High-dose vitamin B6 decreases homocysteine serum levels in patients with schizophrenia and schizoaffective disorders:: A preliminary study

Vitamin B-6 plays an essential role in the normal functioning of the central nervous system. Normal homocysteine (Hcy) serum level is maintained by remethylation of Hey to methionine by enzymes that require folic acid and vitamin B-12 and by catabolism to cysteine by a vitamin B-6-dependent enzyme. These findings may he consistent with the hypothesis that the vitamin B6 status may influence plasma Hey levels. The aims of this preliminary study were (1) to determine whether a correlation exists between Hey and vitamin B6 levels in patients with schizophrenia and schizoaffective disorders and (2) to investigate whether treatment with highdose vitamin B-6 may reduce Hey levels in these patients. Methods: In this preliminary study, we enrolled 11 patients with schizophrenia or schizoaffective disorders (7 men and 4 women; mean age S D, 50 12 years) receiving high doses of vitamin B6 treatment (1200 mg/d) for 12 weeks. Blood samples for the assessment of pyridoxal-5-phosphate and Hey serum levels were obtained at baseline and after 12 weeks of treatment. Results: Age was significantly positively correlated with Hey levels at baseline (r = 0.392, P = 0.004). All other parameters, including diagnosis, disease duration, and pyridoxal-5-phosphate serum level, were not correlated with Hey serum levels at baseline. After vitamin B6 treatment, Hey serum levels significantly decreased (14.2 +/- 3.4 vs. 11.8 +/- 2.0 mu mol/l, respectively, t = 2.679, P = 0.023); this decrease being statistically significant in men but not in women. Conclusions: High doses of vitamin B6 lead to a decrease in Hey serum level in male patients with schizophrenia or schizoaffective disorder.