Plasma total homocysteine and memory in the elderly: The Hordaland Homocysteine study

We examined the relation between plasma total homocysteine (tHcy), folate, vitamin B12, and episodic memory in elderly community‐dwelling subjects. A population‐based study was conducted in 1992 and 1993, and subjects were re‐investigated after 6 years. Plasma analytes were determined on both occasions. At follow‐up, memory performance, using the Kendrick Object Learning Test, was investigated in 2,189 subjects (age, 65–67 years at baseline). Subjects with memory deficit (test score, <25) had higher tHcy and lower folate at follow‐up compared with those without memory deficit: 12.6 (95% confidence interval [CI], 12.1, 13.1) versus 11.5 (95% CI, 11.3, 11.6) μmol/L (p < 0.001) for tHcy, and 6.7 (95% CI, 6.2, 7.1) versus 7.6 (95% CI, 7.5, 7.8) nmol/L (p < 0.001) for folate. The risk of memory deficit increased according to quintiles of tHcy both at baseline and at follow‐up. A decline in tHcy, or an increase in folate, over a 6‐year period was associated with a higher memory test score; and vice versa. These findings indicate that increased plasma tHcy is an independent risk factor for memory deficit both cross‐sectionally and prospectively, and that a “favorable” change in folate or tHcy concentrations over time is associated with better memory performance. Ann Neurol 2005