The relation between homocysteine levels and development of Alzheimer's disease in mild cognitive impairment patients.

The aim of this study was to investigate over a 3-year period the connection between homocysteine (Hcy) levels and development of Alzheimer's disease (AD) in patients with mild cognitive impairment (MCI). Hcy was analyzed in 68 men, mean age 65 years, and 68 women, mean age 64 years. Age, sex, cobalamin, folate, creatinine, and thyroid profiles as well as results of Mini-Mental State Examination at the first visit to the memory investigation unit of a geriatric department were recorded from patient journals collected between 1992 and 1999. The total numbers of persons who converted to AD within a period of 3 years from initial investigation with baseline Hcy sampling was 12 of 46 (26%) males, and 18 of 50 women (36%). The total percentage of men and women converting to AD was 31%. Thirty-three percent of men with Hcy levels >20 micromol/l converted to AD. The corresponding figure for men with Hcy levels 20-17 micromol/l was 50%, whereas none of the 18 men with Hcy levels <17 micromol/l converted to AD. These differences were statistically significant. There was also a statistically significant difference between the percentage of women with Hcy levels >16 micromol/l who converted to AD (45%) as compared to those with Hcy levels <16 micromol/l who converted (21%). These findings are inconsistent with the results of other studies showing a positive correlation with hyperhomocysteinemia and occurrence of AD. However, our findings tentatively suggest a possible protective effect of low/normal Hcy levels on dementia conversion in MCI patients.