PSYCHIATRIC-DISORDER IN A BIRTH COHORT OF YOUNG-ADULTS - PREVALENCE, COMORBIDITY, CLINICAL-SIGNIFICANCE, AND NEW CASE INCIDENCE FROM AGES 11 TO 21

Mental health data were gathered at ages 11, 13, 15, 18, and 21 in an epidemiological sample using standardized diagnostic assessments. Prev alence of Diagnostic and Statistical Manual of Mental Disorders (3rd e d. revised; American Psychiatric Association, 1987) mental disorders i ncreased longitudinally from late childhood (18%) through mid- (22%) t o late-adolescence (41%)and young adulthood (40%). Nearly half of age- 21 cases had comorbid diagnoses; and comorbidity was associated with s everity of impairment. The incidence of cases with adult onset was onl y 10.6%: 73.8% of adults diagnosed at age 21 had a developmental histo ry of mental disorder. Relative to new cases, those with developmental histories were more severely impaired and more likely to have comorbi d diagnoses. The high prevalence rate and significant impairment assoc iated with a diagnosis of mental disorder suggests that treatment reso urces need to target the young adult sector of the population. The low new-case incidence in young adulthood, however,suggests that primary prevention and etiological research efforts need to target children an d adolescents.