Relation between plasma homocysteine and Alzheimer's disease.
OBJECTIVE
Several studies have shown that plasma total homocysteine (tHcy) concentration is elevated in Alzheimer's disease (AD). However, it is not clear whether elevated plasma tHcy is a primary cause or a consequence of AD.


METHODS
To elucidate this question, we have analysed plasma homocysteine and its determinants in patients with early (EOAD)- and late-onset AD (LOAD) and compared the findings with those in vascular dementia (VaD) and age- and sex-matched control subjects.


RESULTS
One of the main findings in the present study is that in EOAD there is no change in the levels of either plasma tHcy or its determinants compared with an age- and sex-matched control group. The fact that plasma tHcy concentration is normal in EOAD thus indicates that elevated plasma tHcy is not the primary cause of the disease. Another main finding is that patients with mixed dementia (AD and VaD) and patients with VaD showed significantly increased plasma tHcy concentration compared with controls and that plasma tHCy concentration in patients with LOAD and a history of additional cardiovascular disease was elevated compared both with AD patients without such a history and with the controls. Thus, there is an association between elevated plasma tHcy and vascular disease. A third main finding is that patients with AD who were followed up for several years showed a clinical deterioration of dementia and an elevation of plasma tHcy concentration. This finding likewise supports the notion that elevated plasma tHcy is not the primary cause of the disease.


CONCLUSIONS
The findings suggest that elevated plasma tHcy is not the primary cause of the disease. Furthermore, the findings indicate that elevated plasma tHcy might be a reflection of concomitant vascular disease in AD patients.
Nilsson
Karin
K
Department of Psychogeriatrics, Division of Clinical Chemistry, University Hospital, Lund, Sweden.
Gustafson
Lars
L
Hultberg
Björn
B
D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000097:blood*; D005260:Female; D006710:Homocysteine / Q000097:blood*; D006801:Humans; D008297:Male; D016555:Matched-Pair Analysis; D014652:Vascular Diseases / Q000097:blood
D006710:Homocysteine