Despite media and popular stereotypes of moody, apathetic teen-agers, most adolescents are well-adjusted and productive. Nevertheless, many adolescents experience depressive symptoms, and some have episodes beyond transient feelings and normal development. Adolescence is a key period when many mental health disorders--including depression, dysthymia and other comorbid conditions--are often recognized. Although depressive disorders are relatively rare during childhood, by adolescence the prevalence is estimated between 2% to 8% (Burke et al., 1990; Costello et al., 1996; Lewinsohn et al., 1998; Lewinsohn et al., 1994). During early adolescence, a striking gender difference also emerges, with females two to three times more likely to report depression than males (Fleming and Offord, 1990). By 21 years of age, the cumulative prevalence of an episode of major depressive disorder has been reported to be 10% to 20%, with rates reported as high as 35% in young women (Lewinsohn and Clarke, 1999). Depression is associated with suicide, school failure and significant long-term morbidity. The U.S. Surgeon General, the World Health Organization (WHO) and other groups have identified depression as a major public health issue that has tremendous impact on productivity and economics in the United States and worldwide (Murray and Lopez, 1997). Despite the high prevalence and morbidity, growing research and continued innovations can provide great potential for prevention, early intervention and long-term treatment to significantly reduce morbidity and mortality.
Understanding the epidemiology and natural course of depressive symptoms and disorders in adolescents is important for clinical care, quality-improvement initiatives and research design. This knowledge can aid strategies to select high-risk populations for targeted screening or efforts to identify unrecognized and untreated depression. Treatment decisions and, therefore, outcomes may be improved with a better understanding of which teens are more likely to have persistent and more severe depressive episodes. In turn, by understanding the different clinical courses that can be expected, long-term care and the transition to adulthood may be improved as well.
Cultural and Racial Factors
Beyond well-recognized effects of age and gender, a growing body of literature has noted other differences in adolescent expression of depressive disorders. Race, ethnicity, sociodemographics, culture and religion have all been associated with depressive disorders (Garrison et al., 1990; Garrison et al., 1989; Goodman, 1999; Lewinsohn et al., 1998). For example, according to a Surgeon General report (U.S. Department of Health and Human Services, 2001), Asian-Americans tend to suppress affect and avoid expression of upsetting thoughts; African-Americans tend to confront personal problems instead of using avoidance techniques; and Thai Buddhist children exhibit relatively more social restraint. Further, the DSM-IV now recognizes distinct "culture-bound syndromes," and the different expression of disorders--like depression--common to all cultures has been described for several different groups. Clearly, mistrust and stigma of treatment also have deep historical roots for many races and cultures.
The Surgeon General's and government's initiatives have highlighted racial disparities in the access, delivery and receipt of mental health services (Satcher, 2001). These efforts focus on several levels--the health care system, providers, communities, families and patients--to improve mental health care, since the effects of race can impact health system outreach, provider communication, community support, family stigmatization and patient care-seeking.
International comparisons further reflect the clear differences among mental health and suicide rates of adolescents of different cultures and nations (Crijnen et al., 1997; Diekstra and Garnefski, 1995). A WHO study showed that, in 1997-1998, 11-year-old children in the United States had the highest levels of depressive symptoms compared with 28 other developed nations; 38% of females and 32% of males reported "feeling low" at least once a week during the last six months. Rates for those aged 15 showed weekly depressive symptoms in 49% of adolescent females and 34% of adolescent males (Scheidt et al., 2000). In contrast, Austrian teens reported the lowest level of weekly depressive symptoms (Figure) and Canadian youth fell in the middle of the teens worldwide reporting. In the same study, researchers found that U.S. youth were leaders in report of stomachaches, headaches and use of medications, and the United States was among the top four for seven of the nine health symptoms studied. Teens in the United States were more likely than respondents from other nations to report difficulty talking with their mothers (Settertobulte, 2000) and pressure by school work, and they were less likely to report that their fellow students were often kind and helpful (Samdal and Dr, 2000).
Another interesting report from comparisons of international data shows that depression and mental health problems may be increasing. The overall population prevalence of depression by birth cohort showed an increase in depression during subsequent generations over the last century (Cross-National Collaborative Group, 1992). Studies of worldwide trends show that depression may also have an earlier onset in recent years (Bland, 1997). The United States has an average age of onset in the mid-20s, which is younger than in most other countries studied (Bland, 1997). These trends were noted before the current environment of terrorism, and rates of stress and mental disorders may be even higher now in our unstable world.
The manner in which all of these complex factors interact makes any single clear answer to these national disparities elusive. Some of the potential interacting factors that contribute to higher rates of depressive symptoms among U.S. youth include violence, television/media, family structure and several other hypothesized causes. Beyond psychosocial and behavioral factors, emerging research is looking at genetic differences in neurotransmitter receptors and neuroanatomic variants. Although these findings may prove valuable in identifying patients who respond to treatment, most likely the research will not totally explain the variation among nations. Climate and the physical environment have even been shown to be associated with different rates of depression. Other factors such as access to medical care, school services, insurance barriers, and organization of health care and social services in different areas and countries may also account for some differences--especially when considering diagnosis and treatment rates. The same factors of society, community, family and peers that may be associated with higher rates of depression in some countries may conversely create strength and resiliency and serve as protective factors in other areas. It is also important to note that many studies report associations between factors, but delineating clear causal relationships is more challenging.