Striatal size and relative glucose metabolic rate in schizotypal personality disorder and schizophrenia

Background: Schizotypal personality disorder (SPD) shares social deficits a nd cognitive impairment with schizophrenia, but is not typically characteri zed by frank psychosis. Because striatal size and functional activity have both been shown to be associated with psychotic symptoms, we carried out th e first study of SPD to assess the caudate and putamen for comparison with findings in schizophrenia. Methods: Patients with SPD (n=16), schizophrenic patients (n=42), and age- and sex-matched normal control subjects (n=47) were assessed with magnetic resonance imaging. All of the patients with SPD and subsamples of the schiz ophrenic patients (n=27) and control subjects (n=32) were also assessed wit h positron emission tomography using fluorodeoxyglucose F-18. Results: The relative size of the putamen in controls was significantly lar ger than in patients with SPD and significantly smaller than in schizophren ic patients, while the relative size of the caudate was similar in all 3 gr oups. Compared with control values, relative glucose metabolic rate in the ventral putamen was significantly elevated, in patients with SPD and reduce d in schizophrenic patients. When subsamples of schizophrenic patients (n=1 0) and patients with SPD (n=10) both of whom never received medication were compared, this pattern was more marked, with the highest value for the put amen being found in patients with SPD for the ventral slice and the lowest value for the right dorsal putamen. Conclusions: Patients with SPD showed reduced volume and elevated relative glucose metabolic rate of the putamen compared,,vith both schizophrenic pat ients and controls. These alterations in volume and activity may be related to the sparing of patients with SPD from frank psychosis.