Obsessive compulsive symptoms are associated with better functioning independently of cognition in schizophrenia.

OBJECTIVES: Although the relationship of obsessive-compulsive symptoms (OCSs) with both cognition and social functioning (SF) has already been the focus of research in schizophrenia, the moderation of the relationship of OCSs with SF by cognition has not been explored to date. We investigated the association of OCSs with SF and its interaction with cognition in schizophrenia. METHODS: We recruited 110 schizophrenia patients and assessed OCSs (Yale-Brown Scale), schizophrenia symptoms (Positive and Negative Syndrome Scale), SF (Strauss-Carpenter Scale) and cognition. 51 patients had one obsessive-compulsive symptom or more, whereas 59 patients had no obsessive compulsive-symptom, according to the Yale-Brown Scale. We mainly investigated: a) the predictive effect of OCSs on SF, controlling for cognition, illness duration and symptoms' severity and b) the moderating effect of cognition on the OCSs-SF relationship. RESULTS: The mean score of OCSs for patients having at least one symptom was 13.43 (SD=8.32). Higher OCSs predicted increased SF (B=0.98, t=2.41, df=88, p=0.018). This relationship was driven by the association of compulsions with job functioning (B=0.074, t=2.029, df=88, p=0.046). Patients without OCSs demonstrated worse functioning compared with those having at least one obsessive-compulsive symptom (mean difference=2.496, t=3.732, df=88, p<0.001). We failed to find evidence that cognition moderates the effect of OCSs on SF. CONCLUSION: There may be a beneficial effect of OCSs on SF in patients with schizophrenia which is independent of their cognitive performance.

COMT and MTHFR polymorphisms interaction on cognition in schizophrenia: an exploratory study.

The investigation of the catechol-O-methyltransferase (COMT-[rs4680]) and methylenetetrahydrofolate reductase (MTHFR-[rs1801133]) polymorphisms' interaction might shed light into the pathogenetic mechanisms of the cognitive dysfunction in schizophrenia. In an exploratory study, we hypothesized that the MTHFR 677T allele which has been related to a hypoactive MTHFR enzyme would augment the unfavorable effects of COMT Val158 homozygosity which has been associated with COMT enzyme hyperfunction. 90 schizophrenia patients and 55 healthy volunteers were assessed on psychomotor speed, pattern and spatial recognition memory (SRM), spatial working memory (SWM), attentional flexibility and planning (Stockings of Cambridge-SOC). IQ scores in a random subgroup of patients were also measured. A significant COMT×MTHFR interaction on SWM (p=0.048) and planning (p=0.026) was revealed in both groups. Among COMT-Val/Val participants, MTHFR-C/C made more SWM errors (p=0.033) and solved fewer SOC problems (p=0.025) than MTHFR-T carriers. In patients, there was a significant COMT×MTHFR interaction on full scale IQ (p=0.035): among COMT-Met carriers, MTHFR-T carriers performed significantly worse than MTHFR-C/C (p=0.021), which was driven by a COMT×MTHFR interaction involving performance IQ (p=0.047). In conclusion, COMT and MTHFR polymorphisms interacted on cognition, suggesting that the MTHFR enzyme activity might moderate the effects of the COMT enzyme. In contrast to our initial hypothesis, the MTHFR T-allele attenuated the cognitive effects of COMT Val homozygosity. In this preliminary study, we propose that dopaminergic and intracellular methylation mechanisms could interact on cognitive deficits in schizophrenia.

Doubtful association of antipsychotic polypharmacy and high dosage with cognition in chronic schizophrenia.

Despite consistent recommendations for antipsychotic monotherapy, antipsychotic polypharmacy (the use of two or more antipsychotic agents) and the administration of excessive doses (higher than 1000 mgr/day of chloropromazine equivalents) is a common practice in schizophrenia. The therapeutic and adverse effects of this practice are poorly studied, in particular with regards to the cognitive symptoms of the disease. In this cross-sectional study we investigated the cognitive effects of antipsychotic polypharmacy and excessive doses in 53 patients with chronic schizophrenia using non-verbal cognitive tasks involving speed of movement, memory and executive functions. No significant difference in performance scores was found between the groups under polypharmacy and monotherapy, or the groups receiving either excessive or normal doses of antipsychotics. Since these groups did not also differ in demographic, clinical, other pharmacologic parameters, in the relative anticholinergic potency of antipsychotics, or in intelligence scores, we raise doubts about the association of polypharmacy and excessive doses with non-verbal cognitive performance in chronic schizophrenia.