[Homocysteine and methylmalonic acid as markers of cobalamin/folate status. The association to neuropsychiatric symptoms in the elderly is explored].

Cobalamin/folate deficiency in elderly subjects may lead to psychiatric symptoms. Most studies concerning the relation between mental disorders in the elderly and deficiencies of cobalamin and folate have used methods that determine the blood concentrations of these vitamins, which might not reflect vitamin status in the tissues. Two new markers, plasma homocysteine and serum methylmalonic acid, have attracted growing interest since they are considered to reflect the functional status of cobalamins and folates in the tissues. This review summarizes present findings concerning the different markers for cobalamin/folate deficiency as well as their association with functional parameters of the central nervous system such as cognitive and behavioral performance. Plasma homocysteine seems to be much more closely associated with neuropsychiatric dysfunction than is plasma methylmalonic acid.