Dysthymic disorder in adolescents with intellectual disability

The present report examines the clinical features of dysthymic disorder in a sample of adolescents with mild intellectual disability (ID). Frequency of symptoms, comorbidity, agreement between reports of subjects and parents, comparison between the frequency of depressive symptoms in subjects with ID and in two different groups of normal IQ dysthymic subjects (aged 7-11, 11 and 12-18 years) are described. The sample consisted of 12 subjects (age range = 12-25.6 years; mean age = 16.3 years) screened from unselected consecutively referred patients with mild ID. All the subjects were comprehensively diagnosed with a structured diagnostic interview, the Kiddie-Schedule for Affective Disorder and Schizophrenia (K-SADS), according to DSM-IV criteria. A symptomatic profile in the group with ID showed that intrapsychic and cognitive symptoms, such as depressed mood, irritability, pathological guilt and low self-image, were frequently reported in people with ID. Parents were less aware of depressed mood, but they reported high rates of low self-esteem; the agreement between the depressive reports of ID subjects and their parents was higher than in previous findings in normal IQ children. The symptomatic profile of subjects with ID was more comparable to that of prepubertal dysthymic children than that of dysthymic adolescents, but more significant are the analogies between dysthymic disorder in ID and normal IQ subjects. High rates of comorbidity with generalized anxiety disorder were evident in the group with ID. According to the present data, dysthymic disorder can be diagnosed in adolescents with mild ID. The K-SADS clinical interview seems to be a reliable instrument for the diagnosis and clinical definition of depressive symptomatology in this special population.