Unruptured cerebral aneurysms (UCAs) have an overall seven percent prevalence in Chinese adults ages 35 to 75, according to a study published on Oct. 15 in the Annals of Internal Medicine.

A cross-sectional study conducted from June 2007-2011 by Ming-Hua Li, MD, of Shanghai’s Institute of Diagnostic and Interventional Radiology, and colleagues measured the prevalence of UCAs by using three-dimensional time of flight magnetic resonance angiography (3D-TOF MRA) in 4,813 adults from two randomly selected urban and suburban communities from two districts in Shanghai.

Participants were asked to fill out a questionnaire with basic demographic information and underwent a physical health screening prior to 3D-TOF MRA. Once all study participants were screened, three blinded radiologists interpreted the collected data to identify location and size of the UCAs, as well as estimate their overall age and sex-specific prevalence.

Results indicated that 369 UCAs were discovered in 336 people, 130 of whom were men and 230 who were women. 4,077 participants did not have any UCAs. The overall prevalence of UCAs in this population was seven percent. Eighty-one percent of the aneurysms were found in the internal carotid artery, and 90.2 percent had a maximum diameter of less than five millimeters. UCAs peaked at ages 55 to 64 in both sexes, though they were found more commonly in women.

“We noted that the prevalence of UCAs was higher in women than in men, and the mean maximum aneurysm diameter was also larger in women,” wrote Li and colleagues. “Therefore, our finding is in line with the hypothesis that decreases in estrogen concentration and estrogen-receptor density may contribute to an increased risk for cerebral aneurysms in women.”