A new study concludes people who took a pill used to treat Parkinson’s disease were more generous and fair-minded.

Have a heart. Take a pill.

Researchers at the University of California, Berkeley, and the University of California, San Francisco, say a pill that alters a person’s brain chemistry can make them more compassionate toward others.

Scientists say the discovery might not only lead to ways to improve prosocial behavior, but it might also help doctors better understand the interaction between the brain chemical dopamine and certain mental illnesses, such as schizophrenia and addiction.

“Our study shows how studying basic scientific questions about human nature can, in fact, provide important insights into diagnosis and treatment of social dysfunctions,” said Ming Hsu, a co-principal investigator and assistant professor at Berkeley’s Haas School of Business, in a press statement.

Hsu’s researched was published in the journal Current Biology.

In the experiment, researchers studied 18 women and 17 men. The participants were given either a placebo or the drug tolcapone (Tasmar), which prolongs the effects of dopamine. The chemical dopamine, which we all make naturally, is associated with reward and motivation in the prefrontal cortex of the brain.

Tolcapone is an FDA-approved drug used to treat Parkinson’s disease, which leads to falling levels of dopamine in the brain, causing patients to lose muscle control. 

Neither the participants nor the researchers knew at the time of the study who got the real drug and who took the placebo.

After taking their pill, the volunteers on two separate visits played a simple economic game where they divided money between themselves and an anonymous partner.

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The researchers said participants who took the tolcapone divided the money in a fairer and more generous way than those who got the placebo.

“We typically think of fair-mindedness as a stable characteristic, part of one’s personality,” said Hsu. “Our study doesn’t reject this notion, but it does show how that trait can be systematically affected by targeting specific neurochemical pathways in the human brain.”

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The researchers said previous studies have shown people evaluate economic inequality in their prefrontal cortex. They said the study brings scientists closer to pinpointing how prosocial behaviors such as fairness get their start in the brain.

“We have taken an important step toward learning how our aversion to inequity is influenced by our brain chemistry,” said the study’s first author, Ignacio Sáez, a postdoctoral researcher at the Haas School of Business. “Studies in the past decade have shed light on the neural circuits that govern how we behave in social situations. What we show here is one brain ‘switch’ we can affect.”

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