TCF4 gene polymorphism and cognitive performance in patients with first episode psychosis

Background: Single nucleotide polymorphisms in TCF4 gene have been consistently associated with schizophrenia in genome wide association studies, including the C allele of rs9960767. However, its exact role in modulating the schizophrenia phenotype is not known. Aims: To comprehensively investigate the relationship between rs9960767 risk allele (C) of TCF4 and cognitive performance in patients with first episode psychosis (FEP). Methods: 173 patients with FEP received a comprehensive neurocognitive evaluation and were genotyped for rs9960767. Carriers of the risk allele (CA/CC) were compared to non-carriers (AA) using Multivariate Analysis of Covariance MANCOVA. Ethnicity, negative symptoms and substance abuse were included as covariates. Results: Carriers of the risk allele had a statistically significant lower performance in the cognitive domain of Reasoning/Problem-Solving compared to non-carriers (F_1,172=4.4, p=.038). There were no significant genotype effects on the other cognitive domains or general cognition. This effect on the Reasoning/Problem-Solving domain remained significant even when controlling for IQ (F_1,172=4.3, p=.039). Conclusions: rs9960767 (C) of TCF4 appears to be associated with neurocognitive deficits in the Reasoning/Problem-Solving cognitive domain, in patients with FEP. A confirmation of this finding in a larger sample and including other TCF4 polymorphisms will be needed to gain further validity of this result.