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Many adolescents experience depressive symptoms and some have episodes that go beyond transient feelings. Risk factors and predictive strategies are thwarted by the power of individual differences. Communicating with patient families; using the available innovative pharmacological, diagnostic and behavioral tools; and individualizing treatment approaches can improve outcomes.
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.
Before we speculate further on international differences, we must also consider how expression of opinions and test-taking characteristics affect U.S. teens' responses to questionnaires, interviews and scales and in clinical histories. Communications of feelings, coping styles and other characteristics may vary in different nations and among adolescents. Many screening tests and measures of acute depressive symptoms (used during the last week in the WHO study) may not be good proxies for actual depressive disorders. Reports of depressive symptoms may reflect variations in stigmatization of mental disorders and concepts of health and well-being. Depression has different manifestations in children than it does in adults, and assessment scales often developed for adults tend to overestimate depression scores when applied to youth (Costello and Angold, 1988; Roberts et al., 1991).
Finally, it is important to consider what significance subclinical or minor depression has in terms of long-term outcomes. Most studies are conducted in patients with severe impairment and recruitment is often in clinical and referred samples. We are just learning to appreciate the dimensionality of depressive disorders--that it is most likely not a dichotomous yes/no, on/off proposition.
Course of Illness
Depressive symptoms must also be viewed in the long-term perspective. Analysis of data from the National Longitudinal Study of Adolescent Health--a representative survey of U.S. adolescents in grades 7 through 12 conducted in the school and home in the mid-90s (Bearman et al., 1997)--shows the difficulties of predicting the course of depressive symptoms (Rushton et al., 2002). Students completed a version of the Center for Epidemiological Studies Depression (CES-D) Scale at the beginning of the study and one year later (Rushton et al., 2002). The majority of adolescents with minimal depressive symptoms (CES-D <16) at baseline continued to maintain similar CES-D scores a year later--only 3% of the group with minimal depressive symptoms developed moderate/severe depressive symptoms at one-year follow-up. For adolescents who were depressed at baseline, however, predicting persistent depressive features and resolution of symptoms proved very challenging. Many adolescents with moderate/severe symptoms reported a similar level of depression a year later, but more than half of the adolescents with moderate/severe depressive symptoms at baseline reported significant reduction on follow-up. Therefore, a negative screen on the CES-D or another evaluation of depressive symptoms may provide reassurance and place adolescents at low risk for future depressive symptoms. Adolescents with depressive symptoms may require ongoing evaluation though, since the course of their symptomatology can be quite variable.
In other analyses from our study, gender was the only sociodemographic variable consistently associated both with higher prevalence of depressive symptoms at baseline and follow-up.
Race, age and socioeconomic status were associated with higher baseline CES-D scores but did not predict greater likelihood of persistently elevated CES-D scores in longitudinal analysis. Other factors of adolescent self-esteem, resiliency, family and social support were not significantly associated with depressive symptoms.
Even with some knowledge of epidemiology, individual differences can be powerful and may limit the usefulness of risk factors and prediction strategies. We cannot forget the individual patient, comorbid conditions, and the family and social context. Depression is often a chronic, relapsing and recurrent disorder that must be approached with vigilance--no matter where an adolescent resides or their nationality, culture or race.
Yet, we cannot ignore the potential issues and comments on our society and modern life in the United States that are raised by reports that up to half of U.S. adolescents exhibit depressive symptoms. We must monitor rates of depression, particularly in this vulnerable group as they make their transition to adulthood; and we must keep an eye on prevention and early intervention before higher costs, morbidity and mortality are realized in later years. We must maintain a global perspective to work together and borrow from each other's successes in facing this important part of adolescents' lives. Finally, we cannot overlook the importance of communicating with each family and patient as we attempt to improve care of this complex chronic disorder and distinguish symptoms from disease.
Given the recent attention of genetics, neuroimaging, pharmacotherapy, public health and improved counseling techniques, we have multiple opportunities to improve care and impact entire nations, populations and individuals. Improvements may be realized through multiple approaches--targeted screening, probing with open communication and maintaining a high index of suspicion of possible depression in teens with school, family and/or social problems. Most important given the complex chronic course of depressive disorders and high occurrence of comorbid conditions, the first step may be to more effectively treat adolescents who are diagnosed with depression. The health care system must use innovations in information systems along with culturally sensitive, community-centered outreach initiatives to provide the long-term care and follow-up needed to prevent relapse and recurrence. Although national characteristics, cultural norms and other high-risk groups may inform the process and broaden research strategies, ultimately, clinical management must be individualized to the patient.
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