Psychopathology and Adaptive Functioning in Individuals with Autism Spectrum Disorders, First Episode Schizophrenia, and Clinical-High-Risk for Psychosis

Background:

Individuals with autism and schizophrenia share many common symptoms. However, few studies have systematically investigated similarities and differences in the behavioral phenotypes of adolescents with autism spectrum disorders (ASDs), first-episode schizophrenia (FEP), and clinical-high-risk for conversion to a psychotic disorder (CHR).

Objectives:

The goal of this study was to compare ASD, FEP, and CHR on measures of co-morbid psychopathology and adaptive functioning. This program of research can provide a means to improve "deep phenotyping" of autism and schizophrenia, assist in differential diagnosis, provide insights for psychosis risk prevention, and reveal differences in the neural mechanisms involved in symptom development and to enhance treatment matching.

Methods:

Four groups of age and IQ-matched ASD (n=19), CHR (n=12), and FEP (n=14) and typically developing (n=15) adolescents aged 12-20 were recruited from the MIND Institute, and the Imaging Research Center at UC Davis Medical Center. They were assessed using gold standard diagnostic measures for each disorder. Parents completed the Behavior Assessment System for Children 2 (BASC-2; Reynolds, 2004), which assesses current functioning.  The BASC-2 consists of both clinical (hyperactivity, aggression, conduct problems, anxiety, depression, atypicality, withdrawal and attention problems.) and adaptive behavior scales (adaptability, social skills, leadership, activities in daily life and functional communication). Means from normed scores were compared using appropriate parametric and non-parametric univariate tests with correction for multiple comparisons.

Results:

All clinical groups evidenced significant levels of psychopathology relative to TYP. CHR demonstrated the highest overall level of psychopathology, driven by elevations on the depression, aggression, and conduct sub-scales. CHR resembled ASD in hyperactivity. The ASD group was distinguished by their high scores on the atypicality and withdrawal sub-scales. All clinical groups showed comparable levels of anxiety, and attention problems. The clinical groups exhibited similar deficits relative to typically developing adolescents across the adaptive functioning sub-scales, although the ASD and CHR groups tended to be the most impaired.

Conclusions:

These preliminary results suggest that the clinical groups showed relatively discrete patterns of current co-morbid psychopathology. Individuals with CHR, and to a lesser extent FEP, were most likely to display current aggression and conduct problems, suggesting that this form of externalizing behavior may be more characteristic of individuals on the schizophrenia spectrum and a risk marker for the development of psychotic disorders. Adolescents with ASDs were unique in their atypicality and social withdrawal, suggesting that these symptoms are more characteristic of ASD. Despite these patterns, the groups also exhibited considerable similarities. The ASD and CHR groups displayed comparable and elevated hyperactivity. All three clinical groups evidenced similar anxiety and attention problems suggesting that schizophrenia and autism may share common endophenotypes. All groups displayed significant deficits in adaptive functioning relative to TYP.