About 20 percent of children ages 9–17 are estimated to have mental disorders with at least mild functional impairment, 6.2 percent of which have a mood disorder (Shaffer et al., 1996). Longitudinal data from New Zealand (Feehan et al., 1993) found a 21.5 percent prevalence rate of DSM-III disorders at age 15 and a 36 percent prevalence rate at age 18. The most prevalent conditions at age 15 were anxiety (8 percent) and conduct disorders (5 percent). At age 18, they were major depressive episode (17 percent), alcohol dependence (10 percent), and social phobia (11 percent). In the United States, depression is the strongest correlate of suicide for adolescent suicide victims and attempters (Brent et al., 1993; Shaffer, 1988), although some studies find conduct disorder more strongly associated with suicide attempts in adolescents (Borst and Noam, 1989). In four studies, between 40 and 53 percent of the youth suicides were diagnosed with a personality disorder (Brent et al., 1994; Lesage et al., 1994; Rich and Runeson, 1992; Rich et al., 1986). The prevalence of personality disorders in suicide appears to decline with age (Rich et al., 1986), perhaps due to a decreased population prevalence of personality disorders across the lifespan (Ames and Molinari, 1994; Cohen et al., 1994).
The nature and distribution, as well as symptom presentation, of mental disorders are somewhat different in children and youth as compared to adults, although the overall prevalence is comparable. Youth are more likely to exhibit irritability, acting out behaviors, and anger rather than exhibiting sad and depressed affect (APA, 1994). Bipolar disorder in youth often presents with symptoms typically diagnosed as conduct disorder and/or attention deficit disorder (Berenson, 1998; Mohr, 2001). It also may be that bipolar disorder in youth is frequently comorbid with these other disorders, complicating diagnosis and treatment (Berenson, 1998; Mohr, 2001).
Hopelessness, an important risk and predictive factor for adult suicide (see below), is also associated with suicidality in adolescents. Hopelessness predicts repeat suicide attempts and differentiates suicidal from non-suicidal psychiatrically disturbed youths (for reviews, see Brent et al., 1990; Weishaar and Beck, 1990). The severity of depression may be a stronger predictor of suicidality than hopelessness in younger populations (e.g., Asarnow et al., 1987; Cole, 1989; Goldston et al., 2001), which may reflect the time-course of cognitive development (c.f., Nolen-Hoeksema et al., 1992). On the other hand, positive expectations are one of the strongest predictors of resilient people from childhood through