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(Stroke. 2003;34:833.)
© 2003 American Heart Association, Inc.

Letters to the Editor

Immune Activation to Underlie Moderate Hyperhomocysteinemia in Stroke and Dementia?

Institute of Medical Chemistry and Biochemistry, University of Innsbruck, Innsbruck, Austria

An extract of the first 250 words of the full text is provided, because this article has no abstract.

To the Editor:

With interest we read the article by McIlroy et al,¹ in which moderate hyperhomocysteinemia was described in patients with vascular dementia, stroke, and Alzheimer’s disease (AD) in comparison with control groups. The authors suggest that mild hyperhomocysteinemia may significantly increase the risk for vascular dementia, AD, or stroke. Korczyn² argues against this conclusion, suggesting other causes like endothelial dysfunction in consequence of oxidative stress to be important as contributing factors for dementia. Likewise, hyperhomocysteinemia could be a consequence of stroke and dementia rather than its cause.

In earlier studies in patients with AD, deficiency of B-vitamins folate and vitamin B₁₂ was associated with elevated plasma homocysteine concentrations.^3–5 Thus, diminished availability of essential cofactors in the homocysteine-methionine-metabolism appears to be responsible for elevated homocysteine concentrations. Usually insufficient dietary intake is considered as the cause for the deficiency of these vitamins,^3–5 and folate deficiency can cause several neurologic and psychiatric symptoms, especially in the elderly.⁶

There seems to exist a link between oxidative stress involved in the pathogenesis of dementia and stroke and the depletion of B-vitamins. Since activation of immunocompetent cells like T-lymphocytes and macrophages is associated with overwhelming production of oxidizing compounds, immune activation is a major cause of oxidative stress.⁷ Oxidative stress in scope with chronic immune activation could therefore lead to the depletion of antioxidants including oxidation-sensitive vitamins like folate and vitamin B₁₂. Methyl-tetrahydrofolate and cobalamine are important cofactors in the biochemical conversion of homocysteine and both are readily oxidized.^7,8 Chronic immune activation has . . . [Full Text of this Article]

Stephen P. McIlroy, PhD A. Peter Passmore, MD

Department of Geriatric Medicine, Queen’s University of Belfast, Belfast, Northern Ireland