Performance on the Wisconsin Card Sorting Test in schizophrenia and genes of dopaminergic inactivation (COMT, DAT, NET)

The aim of the study was to test an association between polymorphisms of genes connected with dopaminergic inactivation in prefrontal cortex [catechol-O-methyltransferase (COMT), dopamine transporter (DAT), norepinephrine transporter (NET)], and performance on the Wisconsin Card Sorting Test (WCST), in schizophrenic patients. The number of perseverative errors (WCST-P), non-perseverative errors (WCST-NP), completed corrected categories (WCST-CC), conceptual level responses (WCST-%CONC) and set to the first category (WCST-1st CAT) were measured. Genotyping was done for the Val108(158)Met polymorphism of the COMT gene (79 patients), the 3′UTR VNTR polymorphism of the DAT gene (124 patients) and the 1287 A/G polymorphism of the NET gene (63 patients). Male schizophrenic patients with Val/Val genotype of COMT obtained better results on WCST-P, while female patients had worse results on the WCST-NP compared with the remaining genotypes. There was a slight trend for patients with the A9/A9 genotype of DAT and with the A/A genotype of NET to perform better on some domains of the WCST, compared with other genotypes. A limitation to the interpretation of results could be small number of patients studied as well as variable psychopathological state and medication during cognitive testing.