Risperidone increases the cortical silent period in drug-naive patients with first-episode schizophrenia: A transcranial magnetic stimulation study.

OBJECTIVES: Schizophrenia is accompanied by impaired cortical inhibition, as measured by several markers including the cortical silent period (CSP). It is thought that CSP measures gamma-aminobutyric acid receptors B (GABAB) mediated inhibitory activity. But the mutual roles of schizophrenia as a disease and the drugs used for the treatment of psychosis on GABA mediated neurotransmission are not clear. METHODS: We recruited 13 drug-naive patients with first-episode schizophrenia. We used transcranial magnetic stimulation to assess CSP prior to initiating risperidone monotherapy and again four weeks later. At the same time, we rated the severity of psychopathology using the Positive and Negative Syndrome Scale (PANSS). RESULTS: We obtained data from 12 patients who showed a significant increase in CSP, from 134.20±41.81 ms to 162.95±61.98 ms ( p=0.041; Cohen's d=0.544). After the treatment, the PANSS total score was significantly lower, as were the individual subscores ( p<0.05). However, no correlation was found between ΔCSP and ΔPANSS. CONCLUSION: Our study in patients with first-episode schizophrenia demonstrated an association between risperidone monotherapy and an increase in GABAB mediated inhibitory neurotransmission.

Repetitive transcranial magnetic stimulation reduces cigarette consumption in schizophrenia patients.

INTRODUCTION: High-frequency repetitive transcranial magnetic stimulation (rTMS) over the left dorsolateral prefrontal cortex (DLPFC) seemed to decrease tobacco consumption and craving in nicotine-dependent people without psychiatric disorder or otherwise healthy people. Even if the prevalence of cigarette smoking in schizophrenia patients is high and estimated to be between 45% and 88%, this technique has not been systematically studied in this indication in schizophrenia yet. THE AIM OF THE STUDY: The aim of this study was to test the ability of high-frequency (10Hz) rTMS over the left DLPFC to decrease cigarette consumption in schizophrenia patients. METHODS: The study included 35 male schizophrenia patients on stable antipsychotic medication. The patients were divided into two groups: the first (18 patients) were actively stimulated and the second (17 patients) underwent sham (placebo) stimulation. The sham rTMS was administered using a purpose-built sham coil that was identical in appearance to the real coil and made the same noise but did not deliver a substantial stimulus. The rTMS was administered at the stimulation parameters: location (left dorsolateral prefrontal cortex: DLPFC), intensity of magnetic stimulation in % of motor threshold (110%), stimulation frequency (10Hz), number of trains (20), single train duration (10s), inter-train interval (30s), and total number of stimulation sessions (21). In each stimulation session, 2000TMSpulses were given, with a total of 42,000pulses per treatment course. Patients noted the number of cigarettes smoked in the 7days before treatment, during the whole stimulation treatment (21days), and again for a 7-day period after treatment. RESULTS: Cigarette consumption was statistically significantly lower in the actively stimulated patients than in the sham rTMS group as early as the first week of stimulation. No statistically relevant correlations were found in the changes of ongoing negative or depressive schizophrenia symptoms and the number of cigarettes smoked. CONCLUSION: High-frequency rTMS over the left DLPFC has the ability to decrease the number of cigarettes smoked in schizophrenia patients.

Psychometric properties of the Temperament and Character Inventory-Revised (TCI-R) in Czech adolescent sample.

The psychometric properties of the TCI-R method were investigated in a cohort of 15-year-old adolescents (n = 787). This is the lowest recommended age for using the adult version of the method. A factor analysis of the temperament and character scales was carried out on the basis of Principal Component Analysis with Varimax rotation. We compared our results with a previous TCI version which was used in the pilot study of 15-year-olds (n = 171), with established norms for the Czech adolescents and adults, and in regard to gender differences. The principal component analyses for all scales with eigenvalues ≥ 1 resulted in only a 6 factor structure, in contrast to the 7 factor structure postulated by Cloninger. But the factor solution, computed separately for temperament (4F) and character (3F), approximately reflected the Cloninger's model except for the temperament subscales NS1 (Exploration Excitability), RD1 (Sentimentality) and RD4 (Dependence), which load multiple factors, and the character subscale SD 4 (Self-acceptance), which loads the Cooperativeness factor. The internal consistency of the main TCI-R scales was excellent; the Cronbach's alpha varied from .83 (NS) to .89 (HA). However, for some subscales (NS4, RD4, and CO5) the consistency was rather weak. In our research, the previous version of TCI showed less satisfying psychometric properties than TCI-R did. In terms of gender differences, girls scored higher in NS, RD, HA, CO and ST, whereas boys scored higher in PS; no statistically significant differences for SD were found. In general, our results support the Cloninger's postulated 7 factor personality structure and the appropriateness of the TCI-R usage for 15-year-old adolescents.