Andrea R. Sherwood

Substance use disorders in schizophrenia: review, integration, and a proposed model.

Substance use disorders occur in approximately 40 to 50% of individuals with schizophrenia. Clinically, substance use disorders are associated with a variety of negative outcomes in schizophrenia, including incarceration, homelessness, violence, and suicide. An understanding of the reasons for such high rates of substance use disorders may yield insights into the treatment of this comorbidity in schizophrenia. This review summarizes methodological and conceptual issues concerning the study of substance use disorders in schizophrenia and provides a review of the prevalence of this co-occurrence. Prevailing theories regarding the co-occurrence of schizophrenia and substance use disorders are reviewed. Little empirical support is found for models suggesting that schizophrenic symptoms lead to substance use (self-medication), that substance use leads to schizophrenia, or that there is a genetic relationship between schizophrenia and substance use. An integrative affect-regulation model incorporating individual differences in traits and responses to stress is proposed for future study.

Psychological and Cognitive Effects of Long-Term Peyote Use Among Native Americans

BACKGROUND Hallucinogens are widely used, both by drug abusers and by peoples of traditional cultures who ingest these substances for religious or healing purposes. However, the long-term residual psychological and cognitive effects of hallucinogens remain poorly understood. METHODS We recruited three groups of Navajo Native Americans, age 18-45: 1) 61 Native American Church members who regularly ingested peyote, a hallucinogen-containing cactus; 2) 36 individuals with past alcohol dependence, but currently sober at least 2 months; and 3) 79 individuals reporting minimal use of peyote, alcohol, or other substances. We administered a screening interview, the Rand Mental Health Inventory (RMHI), and ten standard neuropsychological tests of memory and attentional/executive functions. RESULTS Compared to Navajos with minimal substance use, the peyote group showed no significant deficits on the RMHI or any neuropsychological measures, whereas the former alcoholic group showed significant deficits (p < .05) on every scale of the RMHI and on two neuropsychological measures. Within the peyote group, total lifetime peyote use was not significantly associated with neuropsychological performance. CONCLUSIONS We found no evidence of psychological or cognitive deficits among Native Americans using peyote regularly in a religious setting. It should be recognized, however, that these findings may not generalize to illicit hallucinogen users.

Differences in cerebellar blood volume in schizophrenia and bipolar disorder

Brain morphometry has been studied extensively in schizophrenic patients, and among the cortical differences identified two consistent findings are decreased cerebellar vermal volume and increased volume of the fourth ventricle; although contradictory findings are reported as well. Recent cognitive activation studies utilizing PET, SPECT and fMRI have identified both decreased and increased activation in the cerebellum of schizophrenic patients compared with healthy controls. This study used DSC fMRI to map cerebellar blood volume in patients with schizophrenia or bipolar disorder and healthy controls. For all cerebellar regions analyzed, schizophrenic patients had the highest cerebellar blood volume, while bipolars had the lowest blood volume. Morphometric measurements were completed and indicated that the ratio of vermis to whole CBL tissue volume was 24% less for the schizophrenic population than controls, whereas the subjects with bipolar disorder had a ratio that was non-significantly smaller than controls by 19%. Comparison of morphometric data with blood volume data did not reveal any statistically significant correlations among the study groups.

