According to the literature psychiatric illnesses decrease the quality of life (QL) of children and adolescents. There is no data, however, about the differential effect of psychiatric comorbidity on QL. We hypothesized that 1. any comorbidity would decrease the QL of depressed children and 2. attention deficit-hiperactivity disorder (ADHD) would have a more negative effect on the QL of depressed children than other illnesses.

The sample consisted of 483 children diagnosed with major depression (MDD) (247 boys, mean age: 11.88 years, sd: 2,47). We compared 3 groups: 1. MDD without comorbidity (N=147), 2. MDD with comorbidity (no ADHD) (N=249), 3. MDD with ADHD with/without other comorbidity (N=87). Diagnoses were determined by semi-structured interview, quality of life was measured by self-report and parental report. Groups were compared by ANOVA, post hoc comparisons were done in cases of significant differences.

The MDD with ADHD group differed from the others in gender distribution, younger age at onset of depression, more frequent hospitalization and/or outpatient treatment. Child reported QL was not different among the groups. Parent reported QL was the highest in the MDD without comorbidity group, somewhat decreased in the MDD with comorbidity group and lowest in the MDD and ADHD group.

ADHD worsens the course of MDD in children and adolescents. Quality of life of depressed children decreases further by additional comorbidity, but ADHD has the most negative effect in parents' opinion. It is important to ask both parent and child in examining QL of children.