Visual memory plays an important role in daily life of general population and in patients with schizophrenia. Two functional single nucleotide polymorphisms (SNPs), Ser704Cys of the DISC1 gene and M24 of the G72 gene, are strongly associated with pathogenesis of schizophrenia. This is the first genetic study on visual memory in humans. It examined the interactions of the two SNPs and visual learning (delayed visual memory) in patients with schizophrenia.
Methods
Two hundred seventy-one patients with chronic schizophrenia, stabilized with antipsychotic treatment for > 3 months, were assessed for verbal (word list) and visual memory (visual memory reproduction/visual learning) of Weschler Memory Scale-III (WMS-III), Continuous Performance Test, and genotyped for the DISC1 Ser704Cys SNP and G72 M24 SNP.
Results
Cys/Cys-DISC1 genotype patients had poorer delayed visual memory than the Ser-DISC1 allele carriers (Ser/Ser and Cys/Ser) ( p=0.004, effect size: 0.43), meanwhile no difference was found between patients with G72 M24 A-allele and T/T- G72 M24 genotype (p= 0.590, effect size: 0.07). Patients carrying Ser-DISC1 allele with T/T- G72 M24 genotype had better delayed visual memory than patients carrying Cys/Cys-DISC1 genotype with T/T- G72 M24 genotype (p= 0.004, effect size: 0.70) and with G72 M24 A-allele (p= 0.003, effect size: 0.65). Education had positive effect (p= 0.007) while negative symptoms had negative effect (p=<0.001) on delayed visual memory.
Conclusion
This is the first study associating genetic variation in DISC1 Ser704Cys and G72 M24 with delayed visual memory deficit in patients with chronic schizophrenia.
