Cobalamin/folate status and its relation to cognition and behaviour in psychogeriatric patients.

The aim of this study was to evaluate the diagnostic potentials of four different biochemical markers, serum cobalamin, blood folate, plasma homocysteine and serum methylmalonic acid for diagnosis of cobalamin/folate deficiency in a psychogeriatric population. The second aim was to investigate the relationship between these markers and various clinical and functional parameters of the nervous system in patients with dementia disorders. The concentration of plasma homocysteine was increased and elevated in about 40-50 % of the psychogeriatric patients, while the concentrations of serum cobalamin and serum methylmalonic acid were not changed. The concentration of blood folate was significantly decreased in patients with dementia. Both plasma homocysteine and serum methylmalonic acid normalised when the patients received cobalamin/folate supplementation. The extent of the decrease of the markers was associated with the degree of tissue deficiency of cobalamin. Plasma homocysteine and blood folate concentrations correlated significantly with the severity of dementia and symptoms indicating cognitive impairment and delirium, such as memory impairment, disorientation and clinical fluctuations. There was no such relation between concentration of serum cobalamin and serum methylmalonic acid and any of those clinical parameters. Cobalamin/folate supplementation improved cognitive functions only in patients with elevated plasma homocysteine levels. Clinical improvement after cobalamin supplementation was related to changes in the regional cerebral blood flow. The study indicates that plasma homocysteine is the best marker, out of those investigated, for detection of cobalamin/folate deficiency in psychogeriatric patients.