Exploratory Profile of High Functioning Adolescents and Adults with Autism Spectrum Disorders Experiencing Subthreshold Psychotic Symptoms

Background: In the general population, subthreshold psychotic symptoms are associated with impaired functioning, and increased rates of ADHD, depression, and anxiety. Less is known regarding these relationships within the context of autism spectrum disorders (ASD).

Objectives: The purpose of the current study is to assess the relative impact of caregiver-observed psychotic symptoms for adolescents and adults with ASD. We hypothesized that elevated subthreshold psychotic symptoms would be associated with greater difficulties in executive, adaptive, and social functioning. Subthreshold psychotic symptoms were also predicted to increase psychiatric complexity, as documented by elevated associations with other psychiatric diagnoses, such as ADHD, mood, and anxiety disorders.   

Methods: Sixty-one adolescents and young adults (12-25 years) with high functioning ASD (Mean IQ=109.62; SD=15.35) participated in the study. Behavioral symptoms were assessed via caregiver report using the Adolescent Symptom Inventory-4 (ASI) or the Adult Inventory-4 (AI), which tap behavioral symptoms aligning with DSM-IV criteria for psychiatric disorders. The ASI/AI includes items assessing positive, negative, and disorganized schizophrenia symptoms. Pearson correlations were used to assess the strength of association between schizophrenia symptom severity and caregiver-reported executive function (BRIEF), adaptive functioning (ABAS-II), and social impairments (SRS). Linear regression was utilized to examine how schizophrenia symptom severity predicted severity of symptoms found in other DSM-IV disorders (i.e., ADHD combined, generalized anxiety disorder, major depressive disorder) based on the ASI/ASI severity scores.

Results: More than half of the sample (59.0%) endorsed at least one subthreshold psychotic symptom (Mean = 2.15; SD = 2.34). Schizophrenia severity scores were significantly correlated with age (r = .40, p = .001), overall executive function difficulties (r = .33, p = .01), greater social difficulties (r = .38, p = .002), and overall adaptive functioning (r = -.39, p = .003). IQ, race, and gender were not significantly associated with symptoms of psychosis. After adjusting for effects of age, schizophrenia symptom severity was associated with greater symptom severity associated with ADHD (Standardized Beta = 0.25; t = 2.00, p = .05) and generalized anxiety (Standardized Beta = 0.23; t = 2.48, p = .02), but not depression.

Conclusions: Adolescents/young adults with ASD experiencing subthreshold psychotic symptoms exhibit greater functional deficits including adaptive, executive, social, as well as more severe anxiety and attention problems than individuals with ASD alone. These behavioral difficulties indicate a potential point for early identification and possible intervention to ameliorate distress and dysfunction associated with subthreshold psychotic symptoms. Further research exploring the nature and validity of these subthreshold psychotic symptoms in the context of ASD is warranted.