Absence of macrocytic anaemia in Alzheimer's disease.

There is an association between Alzheimer's disease (AD) and low serum levels of vitamin B12 and folic acid. Patients also have elevated serum levels of homocysteine and disease progression might therefore be associated with the development of a macrocytic anaemia. We investigated the relationship between disease duration, homocysteine and haematological indices in patients with clinically diagnosed AD and healthy elderly controls. Haemoglobin and platelet counts fell only slightly with increasing dementia duration, but there were no other changes in haematological indices. In particular, macrocytosis and red cell distribution width were unrelated to disease duration and no patients were anaemic. Our results support previous observations that the neurological and haematological features of B12 and folate deficiency are often unrelated in these patients.