SNAP-25 gene polymorphisms and weight gain in schizophrenic patients.

Drug induced weight gain is a serious side effect of several atypical antipsychotics. As genetic factors play an important role in the homeostasis of hunger/satiety we tried to replicate a preliminary previous finding about an impact of three polymorphisms in the synaptosomal-associated protein of 25kDa (SNAP-25; sites MnlI, TaiI and DdelI in the 3(')-UTR) on clinical response and antipsychotic induced weight gain. We genotyped 162 schizophrenic patients being treated in monotherapy with atypical antipsychotics and 312 healthy control subjects for the three polymorphisms in the SNAP-25 gene using PCR. PANSS scores and weight were measured weekly for a minimum of five weeks. We found significant associations between the TaiI and MnlI polymorphisms and serum triglyceride levels at baseline and for the DdelI polymorphism and weight gain. In conclusion our study can at least partly replicate the previous findings concerning the impact of SNAP-25 gene polymorphisms on weight gain during antipsychotic treatment.

Investigating disease susceptibility and the negative correlation of schizophrenia and rheumatoid arthritis focusing on MIF and CD14 gene polymorphisms.

Schizophrenia and rheumatoid arthritis (RA) are both chronic diseases with an estimated genetic component of 60%. While RA is a well-known autoimmune inflammatory joint disease, recent data point to an active immune process also being involved in schizophrenia. Several studies confirmed the negative association between schizophrenia and RA, indicating genetic factors that predispose to the one disorder, while protecting from the other. Macrophage migration inhibitory factor (MIF) and the monocytes surface receptor CD14 are involved in the development and maintenance of chronic inflammation. We therefore investigated if the -G173C single nucleotide polymorphism (SNP) and the tetranucleotide repeat CATT (5 - 8) at position -794 of the MIF gene and the CD14 - C159T transition are candidates for genetic liability to schizophrenia and RA or could explain the negative association between them. In our study 157 schizophrenic patients, 119 patients suffering from RA, and 225 healthy individuals were genotyped. All subjects were Caucasians. The CD14- and MIF-genotypes were equally distributed in all three groups. From our results, we cannot confirm the hypothesis that the investigated genetic mutations within the MIF and/or the CD14 gene are involved in the aetiology of either disease or could explain the negative correlation of schizophrenia and RA.

Associations of SNAP-25 polymorphisms with cognitive dysfunctions in Caucasian patients with schizophrenia during a brief trail of treatment with atypical antipsychotics.

The synaptosomal-associated protein of 25 kDa (SNAP-25) is part of the soluble N-ethylmaleimide-sensitive fusion protein (NSF) attachment receptor (SNARE), which mediates synaptic neurotransmission. In earlier studies a possible involvement of this protein in schizophrenia has been shown. As neurocognitive impairment is a core feature in the pathology of schizophrenia and considered to be a putative endophenotype according to genetic studies we investigated the influences of different SNAP-25 polymorphisms on neuropsychological test results before and during treatment with atypical antipsychotics. A total of 104 schizophrenic patients treated with atypical antipsychotics were genotyped for three different polymorphisms of the SNAP-25 gene (MnlI, TaiI and DdeI in the 3'-UTR). Cognitive function was assessed at baseline, week 4 or 6 and week 8 or 12. Results of individual neuropsychological tests were assigned to six cognitive domains (reaction time and quality; executive function; working, verbal and visual memory) and a general cognitive index. The MnlI and TaiI polymorphisms showed no associations to deficits on neuropsychological test results. In contrast, we observed a significant relation between the DdeI polymorphism of the SNAP-25 gene and cognitive dysfunctions. Homozygote T/T allele carriers of the DdeI polymorphism showed significant better neuropsychological test results in cognitive domains verbal memory and executive functions than those with the combined T/C and C/C genotypes (P < 0.01) at all three time points, but no differences in response to treatment with atypical antipsychotics. Additionally, TT carriers exhibited significantly better results in a general cognitive index (P < 0.05). As we observed an association between the DdeI polymorphism of the SNAP-25 gene and cognitive dysfunctions of schizophrenic patients our finding suggests that the SNAP-25 gene could play a role in the pathophysiology of neurocognitive dysfunctions in schizophrenia but is not predictive for treatment response with atypical antipsychotics.

Efficacy of olanzapine versus quetiapine on cognitive dysfunctions in patients with an acute episode of schizophrenia.

Neurocognitive impairment is a core feature in the pathology of schizophrenia and considered to be relatively persistent towards psychopharmacological interventions. There are hints that atypical antipsychotics can influence neurocognitive dysfunctions more favorable than conventional compounds. But little is known about differences in efficacy on neurocognitive dysfunctions linked to the variety of receptor profiles of different atypical antipsychotics. This study compared the effects of the atypical antipsychotics quetiapine and olanzapine on cognitive function in patients with an acute episode of schizophrenia. Patients were randomized to receive quetiapine or olanzapine for 8 weeks. Cognitive function was assessed at baseline, week 4 and week 8. Efficacy was assessed weekly using the Positive and Negative Syndrome Scale (PANSS) and the Clinical Global Improvement Scale (CGI). Tolerability was assessed each week using the Extrapyramidal Symptom Rating Scale (ESRS), the Barnes Akathisia Scale (BAS) and the Udvalg for Kliniske Undersogelser Side Effect Rating Scale (UKU). In total, 52 patients were enrolled in the study. Data from the 33 patients who completed cognitive assessments at two or more time points out of three (baseline, Week 4 and Week 8) are analyzed here. Both quetiapine and olanzapine improved global cognitive index z-scores, however, this was more marked with quetiapine. Between-group comparisons showed significantly greater improvements in reaction quality/attention with quetiapine than olanzapine. Quetiapine and olanzapine produced significant improvements from baseline to week 8 in PANSS total and subscale scores. Both treatments were well tolerated, especially no EPS occurred during 8 weeks of treatment. Both quetiapine and olanzapine improved cognition; however, the improvement in cognitive index scores was more marked in patients receiving quetiapine. Furthermore, quetiapine produced a significantly greater improvement in reaction quality/attention than olanzapine.

