A new study suggests that poor mental health and casual sex feed off each other in teens and young adults, with each one contributing to the other over time.
Researchers found that teens who showed depressive symptoms were more likely than others to engage in casual sex as young adults. In addition, those who engaged in casual sex were more likely to later seriously consider suicide.
"Several studies have found a link between poor mental health and casual sex, but the nature of that association has been unclear," said Sara Sandberg-Thoma, lead author of the study and a doctoral student in human sciences at The Ohio State University.
"There's always been a question about which one is the cause and which is the effect. This study provides evidence that poor mental health can lead to casual sex, but also that casual sex leads to additional declines in mental health."
Sandberg-Thoma conducted the study with Claire Kamp Dush, assistant professor of human sciences at Ohio State. The research was published online recently in the Journal of Sex Research and will appear in a future print edition.
One surprising finding was that the link between casual sex and mental health was the same for both men and women.
"That was unexpected because there is still this sexual double standard in society that says it is OK for men to have casual sexual relationships, but it is not OK for women," Kamp Dush said.
"But these results suggest that poor mental health and casual sex are linked, whether you're a man or a woman."
The study used data from the National Longitudinal Study of Adolescent Health. Adolescents from 80 high schools and 52 middle schools were interviewed when they were in grades 7 through 12 and then again when they were aged 18 to 26.
In all, this study involved about 10,000 people who were surveyed about their romantic relationship experiences across time, as well as depressive symptoms and thoughts of suicide.
Overall, 29 percent of the respondents reported engaging in any casual sexual relationship. These were defined as any relationship in which the participant reported he or she was "only having sex with partner" as opposed to dating. This included 33 percent of men and 24 percent of women.
The results showed that participants who reported serious thoughts of suicide or more depressive symptoms as teens were significantly more likely to report having casual sexual relationships when they were young adults.
Casual sex, in turn, was linked to further declines in mental health. Specifically, those who had casual sex in their late teens and early 20s were significantly more likely to have serious thoughts of suicide as young adults, results showed. In fact, each additional casual sex relationship increased the odds of suicidal thoughts by 18 percent.
However, casual sex in late teens and early 20s was not associated with changes in depression as a young adult.
The researchers are not sure why casual sex was linked to later serious consideration of suicide, but not depressive symptoms, in these participants. It may be that depressive symptoms fluctuate during adolescence and it is hard to capture an accurate reading when measured just twice, as in this study, Kamp Dush said.
But the findings suggest that both researchers and health professionals need to consider more than one measure of mental health.
"Just because a person does not indicate depressive symptoms in one survey is not always proof that he or she is doing OK," Kamp Dush said.
"We need to look at multiple indicators of mental health, including suicidal thoughts."
The results do point to a possible "cyclical pattern" in which poor mental health leads to casual sex, which leads to further declines in mental health, Sandberg-Thoma said.
"The goal should be to identify adolescents struggling with poor mental health so that we can intervene early before they engage in casual sexual relationships," she said.
Kamp Dush said casual sexual relationships may hurt the ability of young adults to develop committed relationships at an important time in their development.
"Young adulthood is a time when people begin to learn how to develop long-term, satisfying and intimate relationships," she said.