Risk Behaviors

Acquired immunodeficiency syndrome (AIDS) is a significant threat to youth and young adults. It is the seventh leading cause of death among U.S. youth aged fifteen to twenty-four. More than 126,000 cases of AIDS among individuals ages twenty to twenty-nine had been diagnosed in the U.S. through June 2000. Given the long latency period between infection and symptoms, most of these individuals were infected as adolescents. Estimates of human immunodeficiency virus (HIV) among adolescents range from 112,000 to 250,000 in the United States, although actual prevalence is not known because representative data are not available. Estimates of HIV incidence in the early twenty-first century suggest that at least 50 percent of the 40,000 new infections in the United States each year are among individuals under twenty-five years old, and 25 percent are among persons aged twenty-one or younger.

HIV Transmission

The majority of HIV infections among adolescents are contracted through sexual activity. Among HIV positive thirteen to nineteen year-old females who had not developed AIDS, 49 percent of the cases were associated with exposure through sexual contact, 7 percent through injection drug use, 1 percent through blood exposure, and 43 percent through a risk not reported or identified. Among males in the same age group, 50 percent were associated with male to male sex, 5 percent with injection drug use, 5 percent with both male to male sex and injection drug use, 5 percent with hemophilia or coagulation disorder, 7 percent with heterosexual exposure, 1 percent with blood exposure, and 28 percent with an unreported or unidentified risk.

Many adolescents are sexually experienced, but the extent of experience and risk varies for different groups of adolescents. Youth Risk Behavior Survey (YRBS) data indicate that about half of all high school students report having engaged in intercourse at least once. Almost 10 percent of youth were younger than age thirteen at first sexual intercourse, and by twelfth grade, 65 percent of students have become sexually active. Sexual risk increases with the number of partners and the failure to use condoms. In the YRBS data, about 16 percent of high school students report having had sex with four or more partners; 48 percent of adolescent African-American males report four or more sexual partners. Forty-two percent of sexually active respondents did not use a condom at last intercourse.

The presence of other sexually transmitted infections (STIs) can also facilitate HIV transmission. Adolescents and young adults are physiologically and behaviorally at higher risk for acquiring STIs. An estimated three million cases of STIs other than HIV are acquired each year among persons between ten and nineteen years old. Youth under the age of twenty-five account for two-thirds of the total number of cases of STIs diagnosed annually. Rates of chlamydia, gonorrhea, and human papillomavirus are particularly high among sexually active female teens. An individual's risk is affected by STI prevalence among the pool of potential sex partners. African-American and Hispanic teens, for example, are disproportionately overrepresented among AIDS cases and cases of other STIs. Given that sexual networks tend to be homogeneous by race, these youth are more likely to face greater prevalence of HIV among their sex partners.

Drug use also places young people at risk for HIV. The most direct route is through sharing needles. Addicts may engage in sex with multiple partners to obtain drugs or money to buy drugs, and may thus increase the spread of infection to otherwise low-risk individuals. Non-injected drugs may also reduce inhibitions, influencing the individual to engage in risky sexual activity. Studies show that there are positive relationships between substance use and various facets of sexual behavior, such as timing of initiation, frequency, persistence, and risk taking, for both adolescents and young adults. However, findings regarding this pathway are mixed and may vary by race/ethnicity. For example, the link between substance use and sexual activity may be less strong among African Americans. Alcohol consumption has been linked to sexual risk taking among white adolescents, but a more recent study found that young women's condom use patterns were not linked to pre-coital substance use.

Pathways to HIV Prevention

Longitudinal studies that follow high-risk youth into adulthood provide a way for researchers to understand the developmental pathways of problem behavior. Greater involvement with problem behavior as a youth is predictive of greater involvement in young adulthood. However, problem behavior in the teen years does not necessarily lead to poor adult outcomes. For most adolescents, drug use and sexual activity reflect behavior that is experimental and socially normative. Longitudinal studies have shown that a "maturing out" process typically occurs, particularly if the individual is embedded in conventional institutions such as marriage.

Although most adolescents will grow out of many risk behaviors, prevention efforts are needed to reduce the risk of HIV infection during adolescence. As has been found with other risk behaviors, studies have demonstrated that knowledge about risk is not sufficient for the prevention of HIV risk behavior. This is not really surprising, given the variety of individual and contextual factors that contribute to motivation and the persistence of risk behaviors into young adulthood. For example, substance abuse, suicidality, and depression in adolescence are strong predictors of increasing or maintaining HIV high risk behaviors in young adulthood. Other contributing factors are problems in relationships with parents, friends' misbehaviors, stressful events, and neighborhood violence and unemployment.

Given the complexity of factors that contribute to risk behavior, prevention efforts that focus exclusively on knowledge are unlikely to be successful. However, there are effective school-based HIV prevention programs, which typically rely on principles of Social Cognitive (Learning) Theory. These principles include the use of experiential activities that allow for the modeling and practicing of skills, and the reinforcement of group norms against unprotected sex. A focus on reducing sexual risk behaviors and the use of trained motivated teachers enhance program effectiveness. However, adolescents live and learn in a variety of social contexts, and it is important to expand the scope of HIV prevention to include contextual interventions. For example, consistent adult monitoring can reduce opportunities for risky behaviors, and religious involvement protects adolescents from premature sex and drug use behaviors. Although they are currently very limited, school-based or school-linked clinic services, such as condom distribution and STI diagnosis and treatment, can be another important strategy for prevention.