Neurobiology of Teenage Suicide

About 30,000 persons die by suicide each year in the United States alone (Botsis et al., 1997). It is the second or third (depending on the age group and sex) most frequent cause of death for teenagers in the United States (CDC, 2011; Lowy et al., 1984; Moscicki et al., 1988). In 2006, the age-adjusted suicide rate among youth aged 10–19 years in the United States was 4.16 per 100,000. Among this population, the rate of suicide increases with age, and the suicide rate is substantially higher in boys than in girls—in boys between ages 18 and 19 years, the suicide rate is 15–20 per 100,000, and in girls, the rate is 3–4 per 100,000 (Bridge et al., 2006; CDC, 2011). In adults, suicidal behavior is a major symptom of depression and other psychiatric disorders, such as schizophrenia, alcoholism, and personality disorders. Besides psychiatric illnesses, other risk factors include a family history of suicide and a family history of psychiatric disorders and alcoholism, psychosocial stressors, impulsivity, and aggression (Joiner et al., 2005). Abnormalities in neurobiological mechanisms may also be a predisposing or risk factor (Mann et al., 1999; Underwood et al., 2004). Studies conducted on patients with suicidal behavior (Pandey et al., 1995) and on postmortem brain samples from suicide victims (Pandey et al., 2002a) strongly suggest that suicide is associated with neurobiological abnormalities. Although some progress has been made in elucidating the role of serotonin (5-hydroxytryptamine, 5HT) and other neurobiological mechanisms in adult suicide, the neurobiology of adolescent suicide is understudied. There is evidence to suggest that some factors associated with adolescent suicide may be different from adult suicide (Brent et al., 1999; Zalsman et al., 2008). Although the impulsive–aggressive behavior is a common risk factor for both adult and teenage suicide, aggression and impulsivity are traits highly related to suicidal behavior in adolescents (Apter et al., 1995). Higher levels of impulsive aggressiveness play a greater role in suicide among younger individuals with decreasing importance with increasing age (Brent et al., 1993). Brent et al. have also shown that adolescents with aggression and conduct disorders may be suicidal even in the absence of depression. Psychosocial factors associated with adolescent suicide, such as stress and contagion, bullying, and peer victimization (Brunstein et al., 2008; Bursztein and Apter, 2009; Klomek et al., 2008), may also be different. Alcohol and drug abuse contribute significantly to the risk of suicide in teenagers (Apter et al., 1990, 1995). Additional potential contributors to suicidal behavior in depressed adolescents are other early defined traits, such as temperament and emotional regulation. One study (Tamas et al., 2007) suggests that suicidal youths are characterized by high maladaptive regulatory responses and low adaptive emotional regulation responses to dysphoria. Since there are both similarities and differences in the risk factors for teenage and adult suicides, it is quite likely that the neurobiology of teenage suicide may be similar in some respects to adult suicide and different in others. The neurobiology of teenage suicide has been primarily studied by the group of Pandey and colleagues. In this chapter, we summarize these studies and have also discussed the similarities and differences in the findings between teenage and adult suicide victims. Since we also study the neurobiology of adult suicide, we compare these neurobiological findings with particular reference to our own findings and briefly to those reported in the literature.