SAN FRANCISCO (CBS SF) – A drug that is used to treat Parkinson’s disease has also been found to make patients less tolerant of inequality and engage in more equitable behaviors.

According to a statement from the University of California, researchers at UC Berkeley and UCSF studied the effects of tolcapone. The drug prolongs the effects of dopamine, which is a chemical associated with reward and motivation in the prefrontal cortex.

Researchers performed a double-blind study of 35 people, where they received either tolcapone or a placebo on two separate visits. Participants then played a simple game where they divided money between themselves and a recipient they didn’t know.

The researchers found those with tolcapone divided the money in a “fairer, more egalitarian way,” the university statement read.

“We have taken an important step toward learning how our aversion to inequity is influenced by our brain chemistry,” said Ignacio Saez of UC Berkeley’s Haas School of Business, the study’s first author.

Researchers hope that the study will eventually lead to a better understanding of mental illnesses such as schizophrenia or addiction, possibly leading to ways to diagnose or treat such disorders.