FOLATE, VITAMIN-B-12, AND NEUROPSYCHIATRIC DISORDERS

Folate and vitamin B-12 are required both in the methylation of homocy steine to methionine and in the synthesis of S-adenosylmethionine. S-a denosylmethionine is involved in numerous methylation reactions involv ing proteins, phospholipids, DNA, and neurotransmitter metabolism. Bot h folate and vitamin B-12 deficiency may cause similar neurologic and psychiatric disturbances including depression, dementia, and a demyeli nating myelopathy. A current theory proposes that a defect in methylat ion processes is central to the biochemical basis of the neuropsychiat ry of these vitamin deficiencies. Folate deficiency may specifically a ffect central monoamine metabolism and aggravate depressive disorders. In addition, the neurotoxic effects of homocysteine may also play a r ole in the neurologic and psychiatric disturbances that are associated with folate and vitamin B-12 deficiency.