Cognitive impairment in schizophrenia is a core feature and seems to be related mainly to dopaminergic dysfunction in the prefrontal cortex (PFC). The functional polymorphism Val158Met of the COMT (catechol-O-methyltransferase) gene could mediate the relationship between cognition and dopamine activity in PFC. The present study tested the influence of this polymorphism on the cognitive performance of schizophrenia spectrum patients and their relatives, using some subtests of the neuropsychological battery, the Measurement and Treatment Research to Improve Cognition in Schizophrenia (MATRICS) Consensus Cognitive Battery, and evaluated the impact of this polymorphism on a specific prefrontal cognitive function using a cognitive neuroscience paradigm. A Group of 74 schizophrenia spectrum disorder patients, 48 relatives and 67 controls performed some subtests of the MATRICS Consensus Cognitive Battery. In addition, 40 schizophrenia spectrum disorder patients, 26 relatives and 63 controls performed the Dot Pattern Expectancy Task (DPX) to study context processing. For the neuropsychological battery, no differences in any of the cognitive domains were found according to genotype. The DPX task was sensitive to genotype effects in patients as well as in relatives. Context processing deficits in schizophrenia patients and their relatives may be mediated by COMT genotype. The influence of the COMT genotype on cognition is more relevant in specific cognitive tasks related to prefrontal function. These results should be replicated in larger samples.
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