Beta-adrenergic-blocking agents, commonly known as beta-blockers, are well-known heart drugs. They are often prescribed to treat cardiovascular conditions and acute cardiac events. They work mainly by blocking the action of hormones like adrenaline and slowing down the heart.

It appears that the usefulness of beta-blockers may extend to emotional issues as well. They have been used to treat anxiety and, more recently, they are being looked at as treatments for emotional and behavioral issues such as clinical depression and aggression.

The findings of studies about their use for these conditions have been conflicting, however.

To get a clearer picture of the potential mental health effects of beta-blockers, an international team led by researchers from the U.K. and Sweden analyzed data from more than 1.4 million people who were prescribed beta-blockers over an eight-year period. Using a within-individual design, records from periods when participants were taking beta-blockers were compared to records from periods when they were not taking the medication.

Beta-blocker use was linked with a 13 percent lower risk of being charged with a violent crime.

Although no consistent association was found between beta-blocker use and psychiatric outcomes, beta-blocker use was associated with a 13 percent lower risk of being charged with a violent crime. The researchers concluded that to better understand the possible role of beta-blockers for managing aggressive or violent behavior, more studies are needed, particularly large, randomized trials.

“Repurposing the use of β-blockers to manage violence and aggression could improve patient outcomes,” Seena Fazel, corresponding author on the study and a professor of forensic psychiatry at the University of Oxford, said in a statement.

The findings of past studies suggest an association between severe cardiac events and an increased risk of depression and suicide. The results of the current study suggest that psychological stress and other disabilities associated with major cardiac conditions increase the risk of psychiatric events, not treatment with beta-blockers. In secondary analyses, risk of hospitalization for major depressive disorder was lower during beta-blocker treatment.

The picture remains mixed. Beta-blockers have been linked to an increased risk of suicidal behavior, but study findings about this risk are inconclusive. Participants in the current research had an eight percent lower risk of psychiatric hospitalization, but an eight percent higher risk of being treated for suicidal behavior. These associations varied according to psychiatric diagnosis, past psychiatric conditions and the cardiac diagnosis for which the beta-blockers were prescribed. As the researchers point out, more studies examining the association of beta-blockers for cardiac patients and those prescribed to treat psychiatric and behavioral symptoms will be needed.

The study is published in PLOS Medicine.