Potential new risk factors for ischemic stroke: what is their potential?

BACKGROUND AND PURPOSE: About 60% to 80% of all ischemic strokes can be attributed to increasing blood pressure, blood cholesterol, cigarette smoking, carotid stenosis, and diabetes mellitus (atherosclerotic ischemic stroke), and atrial fibrillation and valvular heart disease (cardiogenic ischemic stroke). The aim of this review was to examine the potential role of other risk factors in the etiology of ischemic stroke. SUMMARY OF REVIEW: About 10% to 20% of atherosclerotic ischemic strokes can probably be attributed to recently established, causal risk factors for ischemic heart disease: raised apoB/apoA 1 ratio, obesity, physical inactivity, pyschosocial stress and low fruit and vegetable intake. However, their causal role remains to be proven. The direct genetic contribution of any single gene towards ischemic stroke is likely to be modest and apply in selected patients only and in combination with environmental factors or via other epistatic (gene-gene or gene-environmental) effects. CONCLUSIONS: Research resources should not be allocated disproportionately to emerging novel risk factors that may account for up to only 20% of all strokes at the expense of researching the determinants of the relatively few established causal factors that account for up to 80% of all strokes.