Cerebellar blood volume in bipolar patients correlates with medication

BACKGROUND Cerebellar abnormalities, including decreased tissue volume, have been implicated in the pathophysiology of bipolar disorder. Relatively little research has focused on blood flow in the cerebellum of patients with bipolar disorder. Furthermore, the significance of metabolic changes in the brains of psychiatric patients may be confounded by the effects of various pharmacotherapies. Having previously found differences in cerebellar blood volume in patients with bipolar disorder compared to healthy control subjects, this study examined whether some variability in the patient population may be an effect of medication. METHODS In this study, we have examined the association between medication status and cerebellar blood volume. Thirteen healthy comparison subjects and 21 bipolar patients underwent dynamic susceptibility contrast magnetic resonance imaging. Nine cerebellar regions were identified, and the absolute cerebellar blood volume data from each was compared to medication status measures. RESULTS Patients on conventional antipsychotics had the lowest mean absolute blood volume measures for all cerebellar regions, whereas those on atypical antipsychotics had the highest blood volume measures. Comparison subjects had cerebellar blood volume measures in the middle, with results closer to subjects in the atypical group. CONCLUSIONS This evidence suggests that antipsychotic treatment may influence cerebellar blood volume. This effect will be important in considering imaging studies on medicated patients with bipolar disorder and may suggest novel pathways by which these medications affect their changes.

Mesial temporal lobe Cho to Cr(PCr) ratio asymmetry in chronic schizophrenics.

Proton magnetic resonance spectra (MRS) were acquired from 1.5 x 1.5 x 1.5-cm voxels in the left and right mesial temporal lobes of 20 schizophrenic patients and 20 non-psychiatric comparison subjects. Choline (Cho) to creatine (and phosphocreatine) (Cr(PCr)) ratios were estimated as were the percent gray matter, white matter and CSF contributing to the voxel. The Cho/Cr(PCr) metabolite ratio was significantly lower in the left temporal lobe than in the right temporal lobe for both the schizophrenia subjects and control group. This difference was greater in the schizophrenia subjects. Left temporal lobe gray matter voxel content was significantly higher and white matter content was significantly lower than in the right temporal lobe for both the schizophrenia subjects and control group. This difference was the same for the schizophrenia subjects and control group. Left voxel gray matter and white matter content correlated with Cho/Cr(PCr) metabolite ratios for the schizophrenic subjects but not for the control subjects. No such correlations were noted on the right side. No significant difference was found between Cho/Cr(PCr) in the left temporal lobe or in the right temporal lobe of the schizophrenia subjects vs. the control group.

Two Case Reports of Neuropsychological Outcomes following Pediatric anti-N-methyl D-aspartate Receptor Autoimmune Encephalitis

ABSTRACT Anti-NMDAR autoimmune encephalitis is a rare neurological condition. Limited existing pediatric case studies have shown mild, but persisting, neuropsychological impairments. This report described neuropsychological functioning in two patients treated for anti-NMDAR autoimmune encephalitis. Patient A is a 16-year-old male (10 months after symptom onset) and Patient B is a 5-year-old female (45 months after symptom onset). Contrary to expectations, their cognitive profiles were largely intact, raising the possibility of minimal cognitive implications for some pediatric patients with this condition. Additional research is needed to identify factors that contribute to better cognitive outcomes in children with anti-NMDAR autoimmune encephalitis.

675 - Temporal P300 asymmetry in first episode schizophrenia

event-related brain potentials (ERPs) are examined to uncover electrocortical correlates of cognitive or behavioral characteristics in schizophrenic patients. While smaller amplitudes of several ERP-components have been repeatedly reported for schizophrenic patients versus control groups, a larger slow surface-negative potential following the completion of a forewarned (motor or cognitive) response, called postimperative negative variation (PINY), has been reliably found in schizophrenic patients by several authors, but only rarely in healthy subjects. In a series of studies we examined contributions to the PINY by varying task-related features in visual and auditory delayed-matching-to-sample tasks in groups of schizophrenic patients (DSM-II1-R) and healthy controls. While demands on working memory enhanced PINY amplitude primarily in schizophrenic patients, PINV amplitude increased with ambiguity of the matching in controls and schizophrenics alike. Differential effects of ambiguity and performance requirements (Go-NoGo) on PINY amplitude and its scalp distribution suggest that performance uncertainty contributes to PINV generation and that the threshold for performance uncertainty is reduced in schizophrenics. Topographical analyses suggest that the PINY is generated symmetrically in the frontal lobes in schizophrenics, while it shows a right frontal dominance in controls. Research was supported by the Deutsche Forschungsgemeinschaft (Ro 805).