Autistic traits distribution in different psychiatric conditions: A cluster analysis on the basis of the Adult Autism Subthreshold Spectrum (AdAS Spectrum) questionnaire.

Increasing interest is being paid on full-threshold and sub-threshold autism spectrum conditions among adults. Sub-threshold autistic traits (AT) seem to be distributed in a continuum from the clinical to the general population, being particularly higher among subjects with other psychiatric disorders. The aim of the present study was to evaluate the distribution of AT in a sample of subjects with different psychiatric conditions by means of a cluster analysis on the basis of the score reported to the AdAS Spectrum instrument. A total of 738 subjects recruited by seven Italian Universities were divided in 5 groups depending on the clinical diagnosis: Autism spectrum disorder (ASD), subthreshold ASD symptoms (partial ASD), Bipolar disorder (BD), Feeding and eating disorders (FED), and controls (CTLs). All subjects were assessed with the AdAS Spectrum. The cluster analysis identified 3 clusters: the high, medium and low autism clusters. The Restricted interests and rumination domain reported the highest influence in forming the clusters. The high, medium and low autism clusters were respectively more represented in the ASD, partial ASD and CTL groups. The clusters were represented intermediately in the FED and BD groups, confirming the presence of intermediate levels of AT in these clinical populations.