Increased ratios of homocysteine/vitamin B12, homocysteine/folate and methionine/vitamin B12 in schizophrenic patients

Homocysteine (HCY) and other mediators of one-carbon metabolism have been blamed for the etiology of schizophrenia for a long time. The present study aimed to analyze the serum levels of HCY, methionine (MTY), vitamin-B12 (V-B12), folate (FLT), and glutathione (GSH) in schizophrenic patients and to search for new clues about the etiopathogenesis of this disease. The study included 62 schizophrenic patients (26 females and 36 males with a mean age of 33.79 ± 8.23 years) and 57 healthy control subjects (23 females and 34 males with a mean age of 33.66 ± 8.67 years). The serum levels of HCY and MTY were established using the LC/MS-MS method and the serum levels of V-B12, FLT and GSH were established using the ELISA method. The serum levels of HCY and MTY were significantly higher in the schizophrenia group compared to the control group. Again, the serum ratios of HCY/V-B12, HCY/FLT and MTY/V-B12 were significantly higher in the schizophrenia group than the control group. On the other hand, the serum levels of GSH and V-B12 were significantly lower in schizophrenic patients. The correlation analysis between V-B12 and HCY revealed a stronger negative correlation between HCY and V-B12 in schizophrenic patients than control group (r =–0.491, p < 0.001 for schizophrenic patients; r =–0.286, p = 0.03 for the control group). The present study is the first to evaluate the ratios of HCY/V-B12, HCY/FLT and MTY/V-B12 in schizophrenic patients. A defect in the V-B12 metabolism may increase the serum levels of HCY and MTY in schizophrenic patients.