LONDON, UNITED KINGDOM. Dr. E.H. Reynolds, a consulting neurologist at King's College, has produced a comprehensive review of the association between folic acid and neuropsychiatric disorders such as depression and dementia. Dr. Reynolds points out that a folate deficiency is quite common, especially in older people. Severe folate deficiency is associated with megaloblastic anemia and it is estimated that some two thirds of patients with megaloblastic anemia also have a neuropsychiatric disorder. In elderly people a close association has been noted between a folate deficiency and apathy, depression, dementia, withdrawal, and a lack of motivation. In a study of 164 Alzheimer's patients cognitive decline was significantly associated with raised plasma homocysteine levels and lowered folic acid and vitamin B12 levels. Significant improvements were noted in 24 folate-deficient, depressed persons who were given 15 mg/day of folic acid for a four-month period. Other studies have shown that supplementation with as little as 0.5 mg/day of folic acid increases the effectiveness of fluoxetine (Prozac). Dr. Reynolds points out that folic acid can excite the nervous system so should be used with caution in epileptics. It should also be used with caution if a vitamin B12 deficiency is suspected.
Reynolds, E.H. Folic acid, ageing, depression, and dementia. British Medical Journal, Vol. 324, June 22, 2002, pp. 1512-15