Intracranial atherosclerosis may be a risk factor for stroke in whites and may play a role in a greater number of strokes than large-artery atherosclerosis in other vessel beds, according to a study published online Feb. 17 in JAMA Neurology.

There have been few studies evaluating the role of intracranial atherosclerosis in whites. “Thus far, evidence of a role of intracranial atherosclerosis in the etiology of stroke comes primarily from research in populations of Asian and African descent,” explained the authors, led by Daniel Bos, MD, PhD, of Erasmus Medical Center in Rotterdam, the Netherlands.

They examined a cohort of mostly white participants from the previously conducted Rotterdam Study, a trial that looked at factors involved in chronic diseases in the elderly. Bos and colleagues performed CT scans on 2,323 randomly selected Rotterdam Study participants between 2003 and 2006 and quantified intracranial carotid artery calcification (ICAC). They monitored the participants for incident stroke until Jan. 1, 2012.

There were 91 incident strokes, and 74 of them were ischemic. A greater volume of ICAC was associated with a higher stroke risk, (the hazard ratio was 1.43 for every increase of one standard deviation in ICAC volume) regardless of the presence of cardiovascular risk factors, ultrasound carotid plaque score and calcification in other vessels.

Intracranial atherosclerosis was a factor in 75 percent of all strokes, a much higher percentage than atherosclerosis in the aortic arch (45 percent) and extracranial carotid artery (25 percent).

Although the emphasis has been on coronary artery atherosclerosis as a risk factor for cardiovascular events, the authors argued that their findings suggest ICAC should be a research focus. Their study did not find an association between coronary artery calcification and stroke when considering calcification in all vessel beds. In a post hoc analysis, they found coronary artery calcification associated with stroke in a crude age and sex-based model.

“Future studies should thus investigate the predictive value of ICAC for stroke,” they wrote.