Vitamin B6 plays an essential role in the normal functioning of the central nervous system. Normal homocysteine (Hcy) serum level is maintained by remethylation of Hcy to methionine by enzymes that require folic acid and vitamin B12 and by catabolism to cysteine by a vitamin B6-dependent enzyme. These findings may be consistent with the hypothesis that the vitamin B6 status may influence plasma Hcy levels. The aims of this preliminary study were (1) to determine whether a correlation exists between Hcy and vitamin B6 levels in patients with schizophrenia and schizoaffective disorders and (2) to investigate whether treatment with high-dose vitamin B6 may reduce Hcy levels in these patients.
In this preliminary study, we enrolled 11 patients with schizophrenia or schizoaffective disorders (7 men and 4 women; mean age ± SD, 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 Hcy serum levels were obtained at baseline and after 12 weeks of treatment.
Age was significantly positively correlated with Hcy 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 Hcy serum levels at baseline. After vitamin B6 treatment, Hcy serum levels significantly decreased (14.2 ± 3.4 vs. 11.8 ± 2.0 μmol/L, respectively, t = 2.679, P = 0.023); this decrease being statistically significant in men but not in women.
High doses of vitamin B6 lead to a decrease in Hcy serum level in male patients with schizophrenia or schizoaffective disorder.