Question:
Familial Alzheimer's disease and vitamin B12 deficiency.

A kindred with autosomal dominant familial Alzheimer's disease in whicha mutation results in a valine to glycine substitution at amyloidprecursor protein codon 717 has recently been described. Individuals inthis pedigree were studied retrospectively and prospectively, toevaluate the relationship, if any, between Alzheimer's disease andvitamin B12 deficiency. The presence of Alzheimer's disease was foundto be associated with lower serum vitamin B12 values compared withunaffected family members. There were no significant differencesbetween macrocytosis, the presence of anaemia, serum folate or red cellfolate between affected and unaffected family members. The implicationsof this finding are discussed with regard to previous descriptions ofan association, and in relation to the clinical features of thisparticular kindred.

What's your opinions and can anyone share with me some more information???

Answer: The methyl cycle is also involved in serine and glycine metabolism.NMDA receptors have a glycine binding site which apparently also bindsserine. Some AD drugs that bind this site have been used to increasecognitive function in AD patients

The amino acid D-serine (D-Ser), previously recognized as apharmacological tool for potentiating neuronal activity mediated by theN-methyl-D-aspartate (NMDA) receptor complex, in vitro and in vivo, hasbeen observed in several brain regions of the rat and mouse, mostprominently in cortex. In addition to reconfirming the presence anddistribution of D-Ser in rat brain, we have observed, for the firsttime, endogenous, free D-Ser in temporal cortex of normal human brainsat a level of 2.18 +/- 0.12 nmol/mg of protein, representing 15 +/- 2%of the free L-Ser pool. The D- and L-Ser specific content and theD/L-Ser ratio obtained from temporal cortex of Parkinson and Alzheimerbrains did not differ significantly from those of controls. However, atthe levels observed here, and considering its specificity and affinityfor the NMDA-associated glycine receptor, endogenous D-Ser is aplausible NMDA receptor glycine site agonist.