Rates of Psychiatric Comorbidity in Children with High Functioning Autism and Asperger's Syndrome

Background:

In addition to the diagnostic features of qualitative impairments in reciprocal socialization, communication and restricted/repetitive behavior, children with autism are vulnerable to comorbid conditions, especially other psychiatric disorders. These may further complicate the developmental trajectory and affect their functional outcomes. In spite of some recent efforts to characterize these comorbid disorders, there is a paucity of empirical investigations into the prevalence of the comorbid psychopathology and the nature of  the relationship of the DSM-IV psychiatric disorders to the core features of Autism Spectrum Disorders (ASD).

Objectives:

To examine the  rate of psychiatric comorbidity in children with high functioning autism (HFA) or Asperger’s syndrome (ASP).

Methods:

The presence of comorbid psychiatric diagnoses was examined in a cohort of 71 children (10 girls and 61 boys) with HFA (n=35) or ASP (n=36) , aged 8 through 12 years (mean age 9.9 years +/-1.58 years; mean FSIQ 99 +/- 15.87).  These subjects were recruited as part of an ongoing neuroimaging and behavioral study; children with a history of epilepsy or known genetic diagnosis were excluded from participation.  Diagnosis was confirmed with ADI-R and ADOS-G. A computerized parent interview, the Diagnostic Interview for Children and Adolescents-IV –Parent version (DICA-IV) was used to examine for the presence of psychiatric comorbidity.

Results:

Attention Deficit Hyperactivity Disorder (ADHD), Oppositional Defiant Disorder (ODD), Phobias (Simple and Social), Obsessive Compulsive Disorder (OCD), Generalized Anxiety Disorder (GAD), and Mood disorders were present in both ASP and HFA.  Chi-square analyses revealed no significant between-group (HFA vs. ASP) differences in the rate of comorbidity for any of these diagnoses:  Criteria for ADHD were met in 20% of those with ASP and 13% of those with HFA. Criteria for ODD were met in 20% of subjects with ASP and 10% in those with HFA.  Criteria for Simple or Social Phobias were met in 28% of those with ASP and 23% of those with HFA. Criteria for OCD were met in 6% of those with ASP and 11% of those with HFA.  Criteria for a past diagnosis of Major Depressive Disorder (MDD) was met in 8% of ASP and 3% of HFA had and one subject with HFA met criteria for a Dysthymic Disorder. None of the subjects in either group met criteria for Bipolar Disorder, Separation Anxiety Disorder, Panic Disorder, Somatization Disorder, or for a current diagnosis of MDD.

Conclusions:

Children on the autism spectrum, whether HFA or ASP, experience significant comorbid psychopathology.  These findings highlight the importance of carefully examining these disorders, as they are potential targets for effective treatment.