Research on A Risk Factor for Stroke

British researchers attempted to shed some light on an amino acid in the blood long suspected as a risk factor for stroke.

The study results suggest people who carry a gene that produces a higher level of the amino acid homocysteine have a small increased risk for stroke. If confirmed by other studies, the finding could lead to treatment with folic acid and vitamin B, which are known to reduce homocysteine levels in the blood.

The research involved a review of the medical literature on homocysteine levels and stroke. Most of the work so far, report the authors, has been observational in nature. Therefore, investigators question whether the link between stroke and homocysteine levels might be influenced by other factors also known to cause an increase in stroke risk, such as smoking and lower socioeconomic status.

The authors of this study used a standard scientific approach to weed out the confounding factors by looking at data on the link between homocysteine and gene variations that cause people to have higher or lower levels of the amino acid in their blood. They compared risks from observational studies with those from the gene-based studies to arrive at their findings.

Other researchers writing in a commentary in the same issue, however, say it’s too soon to say the gene variation causing higher homocysteine levels is really to blame for an increased risk of stroke in that population, noting the gene variation itself may also affect behavioral or socioeconomic factors that could be increasing the stroke risk.

Both the study authors and the commentators agree more study is needed before doctors should begin prescribing folic acid and/or vitamin B for people with higher homocysteine levels.

SOURCE: The Lancet, 2005;365:224-232,194-195

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