OBJECTIVETo observe the correlation between the decline of cognitive function and the level of plasma homocysteine in patients with Alzheimer's disease (AD).

METHODSThirty six AD patients were selected from hospitals in Tianjin. The enrolled patients were in accord with the diagnosis criteria. Thirty two control subjects were corresponding patients without AD in the period. Blood samples were extracted from each subject to determine the levels of homocysteine (Hcy) and folate. Cognitive status was evaluated by the mini- mental state examination (MMSE) and clinical dementia rating scale (CDR).

RESULTSThe mean value of serum Hcy concentration [(17.51 +/- 5.62) micromol/L] of AD group was higher than that of control group [(12.38 +/- 4.25)micromol/L]. The serum [(5.17 +/- 1.76) microg/L] and diet folate [(206.94 +/- 44.51) microg/d] concentration of AD group were lower than those of control group [(7.92 +/- 2.22) microg/L, (259.74 +/- 41.92) microg/ d]. The incidence of hyperhomocysteinemia in AD group (64%) was higher than that in control group (22%). A significant relation between Hcy concentrations and the CDR was observed. With the increase of Hcy concentrations the CDR raised, and with the increase of Hcy concentrations the MMSE decreased.

CONCLUSIONHyperhomocysteinemia is one of the risk factors inducing the onset of AD. There is a significant negative correlation between Hcy levels and cognitive levels in AD group. Folate deficiency is an important reason to cause elevated Hcy levels in AD.