Schizotypal personality disorder (SPD) shares social deficits and cognitive impairment with schizophrenia, but is not typically characterized by frank psychosis. Because striatal size and functional activity have both been shown to be associated with psychotic symptoms, we carried out the first study of SPD to assess the caudate and putamen for comparison with findings in schizophrenia.
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 schizophrenic patients (n = 27) and control subjects (n = 32) were also assessed with positron emission tomography using fluorodeoxyglucose F-18.
The relative size of the putamen in controls was significantly larger than in patients with SPD and significantly smaller than in schizophrenic patients, while the relative size of the caudate was similar in all 3 groups. Compared with control values, relative glucose metabolic rate in the ventral putamen was significantly elevated in patients with SPD and reduced in schizophrenic patients. When subsamples of schizophrenic patients (n = 10) 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 putamen being found in patients with SPD for the ventral slice and the lowest value for the right dorsal putamen.
Patients with SPD showed reduced volume and elevated relative glucose metabolic rate of the putamen compared with both schizophrenic patients and controls. These alterations in volume and activity may be related to the sparing of patients with SPD from frank psychosis.
"However, relative to schizophrenia, the number of MRI volumetric studies of SPD is smaller. Moreover , many of the studies looked at small regions of interest (ROIs), had findings that were sometimes inconsistent, and generally had a small number of participants, with UM or NN ROI STG↓, temporal structures without STG↓ Shihabuddin et al, 18 2001 SPD: 15/ "
[Show abstract][Hide abstract] ABSTRACT: IMPORTANCE Some, but not all, previous magnetic resonance imaging studies have indicated smaller cortical and local gray matter volumes (GMVs) in men with schizotypal personality disorder (SPD) compared with healthy control (HC) subjects. Thus, there is need for a whole-brain comparison to resolve inconsistencies and provide hitherto generally absent data on the association between GMV and symptoms. OBJECTIVE To use voxel-based morphometry to evaluate a large sample of neuroleptic-naive men with SPD compared with group-matched HC subjects on local and global GMV and to identify associations with symptoms, especially negative symptoms. Also, to determine whether age-related GMV reductions are greater in men with SPD than HC subjects, providing presumptive evidence on possible progression. DESIGN, SETTING, AND PARTICIPANTS This naturalistic study involved 54 neuroleptic-naive men with SPD and 54 male HC subjects aged 18 to 55 years recruited from the community and scanned on the same 1.5-T GE magnetic resonance imaging scanner. Participants were group matched on age, socioeconomic status, handedness, and IQ. MAIN OUTCOME MEASURES Cross-sectional voxel-based morphometry, GMV in subjects with SPD and HC participants, and the relationship to clinical symptoms. RESULTS A voxelwise analysis showed participants with SPD had significantly smaller GMV in the left superior temporal gyrus and widespread frontal, frontolimbic, and parietal regions compared with HC subjects. Most of these regional volumes were strikingly and significantly correlated with negative symptoms: the more the volume reduction, the more negative symptoms. Global cortical GMV and most regional GMV showed significant negative relationships with age in both those with SPD and HC subjects, without any group by age interactions. CONCLUSIONS AND RELEVANCE Men with SPD showed global and widespread smaller regional GMV. The regional structural abnormalities were correlated with the severity of a participant's negative symptoms. While the pattern of GMV loss is similar to that in schizophrenia, the similar patterns of HC-SPD age-related GMV reduction suggest that SPD showed no progressive GMV loss, pointing to an important difference in the biological mechanisms of SPD and schizophrenia.
"Previously, the effects of aging (Gunning-Dixon et al., 1998; Xu et al., 2000; Gunduz et al., 2002; Gur et al., 2002; Brabec et al., 2003) and disease (Shihabuddin et al., 2001; Strakowski et al., 2002; Gunduz et al., 2002; Levitt et al., 2002; Lacerda et al., 2003; Buchsbaum et al., 2003; Aylward et al., 2004; Deshmukh et al., 2005; Hollander et al., 2005) in the volume of the striatum have been studied. However, shape could provide additional and complimentary information about local structural alterations meaningful in the context of functional neuroanatomy. "
[Show abstract][Hide abstract] ABSTRACT: Human striatum is involved in the regulation of movement, reinforcement, learning, reward, cognitive functioning, and addiction. Previous classical volumetric MRI studies have implicated age-, disease- and medication-related changes in striatal structures. Yet, no studies to date have addressed the effects of these factors on the shape variability and local structural alterations in the striatum. The local alterations may provide meaningful additional information in the context of functional neuroanatomy and brain connectivity. We developed image analysis methodology for the measurement of the volume and local shape variability of the human striatum. The method was applied in a group of 43 healthy controls to study the effects of age and gender on striatal shape variability. In the volume analysis, the volume of the striatum was normalized using the volume of the whole brain. In the local shape analysis, the deviations from a mean surface were studied for each surface point using high-dimensional mapping. Also, discriminant functions were constructed from a statistical shape model. The accuracy and reproducibility of the methods used were evaluated. The results confirmed that the volume of the striatum decreases as a function of age. However, the volume decrease was not uniform and age-related shape differences were observed in several subregions of the human striatum whereas no local gender differences were seen. Examination of the variability of striatal shape in the healthy population will pave the way for applying this method in clinical settings. This method will be particularly useful for investigating neuropsychiatric disorders that are associated with subtle morphological alterations of the brain, such as schizophrenia.
"Subjects diagnosed with SPD also share a number of psychophysiological abnormalities observed in schizophrenia, including deficits in prepulse inhibition (Cadenhead et al 2000) and numerous cognitive deficits (Niznikiewicz et al 1999). Additionally structural and functional studies have suggested that temporal lobe (Dickey et al 2002, 2003), striatum and thalamus (Byne et al 2001; Shihabuddin et al 2001), and ventricle volume (Buchsbaum et al 1997) are abnormal in SPD, as well as in schizophrenia. Taken together, the genetic, cognitive, and brain morphological similarities reported between schizophrenia and SPD (Dickey et al 2002; Siever and Davis 2004) suggest that the pathology found in SPD has implications for understanding pathology in schizophrenia. "
[Show abstract][Hide abstract] ABSTRACT: The caudate nucleus might contribute to the psychopathological and cognitive deficits observed in schizotypal personality disorder (SPD), a schizophrenia spectrum disorder. Here we focused on female patients, because this group is underrepresented in studies of SPD and schizophrenia, and we might learn more about the caudate and clinical and cognitive impairments that are unique to female patients diagnosed with SPD.
Magnetic resonance imaging scans, obtained on a 1.5-T magnet with 1.5-mm contiguous slices, were used to measure the caudate in 32 neuroleptic-naïve women with SPD and in 29 female normal comparison subjects. Subjects were group-matched for age, parental socioeconomic status, and intelligence quotient.
We found significantly reduced left and right caudate relative volume (8.3%, 7.7%) in female SPD subjects compared with normal comparison subjects. In female SPD subjects, we found significant correlations between smaller total caudate relative volume and worse performance on the Wisconsin Card Sorting test (nonperseverative errors) and on the California Verbal Learning Test (verbal memory and learning), and significant correlations between smaller total caudate relative volume and both positive and negative symptoms on the Structured Interview for Schizotypy.
These findings demonstrate that, for female SPD subjects, smaller caudate volume is associated with poorer cognitive performance and more schizotypal symptomatology.
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