A new study has suggested, Sex during preadulthood can have lasting negative effects on the body and mood well into adulthood, most likely because the nervous system is in its developing phase during this age.

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 behaviours 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 signalling 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 researchers said, 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.

John Morris, a co-author of the study and a doctoral student in psychology at Ohio State University quoted “Having a sexual experience during this time point, early in life, is not without consequence,”

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

John Morris presented the research at the Society for Neuroscience annual meeting in Washington, D.C