Schizotypal personality disorder and MRI abnormalities of temporal lobe gray matter.
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BACKGROUND: Structural MRI data indicate schizophrenics have reduced left-sided temporal lobe gray matter volumes, especially in the superior temporal gyrus (STG) and medial temporal lobe. Our data further suggest a specificity to schizophrenia spectrum disorders of STG volume reduction. Interpretation of research studies involving schizophrenics may be complicated by the effects of exposure to neuroleptics and chronic illness. Sharing the same genetic diathesis of schizophrenics, subjects with schizotypal personality disorder (SPD) offer a unique opportunity to evaluate commonalities between schizophrenia and SPD, particularly as SPD subjects are characterized by cognitive and perceptual distortions, an inability to tolerate close friendships, and odd behavior, but they are not psychotic and so have generally not been prescribed neuroleptics nor hospitalized. Evaluation of brain structure in SPD may thus offer insight into the "endophenotype" common to both disorders. In addition, differences between groups may suggest which are the brain structures of schizophrenics that contribute to the development of psychosis. METHODS: To test the hypothesis of whether SPD subjects might show similar STG abnormalities, STG and medial temporal lobe regions of interest (ROI) were manually drawn on high resolution coronal MRI 1.5 mm thick slices. Images were derived from 16 right-handed male SPD subjects, without regard to family history, and 14 healthy, right-handed, comparison males who did not differ from the SPD group on parental socio-economic status, age, or verbal IQ. RESULTS: As predicted, SPD subjects showed a reduction in left STG gray matter volume compared with age and gender matched comparison subjects. SPD subjects also showed reduced parahippocampal left/right asymmetry and a high degree of disordered thinking. Comparisons with chronic schizophrenics previously studied by us showed the SPD group had a similarity of left STG gray matter volume reduction, but fewer medial temporal lobe abnormalities. CONCLUSIONS: These abnormalities strengthen the hypothesis of a temporal lobe abnormality in SPD, and the similarity of STG findings in schizophrenia and SPD suggest that STG abnormalities may be part of the spectrum "endophenotype." It is also possible that presence of medial temporal lobe abnormalities may help to differentiate who will develop schizophrenia and who will develop the less severe schizophrenia spectrum disorder, SPD. (+info)
Electrophysiological correlates of language processing in schizotypal personality disorder.
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OBJECTIVE: This study examined whether the electrophysiological correlates of language processing found previously to be abnormal in schizophrenia are also abnormal in schizotypal individuals. The authors used the N400 component to evaluate language dysfunction in schizotypal individuals. METHOD: Event-related potentials were recorded in 16 comparison subjects and 17 schizotypal individuals (who met full DSM-III-R criteria) to sentences presented both visually and aurally; half of the sentences ended with an expected word completion (congruent condition), and the other half ended with an unexpected word completion (incongruent condition). RESULTS: In the congruent condition, the N400 amplitude was more negative in individuals with schizotypal personality disorder than in comparison subjects in both the visual and auditory modalities. In addition, in the visual modality, the N400 latency was prolonged in the individuals with schizotypal personality disorder. CONCLUSIONS: The N400 was found to be abnormal in the individuals with schizotypal personality disorder relative to comparison subjects. The abnormality was similar to the abnormality the authors' laboratory reported earlier in schizophrenic subjects, in which the N400 amplitude was found to be more negative in both congruent and incongruent sentence completions. The N400 abnormality is consistent with the inefficient use of context. (+info)
Validity and usefulness of the Wisconsin Manual for Assessing Psychotic-like Experiences.
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The Wisconsin Manual for Assessing Psychotic-like Experiences is an interview-based assessment system for rating psychotic and psychotic-like symptoms on a continuum of deviancy from normal to grossly psychotic. The original manual contained six scales, assessing thought transmission, passivity experiences, thought withdrawal, auditory experiences, personally relevant aberrant beliefs, and visual experiences. A seventh scale assessing deviant olfactory experiences was subsequently added. The rating scales have good interrater reliability when used by trained raters. Cross-sectional studies indicated that the frequency and deviancy of psychotic-like experiences are elevated among college students who were identified, hypothetically, as psychosis prone by other criteria. Psychotic-like experiences of moderate deviancy in college students successfully predicted the development of psychotic illness and poorer overall adjustment 10 years later. The manual is useful for identifying psychosis-prone individuals and is recommended for use in linkage and treatment outcome studies. The present article provides an interview schedule for collecting information required for rating psychotic-like experiences. (+info)
Measurement of delusional ideation in the normal population: introducing the PDI (Peters et al. Delusions Inventory).
