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Objective: Autism spectrum disorders (ASD) are defined in terms of abnormalities in social and communication development in the presence of marked repetitive behavior and narrow interests. Patients with Asperger syndrome, as defined in the DSM IV, suffer from autistic social dysfunction but without mental retardation or language delay. Pervasive developmental disorder-not otherwise specified (PDDNOS), is reserved for patients who are within the autistic spectrum but do not meet the threshold for any of the named disorders. Comorbid symptoms and disorders require considerable attention and become a focus for intervention and medical treatment. In this study, we aimed to investigate comorbid psychiatric disorders in a large sample of children and adolescents diagnosed with ASD.
Methods: In one-year period, all children and adolescents diagnosed with ASD (n:258) were included. All diagnostic interviews were made by the same child psychiatry specialist (first author). The sample is divided into three subgroups (Autism n:111, PDD-NOS n:125, Asperger n:22) and comorbidity rates were also assessed according to these subgroups and gender.
Results: The children were 16 months-18 year-old (Mean: 6.3±3.9 years), 90.3% were 12 years-old or younger, and 80.2% were boys. In the whole group, 74.4% (male:75.4%; female: 70.6%) (Autism: 75.7%, Asperger: 86.4%, PDD-NOS: 71.2%) had at least one comorbid psychiatric diagnosis (excluding mental retardation). Most common disorders were found to be Attention deficit hyperactivity disorder (ADHD) (56.2%), anxiety disorders (21.7%), mood disorders (8.1%), learning disorders (4.2%), and tic disorders (3.8%). While mood disorders were more in autism (14.4%) and Asperger (9.0%) groups, tic disorders (22.7%) and anxiety disorders (31.8%) were significantly more in Asperger group. All learning disorder and tic disorder cases were male. While anxiety disorders were more common in female ASD patients (27.4% vs. 20.2%), ADHD was more common in male patients (57.9% vs. 49.0%).
Conclusion: The results of this study reveal that most of the patients with ASD had comorbid psychiatric disorders and the rates differed between gender and ASD subtypes. In the previous comorbidity studies, nearly seventy percent of participants had at least one comorbid disorder and 40% had two or more. The most common diagnoses were anxiety disorder (41-45%), ADHD (28-31%), and oppositional defiant disorder (7-28%). Obsessive–compulsive disorder was more common in older children, and oppositional defiant disorder/ conduct disorder more prevalent in PDD-NOS.