The quality of clinical research in this area is improving, but there are many unanswered questions that affect clinical practice. Clinicians should remain vigilant to the possibility of deficiencies of folate and cobalamin in diverse psychiatric populations. Normal hematological indices do not rule out the deficiencies. Further study is needed to refine the detection and clinical management of these vitamin deficiencies in psychiatric populations. A relationship between folate and neuropsychiatric disorders has been inferred from clinical observation and from the enhanced understanding of the role of folate in critical brain metabolic pathways.
Depressive symptoms are the most common neuropsychiatric manifestation of folate deficiency.
Recently, low folate levels have been linked to poorer antidepressant response to selective serotonin reuptake inhibitors. Factors contributing to low serum folate levels among depressed patients as well as the circumstances under which folate and its derivatives may have a role in antidepressant pharmacotherapy must be further clarified. 90 Folate, vitamin B12, and neuropsychiatric disorders. Folate and vitamin B12 are required both in the methylation of homocysteine to methionine and in the synthesis of S-adenosylmethionine. S-adenosylmethionine is involved in numerous methylation reactions involving proteins, phospholipids, DNA, and neurotransmitter metabolism.