Evidence from structural and diffusion tensor imaging for frontotemporal deficits in psychometric schizotypy

Previous studies of nonclinical samples exhibiting schizotypal traits have provided support for the existence of a continuous distribution of psychotic symptoms in the general population. Few studies, however, have examined the neural correlates of psychometric schizotypy using structural and diffusion tensor imaging (DTI).

Healthy volunteers between the ages of 18 and 68 were recruited from the community and assessed using the Schizotypal Personality Questionnaire and received structural and DTI exams. Participants with high (N = 67) and low (N = 71) psychometric schizotypy were compared on gray and white matter volume, and cortical thickness in frontal and temporal lobe regions and on fractional anisotropy (FA) within 5 association tracts traversing the frontal and temporal lobes.

Higher levels of schizotypy were associated with lower overall volumes of gray matter in both the frontal and temporal lobes and lower gray matter thickness in the temporal lobe. Regionally specific effects were evident in both white matter and gray matter volume of the rostral middle frontal cortex and gray matter volume in the pars orbitalis. Moreover, relative to individuals who scored low, those who scored high in schizotypy had lower FA in the inferior fronto-occipital fasciculus as well as greater asymmetry (right > left) in the uncinate fasciculus.

These findings are broadly consistent with recent data on the neurobiological correlates of psychometric schizotypy as well as findings in schizotypal personality disorder and schizophrenia and suggest that frontotemporal lobe dysfunction may represent a core component of the psychosis phenotype.