[Neurological manifestations in Vitamin B 12 deficiency].

Vitamin B-12 deficiency is a common problem encountered in developing countries of the world. In Europe and North America it is frequently encountered in the elderly and in people whose diets are compromised such as alcoholics. Recent data has shown that cobalamin deficiency may occur in 5% to 40% of the general population. The prevalence as stated earlier is higher in the elderly and in nursing home residents. Vitamin B-12 deficiency may take decades to develop and patients may be asymptomatic or may present with a wide spectrum of hematological and neuropsychiatric manifestations. The history of research in Vitamin B-12 deficiency is fascinating and the noble prize has been awarded twice to investigators involved in it.