The cobalamin status was evaluated in Alzheimer dementia (n = 26), other dementias (n = 24), various gerontopsychiatric disorders (n = 25), and in neuro-psychiatrically healthy controls (n = 20). Supplementing serum cobalamin we measured methylmalonic acid (MMA), a metabolite accumulating early in cobalamin deficiency. Subnormal cobalamin and/or clearly elevated MMA concentrations were found in 11 cases: 7 Alzheimer patients (27%), 2 with other dementias (8%), one psychiatric patient (4%), and one control (5%). None presented the typical neurologic features of cobalamin deficiency and macrocytosis was found in only one. The mean cobalamin concentration was significantly lower in Alzheimer patients (179 +/- 18 pmol/l) than in the age-matched controls (256 +/- 23 pmol/l) (p = 0.013) and the other patient groups. Correspondingly, the mean MMA level was higher in the Alzheimer group (0.480 +/- 0.062 mumol/l) than in any other diagnostic group (controls: 0.347 +/- 0.040 mumol/l). Comparing the Alzheimer group to the other groups as a whole, the elevation was significant (p = 0.0097). Our findings indicate that Alzheimer patients are particularly prone to cobalamin deficiency, and even subtle biochemical signs of deficiency seem to justify treatment.
Kristensen MO, Gulmann NC, Christensen JE, Ostergaard K, Rasmussen K. Serum cobalamin and methylmalonic acid in Alzheimer dementia. Acta Neurol Scand 1993 June University Department of Neurology, Aarhus Kommunehospital, Denmark.