Advancing understanding of the classification of broad autism phenotype and attention-deficit/hyperactivity disorder symptom dimensions within the Hierarchical Taxonomy of Psychopathology.

Research on personality and psychopathology associations has informed the classification of many symptom dimensions within the Hierarchical Taxonomy of Psychopathology (HiTOP). However, classification of symptom dimensions defining autism and attention-deficit/hyperactivity disorder (ADHD) within the HiTOP framework remains unclear in many ways. To address this issue, we examined the joint factor structure of (a) measures assessing characteristics relevant to ADHD and autism and (b) normal range personality traits in a sample of 547 adults recruited from Amazon Mechanical Turk, many of whom reported elevated autism-relevant and ADHD-relevant characteristics. We also examined how factors identified in these analyses correlated with measures of internalizing symptoms and select externalizing traits. Our results indicated that some measures assessing autism-relevant and ADHD-relevant characteristics (e.g. communication issues, hyperactivity/impulsivity) defined a distinct Attention and Communication Difficulties factor, with scores on this factor correlating strongly with internalizing symptom ratings. However, other relevant characteristics such as aloofness may be indicators of existing HiTOP spectra such as detachment. We discuss how these findings inform classification of autism-relevant and ADHD-relevant characteristics within the HiTOP, as well as key future directions for extending the limited research in this area.