How Are Autism and Schizotypy Related? Evidence from a Non-Clinical Population

Abstract

Both autism spectrum conditions (ASCs) and schizophrenia spectrum conditions (SSCs) involve altered or impaired social and communicative functioning, but whether these shared features indicate overlapping or different etiological factors is unknown. We outline three hypotheses (overlapping, independent, and diametric) for the possible relationship between ASCs and SSCs, and compare their predictions for the expected relationships between autistic and schizotypal phenotypes using the Autism Spectrum Quotient and the Schizotypal Personality Questionnaire-Brief Revised from a large non-clinical sample of undergraduate students. Consistent with previous research, autistic features were positively associated with several schizotypal features, with the most overlap occurring between interpersonal schizotypy and autistic social and communication phenotypes. The first component of a principal components analysis (PCA) of subscale scores reflected these positive correlations, and suggested the presence of an axis (PC1) representing general social interest and aptitude. By contrast, the second principal component (PC2) exhibited a pattern of positive and negative loadings indicative of an axis from autism to positive schizotypy, such that positive schizotypal features loaded in the opposite direction to core autistic features. These overall PCA patterns were replicated in a second data set from a Japanese population. To evaluate the validity of our interpretation of the PCA results, we measured handedness and mental rotation ability, as these are established correlates of SSCs and ASCs, respectively. PC2 scores were significantly associated with hand preference, such that increasingly ‘schizotypal’ scores predicted reduced strength of handedness, which is consistent with previous research. PC1 scores were positively related to performance on the mental rotation task, suggesting trade-offs between social skills and visual-spatial ability. These results provide novel evidence for an autism-positive schizotypy axis, and highlight the importance of recognizing that psychological variation involving reduced social interest and functioning may have diverse causes.

Oxytocin, testosterone, and human social cognition

“…The roles of testosterone and oxytocin in other psychiatric disorders involving dysregulated social cognition, especially the major psychotic‐affective disorders schizophrenia, bipolar disorder, and depression that share symptoms and risk factors, have been less well investigated than for autism, both theoretically and empirically; indeed, conceptual, hypothetic‐deductive frameworks have yet to be developed in this context, despite the obvious importance of social hormones in human psychological phenotypes. A recently developed model for understanding the psychotic‐affective disorders, in comparison to autism, is that they involve forms of dysfunctional, ‘hyper‐developed’ social cognition, as demonstrated, for example, in such phenotypes as paranoia, other social delusions, auditory hallucination, megalomania, high levels of social emotion including guilt, shame, pride, or embarrassment, high empathic drive, and high social motivation as observed in mania (Crespi & Badcock, ; Backasch et al, ; Dinsdale & Crespi, ; Dinsdale et al, ; Sharp et al, ; Crespi & Leach, ). This model is based on the simple presumptions that evolution along the human lineage has predominantly involved increases in social cognition and emotionality (the well‐supported ‘social brain’ hypothesis) (Dunbar & Shultz, ), and that all biological phenotypes can be perturbed in two opposite directions, towards either lower or higher expression of some trait, pathway, or system, both of which cause performance deficits although by different means.…”

Autistic and schizotypal traits and global functioning in bipolar I disorder

“…*=p<0.05; **=p<.01. (Dinsdale, Hurd, Wakabayashi, Elliot, & Crespi, 2013). Here, the PCA was conducted with a varimax rotation to maximize orthogonality and Kaiser Normalization.…”

Schizotypal personality questionnaire – brief revised (updated): An update of norms, factor structure, and item content in a large non-clinical young adult sample

“…At clinical levels of extremity, schizotypal traits are recognized as schizotypal personality disorder. However, they are not exclusive to the schizophrenia spectrum (Dinsdale et al, 2013). At more moderate levels, schizotypy is a source of variance in personal and social functioning (e.g., Fonseca-Pedrero et al, 2010a), a vulnerability or prodromal factor for psychosis (e.g., Horan et al, 2008b), and a stable trait-like feature of schizophrenia (e.g., Lenzenweger, 2011).…”