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The Peters et al. Delusions Inventory (PDI) was designed to measure delusional ideation in the normal population, using the Present State Examination as a template. The multidimensionality of delusions was incorporated by assessing measures of distress, preoccupation, and conviction. Individual items were endorsed by one in four adults on average. No sex differences were found, and an inverse relationship with age was obtained. Good internal consistency was found, and its concurrent validity was confirmed by the percentages of common variance with three scales measuring schizotypy, magical ideation, and delusions. PDI scores up to 1 year later remained consistent, establishing its test-retest reliability. Psychotic inpatients had significantly higher scores, establishing its criterion validity. The ranges of scores between the normal and deluded groups overlapped considerably, consistent with the continuity view of psychosis. The two samples were differentiated by their ratings on the distress, preoccupation, and conviction scales, confirming the necessity for a multidimensional analysis of delusional thinking. Possible avenues of research using this scale and its clinical utility are highlighted. (+info)
Large CSF volume not attributable to ventricular volume in schizotypal personality disorder.
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OBJECTIVE: The purpose of this study was to determine whether schizotypal personality disorder, which has the same genetic diathesis as schizophrenia, manifests abnormalities in whole-brain and CSF volumes. METHOD: Sixteen right-handed and neuroleptic-naive men with schizotypal personality disorder were recruited from the community and were age-matched to 14 healthy comparison subjects. Magnetic resonance images were obtained from the subjects and automatically parcellated into CSF, gray matter, and white matter. Subsequent manual editing separated cortical from noncortical gray matter. Lateral ventricles and temporal horns were also delineated. RESULTS: The men with schizotypal personality disorder had larger CSF volumes than the comparison subjects; the difference was not attributable to larger lateral ventricles. The cortical gray matter was somewhat smaller in the men with schizotypal personality disorder, but the difference was not statistically significant. CONCLUSIONS: Consistent with many studies of schizophrenia, this examination of schizotypal personality disorder indicated abnormalities in brain CSF volumes. (+info)
Visual perception and working memory in schizotypal personality disorder.
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OBJECTIVE: Patients affected by schizophrenia show deficits in both visual perception and working memory. The authors tested early-stage vision and working memory in subjects with schizotypal personality disorder, which has been biologically associated with schizophrenia. METHOD: Eleven subjects who met DSM-III-R criteria for schizotypal personality disorder and 12 normal comparison subjects were evaluated. Performance thresholds were obtained for tests of visual discrimination and working memory. Both form and trajectory processing were evaluated for each task. RESULTS: Subjects with schizotypal personality disorder showed intact discrimination of form and trajectory but were impaired on working memory tasks. CONCLUSIONS: These data suggest that subjects with schizotypal personality disorder, unlike patients affected by schizophrenia, have relatively intact visual perception. Subjects with schizotypal personality disorder do show specific deficits on tasks of comparable difficulty when working memory demands are imposed. Schizotypal personality disorder may be associated with a more specific visual processing deficit than schizophrenia, possibly reflecting disruption of frontal lobe systems subserving visual working memory operations. (+info)
Verbal and nonverbal neuropsychological test performance in subjects with schizotypal personality disorder.
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OBJECTIVE: The authors contrasted verbal and nonverbal measures of attention and memory in patients with DSM-IV-defined schizotypal personality disorder in order to expand on their previous findings of verbal learning deficits in these patients and to understand better the neuropsychological profile of schizotypal personality disorder. METHOD: Cognitive test performance was examined in 16 right-handed men who met diagnostic criteria for schizotypal personality disorder and 16 matched male comparison subjects. Neuropsychological measures included verbal and nonverbal tests of persistence, supraspan learning, and short- and long-term memory retention. Neuropsychological profiles were constructed by standardizing test scores based on the means and standard deviations of the comparison subject group. RESULTS: Subjects with schizotypal personality disorder showed a mild to moderate general reduction in performance on all measures. Verbal measures of persistence, short-term retention, and learning were more severely impaired than their nonverbal analogs. Performance on measures of memory retention was independent of modality. CONCLUSIONS: The results are consistent with previous reports that have suggested a mild, general decrement in cognitive performance and proportionately greater involvement of the left hemisphere in patients with schizotypal personality disorder. The findings provide further support for a specific deficit in the early processing stages of verbal learning. (+info)
The multidimensionality of self-report schizotypy in a psychiatric population: an analysis using multidimensional Rasch models.
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There is increasing empirical evidence from factor analytical studies that schizotypy is composed of three dimensions. All studies into the multidimensionality of schizotypy used common factor analysis of scales, either exploratory or confirmatory. We argue that for research into the multidimensionality of schizotypy with dichotomous item responses on questionnaires (as with the Schizotypal Personality Questionnaire [SPQ], Raine 1991) much can be learned using generalized multidimensional Rasch models (GMRMs). GMRMs require a priori postulated models of schizotypy, which can be tested in confirmatory analyses. We hypothesized four competing models of schizotypy, based on the literature and clinical impressions-two two-dimensional models and two three-dimensional models. We also hypothesized that items differ in the degree they are indicative of a particular dimension of schizotypy. The sample was 418 psychiatric inpatients and outpatients, with moderate levels of psychopathology, who filled in the SPQ. Both three-dimensional models yielded a much better fit to the data than both two-dimensional models. Our revised three-dimensional model, a revision of that by Raine et al. (1994) and Gruzelier (1996), yielded the best fit. It consisted of positive schizotypy, disorganization, and negative schizotypy. The results strongly suggest that schizotypy, as measured with the SPQ, is a three-dimensional construct. (+info)