A new study suggests teen sex can have lasting effects on mental health — at least in male hamsters.

Researchers from Ohio State University found that male hamsters that mated when they were 40 days old (the hamster equivalent of adolescence) showed symptoms of depression later on compared to their abstaining littermates.

“Having a sexual experience during this time point, early in life, is not without consequence,” John Morris, a doctoral student in psychology and co-author of the study presented at the Society for Neuroscience meeting in November.

Adult 120-day-old hamsters that had teen sex were less enthusiastic about swimming in a shallow pool and exploring a maze, symptoms of depression and anxiety that were not seen in virgin hamsters. They also had higher brain levels of a gene involved in inflammation, a change that might interfere with the brain’s normal development.

“There is a time in nervous system development when things are changing very rapidly, and part of those changes are preparations for adult reproductive behaviors and physiology,” Zachary Weil, assistant professor of Neuroscience at OSU, said in a statement. “There is a possibility that environmental experiences and signals could have amplified effects if they occur before the nervous system has settled down into adulthood.”

Nearly half of U.S. high school students have had sex, according to a 2009 survey by the Centers for Disease Control and Prevention, and 14 percent have had sex with four or more people. An estimated one in 10 adults report suffering from depression.

The researchers suggest sexual activity might serve as a stressor during development.

“It could be affecting males’ susceptibility to symptoms of depression, and could also expose males to some increase in inflammation in adulthood,” said Morris.