Temporal lobe volume determined by magnetic resonance imaging in schizotypal personality disorder and schizophrenia.

The volumes of the whole temporal lobe, the superior temporal gyrus and the corpus callosum were measured on magnetic resonance images from 13 patients with schizotypal personality disorder (SPD), 27 patients with schizophrenia, and 31 age- and sex-matched controls. Temporal lobe structures were traced on consecutive 1.2mm thick SPGR images. Both patient groups had smaller temporal lobes than normal volunteers, a difference that was more marked for the area outside the superior temporal gyrus than for the STG. Correcting for brain volume diminished differences between normal subjects and schizophrenia patients, but the differences between normal subjects and SPD patients remained. Normal volunteers and SPD patients showed significant correlations between the sagittal section area of the posterior portion of the corpus callosum, which carries temporal interhemispheric connections, and the white matter volume of the temporal lobe. While the sample size is modest, taken together, these results suggest that the psychopathological symptoms of SPD may be related to temporal gray matter loss with relatively intact white matter connectivity, while the cognitive and psychotic symptoms of schizophrenia may be related to temporal gray loss combined with disruption of normal patterns of white matter development.

Performance of patients with schizophrenia on a pen and paper visuospatial working memory task with short delay.

Human and nonhuman primate data suggest that visuospatial working memory is mediated by a neural network that includes the prefrontal cortex. Simple working memory tasks are less complex than standard neuropsychological tests of frontal dysfunction. As such, they are less vulnerable to general performance factors such as amotivation and uncooperativeness in schizophrenic patients. These tasks thus hold promise as potential measures of frontal dysfunction in schizophrenia. However, the specific parameters of visuospatial working memory deficit in schizophrenia have not been established. This study assessed working memory functions in 18 schizophrenic patients and 28 controls using a pen-and-paper analogue of a monkey prefrontal cortex activation task. Schizophrenic patients and controls performed similarly on a sensory-guided task that did not require working memory functions, yet schizophrenic patients performed significantly worse than controls on tasks that required subjects to retain visuospatial information for delay periods of 10 and 20 s. These data suggest that the working memory deficits in patients with schizophrenia begin to appear less than 10 s following encoding of visuospatial information and that these working memory deficits can be assessed with easily administered pen-and-paper tasks.

Cognitive function and biological correlates of cognitive performance in schizotypal personality disorder.

There is evidence that some schizophrenic patients have deficits on tests of cognitive function, particularly tests of executive function, including the Wisconsin Card Sorting Test (WCST) and the Trail-making Test, Part B. This study was conducted to determine the generalizability of these findings across the schizophrenia spectrum to schizotypal personality disorder (SPD). Forty DSM-III SPD patients, 56 nonschizophrenia-related other personality disorder (OPD) patients, and 32 normal volunteers from two medical centers performed tests of executive function such as the WCST, Trail-making Part B, Stroop Word-Color Test, and Verbal Fluency, as well as tests of more general intellectual functioning such as the Wechsler Intelligence Scale-Revised Vocabulary and Block Design subtests, and Trail-making Part A. SPD patients performed more poorly on the WCST and on Trail-making Part B than did OPD patients or normal subjects; the groups did not differ on tests of general intellectual functioning. SPD patients may share some of the cognitive deficits observed in schizophrenia.