Evaluation of hyperhomocysteinemia prevalence and its influence on the selected cognitive functions in patients with schizophrenia.

There is evidence that hyperhomocysteinemia may be associated with the development of schizophrenia and cognitive impairment. Therefore, the aim of this study was to analyze the relationship between cognitive functions and normal homocysteine concentrations vs. hyperhomocysteinemia in schizophrenia patients before and after supplementation with vitamins B6, B12 and folate. An 8-week prospective, non-randomized study enrolled 122 adult patients with schizophrenia (67F/55M, mean age 43.54 ± 11.94 years). Homocysteine concentrations were measured in all individuals and afterwards hyperhomocysteinemia patients (n = 42) were divided into two subgroups: treated with oral vitamins supplementation (B6 - 25 mg/d, B12 - 20 μg/d, folate - 2,5 mg/d) (n = 22) and without supplementation (n = 20). The assessment of schizophrenia symptoms severity in study group was performed using the Positive and Negative Syndrome Scale (PANSS). Cognitive functions were evaluated using the Stroop test and the Trail Making Test (TMT). We observed a higher prevalence of hyperhomocysteinemia in schizophrenia patients (34.4%) in comparison to the general population. Individuals with schizophrenia and coexisting hyperhomocysteinemia had worse performance on the Stroop and the TMT tests as well as higher PANSS scores. In these patients, supplementation with vitamins effectively decreased the homocysteine concentrations to the normal values, however there was no statistically significant improvement in the PANSS and cognitive test scores, except a significant decrease in the number of the Stroop test errors. We conclude that significant results obtained in this study show that there is a relationship between homocysteine blood concentration and schizophrenia severity. Moreover, homocysteine concentration lowering might be beneficial in schizophrenia patients with hyperhomocysteinemia in terms of cognitive functions improvement.