Response inhibition in autistic children predicts positive psychotic symptoms in young adulthood: Results from an 8-year follow-up study

Attenuated positive symptoms are common in autism and currently constitute the most well-validated vulnerability marker for psychosis. Early deviations in executive functioning and social cognition are believed to contribute to the onset of these symptoms. Therefore, it is important to evaluate their long-term predictive value for psychosis risk, particularly within the autism population, where these cognitive faculties are often diminished. This study aimed to compare psychotic symptoms in youth diagnosed with an autism spectrum condition (ASC) to a normative dataset (N=5546), and to determine their long-term stability over an 8-year period. In addition, it was tested whether cognitive markers assessed in childhood could predict positive symptoms in young adulthood. Follow-up data was available for 30 ASC individuals (Mage=20.1, 83.3% male). Cognitive assessments at baseline and psychotic symptom questionnaires at baseline and 8-year follow-up were analyzed. Results showed significant and moderate evidence for fewer positive symptoms in young adults with ASC compared to the normative sample. Positive and negative symptoms did not differ significantly over time and displayed weak correlations between both assessments, while disorganized symptoms showed a modest decrease and a significant correlation. Finally, response inhibition accuracy was a significant cognitive predictor of positive symptoms at follow-up. Contrary to expectations, our results suggest that self-reported psychotic symptoms are not elevated in young adults with ASC. These symptoms remain relatively stable from childhood to young adulthood, although individual differences in symptom change are substantial. Response inhibition may represent an early cognitive vulnerability marker for developing positive symptoms in young adulthood.