Familial Alzheimer's disease and vitamin B12 deficiency

A kindred with autosomal dominant familial Alzheimer's disease in which a mutation results in a valine to glycine substitution at amyloid precursor protein codon 717 has recently been described. Individuals in this pedigree were studied retrospectively and prospectively, to evaluate the relationship, if any, between Alzheimer's disease and vitamin B12 deficiency. The presence of Alzheimer's disease was found to be associated with lower serum vitamin B12 values compared with unaffected family members. There were no significant differences between macrocytosis, the presence of anaemia, serum folate or red cell folate between affected and unaffected family members. The implications of this finding are discussed with regard to previous descriptions of an association, and in relation to the clinical features of this particular kindred.