Adolescents who engage in sex and drug behaviors are at risk for future depression, reported Denise D. Hallfors, Ph.D., and her colleagues at the University of North Carolina at Chapel Hill.
In their study, the association existed among youth of both sexes, but adolescent girls appear to be especially vulnerable to subsequent depression risk.
Although previous studies have associated adolescent depression with sex and drug use, the current study is among the first to provide insight into the causal relationship between the risky behaviors and depression, the authors wrote.
The findings appear to reject the frequent hypothesis that adolescents use sex and drugs to self-medicate depression, Dr. Hallfors and her associates said.
Using data from the National Longitudinal Study of Adolescent Health (Add Health)—a nationally representative sample of more than 13,000 7th- to 11th-grade adolescents who were first interviewed in 1995 and reinterviewed in 1996—investigators examined whether gender-specific patterns of substance use and sexual behavior predicted depression or whether depression predicted the gender-specific patterns of these risky behaviors (Am. J. Prev. Med. 2005;29:163–70).
In addition to sociodemographic measures, study data included self-reported information on adolescent risk behaviors, perceptions of physical maturity, and depression, measured using a version of the Center for Epidemiological Studies-Depression Scale (CES-D) modified for the study population to maximize sensitivity and specificity for detecting major depressive disorder in adolescents.
Compared with those adolescents who reported abstaining from risk behaviors in the initial interview, adolescents who engaged in risk behaviors were significantly more likely to meet the criteria for depression at the time of the second interview.
In particular, girls who fell into “experimental behavior” clusters at the initial interview—self-reported drinkers and those who reported experimenting with substances and sex—had a two- to threefold increase in depression compared with girls who abstained from such activities.
In contrast, boys in the experimental behavior clusters were no more depressed than were boys who abstained.
Similarly, girls in the high-risk behavior clusters—those with multiple sex partners and intravenous drug use—were significantly more likely than were abstainers to be depressed, while similar behavior patterns were not predictive of depression among boys.
In boys, binge drinking and frequent marijuana use were associated with a fourfold increase in depression compared with abstainers, while these patterns did not predict depression among girls.
In girls, depression at the first interview did not increase the likelihood of engaging in experimental behavior patterns, and it lowered the likelihood of engaging in high-risk behaviors.
In boys, depression was not predictive of engaging in either experimental or high-risk behaviors.
For girls who reported experimental behavior at baseline, depression did not predict further experimental behaviors, but it did predict movement to a high-risk behavior cluster. In boys who engaged in experimental behaviors, depression did not increase the likelihood of further experimentation or high-risk behaviors.
Given the gender-specific patterns in the relationship between risk behaviors and depression, screening and preventive interventions should be designed accordingly, the investigators said.
“Our findings indicate that patterns of substance abuse, especially binge drinking and frequent marijuana use, increase the likelihood of depression in boys by more than fourfold. Thus, boys who are heavy users should be counseled to reduce or stop use, and screened for depression,” they suggested. Boys who present with depression should be screened for substance abuse and addiction, which, if present, should be treated aggressively.
Among adolescent girls, those who engage in substance use or sex behaviors should be screened for depression “and provided with anticipatory guidance about the mental health risks of these behaviors,” the investigators said.
Treatment for adolescent girls with depression should include an assessment of risk behaviors, as well as appropriate substance use and sexual decision-making messages and counseling.
“Management plans for both boys and girls may also need to address issues related to sexually transmitted infections, HIV, unintended pregnancy, injury prevention, and depression and/or suicide risk,” Dr. Hallfors and her associates said.
Although temporal ordering of risky behavior and depression seen in this study suggests a cause-and-effect relationship, “these analyses cannot rule out unidentified predisposing factors that may cause both,” they pointed out, noting that more research is needed to identify the mechanisms of risk as well as to determine whether efforts to reduce risk-taking behaviors will have an impact on later depression risk.