Objective: Schizophrenia spectrum subjects have cognitive deficits in a variety of domains. Schizotypal personality disordered (SPD) subjects do not have many of the confounds seen in schizophrenic patients, but may have the same pattern of cognitive deficits in attention and executive functioning.
Hypothesis: We hypothesized that SPD subjects would have impairments on measures of attention, abstract reasoning, cognitive inhibition, working memory and verbal recognition memory when compared to normal subjects, and that these deficits would be intermediate to those observed in schizophrenic patients.
Method: SPD subjects (N=20) were compared to age-, gender- and education-matched schizophrenic patients (N=20) and normal comparison subjects (N=20) on a battery of cognitive measures.
Results: The data were analyzed using standard statistical methods, including effect sizes. Using a conservative alpha level of 0.01, schizophrenic patients had deficits on many of these measures compared to normal subjects. Although the SPD subjects did not significantly differ from normal comparison subjects at the p < 0.01 level, there were trends (p < 0.019-0.028) toward impairment on measures of working memory and general intellectual functioning. On further effect size analyses, SPD subjects performed intermediate to normals and schizophrenic patients on measures of attention, abstract reasoning, cognitive inhibition, verbal working memory, recognition memory, and general intellectual functioning, with moderate to large effect sizes separating groups.
Conclusions: These results suggest that SPD subjects have possible widespread cognitive deficits that are of lesser magnitude than those observed in schizophrenic patients.