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Homocysteine and risk of stroke
1Department of Epidemiology & Public Health, University College Cork, Republic of Ireland. i.perry@ucc.ie
Insights
Elevated homocysteine levels may increase stroke and carotid artery disease risk. More prospective studies and trials are needed to confirm causality and guide public health strategies for hyperhomocysteinaemia.
Area of Science:
- Cardiovascular Epidemiology
- Metabolic Disorders
- Neuroscience
Background:
- Observational studies suggest a link between high homocysteine and increased risk of carotid artery disease and stroke.
- Concerns exist regarding confounding factors like renal impairment, diet, and smoking in hyperhomocysteinaemia.
- Genetic factors, such as MTHFR polymorphism, have not been consistently associated with stroke risk.
Purpose of the Study:
- To evaluate the association between homocysteine levels and stroke risk.
- To investigate the nature of this association (linear vs. threshold).
- To explore interactions between homocysteine, dietary markers, and established stroke risk factors.
Main Methods:
- Analysis of observational study data.
- Identification of a need for prospective studies with adequate statistical power.
- Emphasis on the requirement for randomized controlled trials (RCTs) of homocysteine-lowering interventions.
Main Results:
- Existing evidence is largely from observational studies, with limited prospective data.
- The genetic link via MTHFR polymorphism is inconsistent.
- Homocysteine levels tend to rise with age and are prevalent even in well-nourished populations.
Conclusions:
- Further prospective studies are essential to clarify the homocysteine-stroke relationship.
- Randomized controlled trials are crucial to establish a causal link between elevated homocysteine and vascular disease.
- Even modest effects of homocysteine on stroke risk have significant public health implications due to its prevalence.
Abstract:
The balance of evidence from observational studies suggests that elevated levels of homocysteine are associated with increased risk of carotid artery disease and stroke. There is, however, a paucity of prospective studies. There are also concerns regarding confounding caused by factors associated with hyperhomocysteinaemia, including renal impairment, an atherogenic diet and cigarette smoking. Homozygosity for a defective thermolabile variant of methylene-tetrahydrofolate reductase, a common genetic polymorphism which results in hyperhomocysteinaemia, has not been consistently linked with stroke or other vascular diseases. Additional prospective studies are required, with sufficient power to characterise the form of the association between homocysteine concentrations and stroke risk, whether linear or threshold, and to study interactions between homocysteine, other dietary markers and established stroke risk factors such as smoking and hypertension. Ultimately, the case for a causal role for elevated levels of homocysteine in vascular disease, including stroke, will depend on data from randomised controlled trials of homocysteine-lowering interventions. Given the high prevalence of hyperhomocysteinaemia in apparently well-nourished populations and the tendency for homocysteine concentrations to increase with age, modest effects of homocysteine on stroke risk will have profound implications for public health.