Effects of risperidone and quetiapine on cognition in patients with schizophrenia and predominantly negative symptoms.

Evidence suggests that neurocognitive impairment is a key factor in the pathology of schizophrenia and is linked with the negative symptoms of the disease. In this study the effects of the atypical antipsychotics quetiapine and risperidone on cognitive function in patients with schizophrenia and with predominantly negative symptoms were compared. Patients were randomly assigned to double-blind treatment with quetiapine or risperidone for 12 weeks. Cognitive function was assessed at baseline, Week 6 and Week 12. Efficacy was assessed using the Positive and Negative Syndrome Scale (PANSS) and the Scale for the Assessment of Negative Symptoms (SANS) at baseline, Week 6 and Week 12. Extrapyramidal side-effects were assessed each week using the Simpson-Angus Scale (SAS), adverse events were recorded as additional indicators of tolerability throughout the trial. In total, 44 patients were enrolled in the study. Data from the 34 patients who completed cognitive assessments at two or more time points out of three (baseline, Week 6 and Week 12) are analysed here. Quetiapine improved significantly global cognitive index z-scores at both Week 6 (p<0.001 vs. baseline) and Week 12 (p<0.01 vs. baseline), whereas risperidone improved significantly global cognitive index z-scores at Week 12 (p<0.05). Between-group comparisons at Week 6 showed significantly greater improvements in working memory and verbal memory with quetiapine than risperidone (p<0.05) and a significantly greater improvement in reaction quality/attention with quetiapine than risperidone at Week 12 (p<0.05). Quetiapine and risperidone produced significant improvements from baseline in PANSS total (p<0.001) and subscale scores at Week 12. Significant improvements in SANS total score were also seen in both the quetiapine (p<0.001) and risperidone (p<0.01) groups at Week 12 compared with baseline. SAS scores, measuring the incidence of extrapyramidal side-effects, were higher in patients receiving risperidone compared with those receiving quetiapine, and significant differences were seen at Weeks 3, 4, 5 and 7. Both quetiapine and risperidone improved cognition according to changes in cognitive index scores from baseline to Week 12. These results suggest that quetiapine and risperidone provide valuable treatment options for patients with schizophrenia with predominantly negative symptoms. Also, the improvements in cognition following treatment with quetiapine and risperidone may enhance long-term outcomes for these patients.

IL-2 and IL-4 polymorphisms as candidate genes in schizophrenia.

An immune process, characterized by a relative predominance of the T helper-2 (Th2) system and possibly induced by a viral infection,may be involved in the pathophysiology of schizophrenia. In this context, functional polymorphisms in the Interleukin-2 (IL-2) and Interleukin-4 (IL-4) genes appear to be principal candidates for genetic schizophrenia research. Further evidence for these candidate genes comes from several linkage analyses, pointing to susceptibility gene loci on chromosomes 4q and 5q, where the genes coding for IL- 2 and IL-4 are located. We carried out a case-control study including 230 schizophrenic patients and 251 healthy persons, investigating the IL-2 -330 T/G single nucleotide polymorphism (SNP) and the IL-4 -590 C/T SNP. A significant association of the IL-2 -330 TT genotype and of the IL-4 -590 CC genotype with schizophrenia could be identified. Our findings may partly account for the relative predominance of the Th2 system in schizophrenia, although they cannot directly explain this immunological imbalance, but may be related to an altered antiviral immune response in patients with schizophrenia.

Quetiapine has equivalent efficacy and superior tolerability to risperidone in the treatment of schizophrenia with predominantly negative symptoms.

Atypical antipsychotics are generally thought to be more effective than conventional agents in treating the negative symptoms of schizophrenia; however, there have been few direct comparisons among atypicals. We therefore investigated risperidone and quetiapine with respect to their efficacy against negative symptoms in a 12-week,double-blind, comparative pilot study involving 44 patients with schizophrenia with predominantly negative symptoms, as defined by Positive and Negative Syndrome Scale (PANSS) scores. Other efficacy measures included the Scale for the Assessment of Negative Symptoms (SANS) and the Clinical Global Impression (CGI) rating scale. Antipsychotic tolerability was assessed using the Simpson-Angus Scale (SAS) and various laboratory measures. Mean doses were 589.7 mg/ day quetiapine and 4.9 mg/day risperidone (observed cases). Both antipsychotics produced significant decreases in PANSS total, positive and negative scores, and SANS scores. Patients receiving risperidone were significantly more likely to experience extrapyramidal symptoms (EPS) [p <0.05], or to require anticholinergic medication (p <0.05), and had significantly higher prolactin levels (p <0.001) than quetiapine-treated patients. In conclusion, there is no significant difference in efficacy between quetiapine and risperidone in alleviating the negative symptoms of schizophrenia. Quetiapine is also well tolerated, with a lower incidence of EPS and prolactin increase than risperidone.