Homocysteine and stroke: another brick in the wall

After a long debate, due to conflicting data from clinical studies, homocysteine is now largely accepted as a risk factor for cardiovascular diseases including stroke. To date, the role of elevated homocysteine levels in stroke recurrences has not been evaluated. In the present issue of Clinical Science, Zhang and co-workers prove that Chinese patients with high homocysteine levels have an increased risk of stroke recurrence and of all-cause mortality with respect to patients with lower levels. Remarkably, in their study, high homocysteine levels were associated with an increased risk of stroke recurrence for atherothrombotic stroke and intracerebral haemorrhage, but not lacunar stroke. The study by Zhang and co-workers provides important information for clinical practice and represents the basis for further investigations, as it raises questions referring to the puzzling relationship between homocysteine and cardiovascular disease. Moreover, the results support the hypothesis that, for undisclosed reasons, the relationship between homocysteine and cardiovascular disease may not be homogeneous for all the conditions encompassed in the category of cardiovascular disease, being peculiar for stroke patients. The finding of an association between high homocysteine levels and a risk of recurrent stroke or all-cause mortality in patients with intracerebral haemorrhage should be taken with caution until this same result is confirmed in other case series with different ethnicity.