This study compares DSM-IV symptoms in children (ages 6 to 12 years) with pervasive developmental disorder (PDD), clinic controls, and community-based samples. Parents/teachers completed the Child Symptom Inventory-4 for four samples: PDD (N = 284/284) and non-PDD psychiatric clinic referrals (N = 189/181) and pupils in regular (N = 385/404) and special (N = 61/60) education classes. The PDD group received higher symptom severity ratings than the regular education group, but was similar to the non-PDD clinic sample. Screening prevalence rates were highest for ADHD, ODD, and generalized anxiety disorder. PDD subtypes exhibited differentially higher rates of psychiatric symptoms. The magnitude of rater and gender differences in symptom severity ratings was modest. Clinic-referred children with PDD exhibit a pattern of psychiatric symptoms highly similar to nonPDD clinic referrals. Although much additional research is needed on comorbidity, these symptoms have important treatment implications.

Preschoolers with PDD exhibit more severe DSM-IV psychiatric symptoms than children in regular and special early childhood programs, and to some extent nonPDD psychiatric referrals. The concept of comorbidity warrants further exploration, as does informant-specific syndromes as validators of diagnostic constructs.

Anxiety appears to be a clinically important concern in many children with PDD. Similarities in anxiety symptom presentation and their association with psychotic symptoms in both children with and without PDD support the possibility of: (1) psychiatric comorbidity in the former; (2) at least some overlap in causal mechanisms for anxiety and psychotic symptoms in both PDD and non-PDD children; and (3) a unique diagnostic entity comprised of PDD, anxiety, and psychotic symptoms. Lastly, clinicians should seriously consider dual diagnoses in children with PDD.

Findings support the notion that ADHD may be a clinically meaningful syndrome in children with PDD.

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