Adolescent Sex Linked to Adult Body, Mood Troubles in Animal Study

A new study suggests that sex during adolescence can have lasting negative effects on the body and mood well into adulthood, most likely because the activity occurs when the nervous system is still developing.

While the research used laboratory animals, the findings provide information that may be applicable to understanding human sexual development.

Researchers paired adult female hamsters with male hamsters when the males were 40 days old, the equivalent of a human’s mid-adolescence. They found that these male animals with an early-life sexual experience later showed more signs of depressive-like behaviors as well as lower body mass, smaller reproductive tissues and changes to cells in the brain than did hamsters that were first exposed to sex later in life or to no sex at all.

Among the cell changes observed in the animals that had sex during adolescence were higher levels of expression of a gene associated with inflammation in their brain tissue and less complex cellular structures in key signaling areas of the brain.

They also showed signs of a stronger immune response to a sensitivity test, suggesting their immune systems were in a heightened state of readiness even without the presence of infection – a potential sign of an autoimmune problem.

The combination of physiologic responses in adulthood don’t necessarily cause harm, but do suggest that sexual activity during the nervous system’s development might be interpreted by the body as a stressor, researchers say.

During adolescence the body a child has had for several years seems to become different and sometimes strange. This phase of development is referred to as puberty and involves rapid changes in the body, including sexual maturation. Bodies change, attitudes about self and others change, thinking abilities change, and interest in sexual activities changes as well. The good news is that puberty does not last forever—most people get through it by age 18.

“Having a sexual experience during this time point, early in life, is not without consequence,” said John Morris, a co-author of the study and a doctoral student in psychology at Ohio State University. “It could be affecting males’ susceptibility to symptoms of depression, and could also expose males to some increase in inflammation in adulthood.”

Morris presented the research Tuesday (11/15) at the Society for Neuroscience annual meeting in Washington, D.C. He conducted the study with Zachary Weil, research assistant professor, and Randy Nelson, professor and chair, both from Ohio State’s Department of Neuroscience.

Previous research has most often examined the effects of adolescent sex on young women, and for ethical reasons must be done in humans as retrospective explorations of behavior. The Ohio State scientists used hamsters, which have physiologic similarities to humans, to learn specifically how the body responds to sexual activity early in life.