DENVER, CO (American Academy of Neurology) -- Higher levels of testosterone are related to lower risk of stroke in men. This lower stroke risk was only seen in men who do not smoke, according to a study presented at the annual meeting of the American Academy of Neurology. Estrogen levels are not related to stroke risk in either men or women.

Sex hormones have long been hypothesized to play an important role in the discrepancy in cardiovascular disease occurrence between men and women. While some studies have suggested that hormone replacement therapy may decrease the risk of heart disease, the role of hormones we generate ourselves had not yet been investigated.

"We excluded participants who used hormone therapy in our study, which followed 6,732 persons over the course of five to eight years," said study author Monika Hollander, MD, of Erasmus Medical Center, Rotterdam, Netherlands. Hollander and fellow researchers then compared serum levels of testosterone and estrogen between 97 men and 120 women who experienced a stroke during the course of the study and persons who remained stroke-free. The investigators looked at the role of many traditional stroke risk factors such as smoking and high blood pressure as well as investigating whether there was an interrelationship between endogenous testosterone or estrogen and these risk factors.

The study suggests possible factors that may play a role in the etiology of stroke. The precise mechanism underlying the relationship between testosterone and stroke in men and the relationship between smoking and testosterone in stroke risk in men needs to be further studied. The study was sponsored by the Netherlands Organization for Scientific Research.