Fasting and Post-methionine Homocysteine Levels in Alzheimer's Disease and Vascular Dementia

The aim of the study is to compare the basal homocysteine levels in patients with impairment of cognitive status, and in controls, to evaluate if the methionine loading test is able to identify any differences between patients with Alzheimer's disease and patients with vascular dementia. We enrolled 56 subjects, 20 with Alzheimer's disease, 18 with vascular dementia, and 18 normal controls. The data shown that plasma homocysteine levels both basal and post-methionine load were significantly higher in the two groups of demented patients than in the control group. No significant differences were found between Alzheimer's patients and vascular dementia patients. The homocysteine percent increase after a methionine loading test was significantly higher in the controls with respect to the two groups of demented patients. Only in Alzheimer's patients were vitamin B-12 basal levels negatively correlated with basal homocysteine levels (p<0.05), while positively correlated with the homocysteine percent increase after load (p<0.05). The study confirms the possible role of chronically elevated homocysteinemia in neuronal degeneration in demented patients. Even if the methionine loading test revealed an abnormal homocysteine metabolism in demented patients, it didn't show any difference among patients with Alzheimer's disease and vascular dementia.