New research suggests medical cannabis may actually improve cognitive function in adults rather than impairing it.

The study published this week in the journal Frontiers in Pharmacology is thought to be the first of its kind to specifically examine how medical cannabis use impacts cognitive performance in adults.

To gauge such impacts, researchers from McLean Hospital, a psychiatric affiliate of Harvard Medical School, measured a small group of patients’ cognitive performance prior to starting medical marijuana, and again after three, six and 12 months of marijuana treatment.

The current study assesses the impacts of three months of medical cannabis treatment on 11 patients who have returned so far for their first follow-up after initiating treatment.

“After three months of medical marijuana treatment, patients actually performed better, in terms of their ability to perform certain cognitive tasks, specifically those mediated by the frontal cortex,” Staci Gruber, director of the Marijuana Investigations for Neuroscientific Discovery program at McLean Hospital, said in a statement.

Study participants also reported improvements in clinical conditions, sleep, overall health and decreased use of conventional pharmaceutical medications, particularly opiates.

“We saw a 42 percent reduction in opioid use,” Gruber said. “This is significant, particularly for those of us in Massachusetts and other areas of the country where the opioid epidemic is ravaging so many. This preliminary finding certainly warrants deeper and broader investigation.”

Despite a “growing body of evidence suggesting recreational marijuana adversely affects brain function, particularly during periods of developmental vulnerability such as adolescence,” researchers found no such adverse effects among study participants who used medical marijuana.

Gruber believes these findings may be due to the ages of participating patients, differences in the chemical compositions of various recreational and medical cannabis products, and the ways such products are used. Higher levels of the nonpsychoactive cannabinoid CBD, which is more typically found in medical cannabis products, may have something to do with it as well.

“While intriguing, these findings are preliminary and warrant further investigation at additional time points and in larger sample sizes,” the study research article explains.

The longitudinal study is slated to continue for at least two years. Gruber plans to further examine the impacts of individual cannabinoids and combinations of cannabinoids on various aspects of brain function and structure, and how these may translate to changes in cognition and mood.

“As a clinical researcher, I’m not interested in exploring only the good or the bad, I’m only interested in the truth,” Gruber said. “That’s what our patients and our recreational users have a right to know and a right to expect from us. People are going to use it. It’s up to us to figure out the very best and safest ways in which they can do that.”