Bernard Crespi

Simon Fraser University
 

Complex human social cognition has evolved in concert with risks for psychiatric disorders of social cognition. We have developed the theory that autism and psychotic-affective conditions represent opposite disorders with regard to their risk factors and core phenotypes, with autism involving underdeveloped sociality, and psychotic-affective conditions involving dysfunctionally hyper-developed social cognition. We have now tested this theory by genotyping a large nonclinical Caucasian population for a set of well-characterized schizophrenia risk SNPs, under the prediction that higher levels of autism spectrum psychological traits should be found among individuals with fewer schizophrenia risk alleles. This prediction was supported for males, under one genetic model of risk.  Most of this effect, however, was attributable to the autism-spectrum trait ‘social imagination’, such that genetic risk of schizophrenia was positively associated with higher imagination. Taken together, our findings suggest that imagination represents a core diametric phenotype of both sets of conditions, being lower in autism and higher in psychotic-affective conditions.  We describe how increased imagination may have centrally characterized the evolution of human social cognition, how alterations to imagination can explain most of the central symptoms of these psychiatric conditions, and how imagination can serve as a nexus for psychological treatments.