.

However, according to a new study published in the journal of Current Biology, drugs that mess with your mind may also be messing with your morals.

Oxford researchers asked 175 healthy adults to take a prescription that would either increase their serotonin (Citalopram, an antidepressant) or their dopamine (Levodopa, a medication used for treating Parkinson's)-the two main neurotransmitters in the brain primarily responsible for mood. The subjects were then put into pairs where one person was paid to decide whether they would harm themselves or harm the other person using electrical shocks. The "decider" was paid per shock so the more shocks they administered, the more they got paid.

It's actually a pretty ingenious study. "An aversion to harming others is a core component of human morality and is disturbed in [some mentally ill people]," wrote the researchers, who said they were looking to see whether or not one of the medications' side effects would be a change in this critical part of our humanity.

What they found could impact how doctors prescribe these common medications: Compared to the placebo group, people with more serotonin were less likely to harm either themselves or others and had an increased sense of altruism, meaning that they'd pay to shock themselves before shocking their partner. On the other hand, those with more dopamine were less altruistic and less likely to sacrifice themselves to protect their partner than the non-medicated group, meaning they'd prefer to be paid money to shock other people. In addition, the serotonin group thought longer about their decisions to harm someone else than the dopamine group did. (Find out more about The Dark Side of Antidepressants.)

Because the drugs didn't effect any other aspect of the decision making process, like perception of pain or loss aversion, the scientists concluded that the increase in the brain chemicals was solely responsible for the change in how the people made moral decisions. Not only does this show what a crucial role neurotransmitters play in shaping our personalities, but it shows how medication can be used to help people who may be missing the kindness chip. (In the meantime, find out 3 Ways to Be a Better Decision Maker.)

One problem the study didn't address, though, was how these medications affect the moral reasoning skills of people who are already sick with depression or other mental illness. Since they only looked at how healthy people were effected, the results could be much different on people who are already critically low in serotonin or dopamine.

While all this is interesting, the doctors cautioned patients not to stop taking their medication, but to use this information in talking with their own doctors about which medication is right for them.