Genetic Expression in Schizophrenics Treated With SSRI Augmentation: Relationship to Clinical and Cognitive Function

Overview

In our study we aim to examine the effect of SSRI augmentation on negative symptoms and cognitive function in schizophrenia patients as well as to examine the effect of SSRI augmentation on the RNA and protein products in peripheral mononuclear cells (PMC). Finally, we aim to relate changes in PMC elements to changes in clinical symptoms and cognitive function. Our study hypotheses are that SSRI augmentation of anti-psychotic treatment in schizophrenia patients will improve negative symptoms as well as cognitive symptoms and that this improvement will be related to biochemical changes identifiable in PMC elements.

Clinical studies have shown that adding selective serotonin reuptake inhibitor (SSRI) antidepressants to antipsychotics can improve negative symptoms of schizophrenia in patients unresponsive to antipsychotics alone (Silver and Nassar, 1992; Spina et al., 1994; Goff et al., 1995). However, the effect of SSRI augmentation on cognitive impairments of the illness has not been adequately tested. The mechanism of SSRI augmentation is not known and is the focus of research interest. We have recently shown that in animals, combined treatment of SSRI antidepressant and antipsychotic drug resulted in biochemical changes, different from the effects of the individual medications. Changes unique to the combined treatment were found in GABAergic components (GABA-Aβ3 receptor, glutamic acid decarboxylase 67 and PKCβ (Chertkow et al., 2005)) and changes unique to the combined treatment were found in selected areas of rat brain. Studies of drug mechanisms in humans have utilized blood products and PMC which are readily accessible and may reflect molecular processes in the central nervous system (CNS) of schizophrenic patients (Kronfol and Remick, 2000; Avissar et al., 2001; Ilani et al., 2001; Rothermundt et al., 2001). In a recent study (Chertkow et al., 2007) which examined the gene expression profile of PMC's from antipsychotic-treated patients before the addition of the SSRI fluvoxamine, we found that mRNA expression of chemokine receptors, IL8RA and CCR1, and of RGS7 was significantly down-regulated following fluvoxamine augmentation. Additionally, the clinical assessments showed improvement in negative symptoms following the combined treatment. These findings suggested that gene expression changes in PMC's may be useful in investigating the mechanism of drug action in schizophrenia. In this study we will examine RNA and protein expression in the course of fluvoxamine augmentation treatment. 15 chronic schizophrenic patients who have persistent negative symptoms and cognitive impairment despite adequate treatment will participate. Fluvoxamine 100mg/day will be added to the treatment regimen and continued for 6 weeks. Clinical state will be assessed using validated rating scales and cognitive performance will be assessed with a cognitive test battery. Blood samples will be taken at baseline and at 1, 3 and 6 weeks. The PMC's will be assayed using microarray, RT PCR and proteomic techniques. Changes in RNA and protein expression will be detected and compared with changes in clinical symptoms and cognitive function. Identification of biochemical changes related to augmentation treated and their relation to symptomatic and cognitive changes will be the major potential benefit of the study.