Antidepressants, Parkinson’s Med May Affect Morality, Decision-Making

the Psychiatry Advisor take:

Giving mood-altering drugs to healthy people influences their willingness to tolerate harm against themselves and others, according to a study. The results, which have implications about morality and decision making, were published in the journal Current Biology.

The study included 175 participants, 89 of whom were given citalopram or placebo, and 86 of whom were given levodopa or placebo. Citalopram (Celexa) is a serotonin-boosting antidepressant, and levodopa is a dopamine-enhancing drug used in Parkinson’s disease. The researchers compared how much pain each participant was willing to anonymously inflict on themselves or other people in exchange for money.

Participants were paired into decision-makers and receivers. Decision-makers had the opportunity to exchange different amounts of money for different amounts of shocks to themselves or the receivers.

People who were given a placebo were willing to pay an average of 35 pence (54 cents) to prevent a shock to themselves and 44 pence (68 cents) to prevent a shock to the receivers. Participants randomized to citalopram were willing to pay an average of 60 pence (93 cents) to prevent a shock to themselves and 73 pence ($1.13) to prevent a shock to the receivers.

Participants randomized to levodopa were willing to pay an average of 35 pence (54 cents) to prevent a shock to themselves or the receivers. They were also less hesitant to shock others compared with those who received placebo.

The results indicate that increasing serotonin made participants more averse to harm, while more dopamine made participants more selfish.

"Our findings have implications for potential lines of treatment for antisocial behavior, as they help us to understand how serotonin and dopamine affect people's willingness to harm others for personal gain," said Molly Crockett, PhD, of Oxford University in England, said in a statement.

However, the researchers note that these results represent effects on healthy people. More research is needed to see how these drugs affect the decisions of people taking these drugs for medical purposes.