Objective: To assess the association of cognitive impairment and clinical symptoms in first-episode schizophrenia with the Val66Met (rs6265) polymorphism of brain-derived neurotrophic factor (BDNF) gene.
Methods: For 87 patients with first-episode schizophrenia and 76 healthy controls, the Val66Met polymorphism was determined with a Taqman Assay-on-Demand method. Wechsler intelligence test was carried out for all participants. Correlation of cognitive impairment with clinical severity was also analyzed.
Results: The patients were significantly lower in total IQ, verbal IQ and performance IQ compared to the controls. The lower total IQ (F=4.59, P= 0.01) and verbal IQ (F=4.44, P=0.01) were influenced by genetic factors and diagnostic interaction. The vertal IQ of Val/Val patients was significantly lower than those of Val/Met and Met/Met carriers. For the control group, the verbal IQ of Met/Met carriers was lower than that of Val/Met carriers, and the total IQ of Met/Met carriers was lower than those of Val/Met and Val/Val carriers. For the patient group, the total IQ of Val/Val carriers was negatively correlated with positive symptoms (r=-0.65, P=0.03) and thought disorders (r=-0.61, P=0.02).
Conclusion: Cognitive impairment in first-episode schizophrenic patients is associated with the Val66Met polymorphism of the BDNF gene, and has an important clinical relevance.