Adolescent depressive disorder: a population-based study of ICD-10 symptoms

Objective: Earlier studies have suggested that symptoms of depressive disor der in adolescents may differ from those found in adults. Even so, diagnost ic criteria developed in adults have come to be widely applied to younger s ubjects. This study examines the frequency of ICD-10 symptoms in depressive disorder and their association with severity in a large community sample o f adolescents aged 15 to 18 years. Method: A six-wave prospective study of adolescent health and emotional wel lbeing in 2032 Australian secondary school students provided an opportunity to conduct a two-phase study of adolescent onset depression. A self-admini stered computerised form of the revised Clinical Interview Schedule (CIS-R) was used as a first phase diagnostic measure. Second phase assessment usin g the Composite International Diagnostic Interview (CIDI) allowed the delin eation of a group fulfilling criteria on both instruments. The ICD-10 sympt oms and severity profiles for depression were generated with standard algor ithms. Results: 1947 (95.8%) out of 2032 subjects in the designated sample complet ed phase 1 assessment at least once. Participation rates at phase 2 intervi ews were 93%. Over the 30-month study period 69 subjects (10 male, 59 femal e) fulfilled criteria for ICD-10 depressive episodes on both the CIS-R and CIDI. Thirty-one per cent (n = 21) had experienced a severe episode, 46% (n = 32) moderate and 23% (n = 16) mild episodes. Loss of interest and pleasu re, decreased energy and fatigue, sleep disturbance, suicidal ideation and diminished concentration most clearly distinguished adolescents with depres sive disorder from controls. Self-reproach and guilt, psychomotor agitation and/or retardation and appetite disturbance with weight change showed the clearest increase in frequency with increasing severity of episode. The som atic syndrome was reported by close to one in three of those with a severe depressive episode, but was uncommon in those with mild and moderate episod es. Conclusions: The ICD-10 diagnostic criteria are applicable to depressive di sorder in older adolescents. With the exception of depressed mood, found in one in five non-cases, all other symptoms were common in cases and uncommo n in non-cases. Practitioner awareness of symptoms indicating the presence and severity of disorder should enhance early identification and choice of treatment in adolescent depression.