HOMOCYSTEINEMIA AND SCHIZOPHRENIA AS A CASE OF METHYLATION DEFICIENCY

A 27-year-old woman is described whose disorder meets the DSM-III-R cr iteria for a diagnosis of schizophrenia and who was found to have a si gnificantly increased serum level of homocysteine. Repeatedly, she imp roved on frequent cobalamin injections and deteriorated in periods wit hout treatment. The effects of prolonged weekly treatment appeared to diminish as time went on, suggesting that the abnormality was not whol ly cobalamin-dependent. It was found that methylenetetrahydrofolate re ductase (MR) activity in cultured skin fibroblasts was reduced to a ma gnitude that is found among people with heterozygous deficiency. A def ect in MR activity indicates a deficiency in methyltetrahydrofolate (M THF), with a consequent reduction of the remethylation of homocysteine to methionine. Thus, reduced methylation may explain the increased le vels of homocysteine and the transient effects of cobalamin treatment in the patient. Theoretically, MTHF should be the optimal treatment fo r her. The case reported highlights the importance of assessing the se rum homocysteine level in order to detect methylation deficiency in pa tients with schizophrenia.