- The prevalence of unruptured brain aneurysm rose from 2.9% to 6.6% over two decades, a systematic review and meta-analysis showed.
- The higher prevalence appeared partly independent of the aging population and improved imaging, suggesting that unknown risk factors may play a role.
- Researchers supported targeted screening for high-risk groups, not broad screening of healthy adults.
Unruptured brain aneurysms were identified more frequently in recent years, a systematic review and meta-analysis showed.
In studies of healthy people who had MR or CT angiography, the prevalence of an unruptured intracranial aneurysm rose from 2.9% to 6.6% over two decades, reported Nima Etminan, MD, of the University of Heidelberg in Mannheim, Germany, and co-authors.
After adjusting for age and sex, the prevalence ratio was 1.8 (95% CI 1.1-2.8) for 2016-2022 compared with 2002-2015.
The increase in unruptured aneurysms “is only in part explained by aging of the population and improvements in vascular imaging, which suggests that other, as yet unknown (e.g., environmental), risk factors play a role as well,” Etminan and colleagues wrote in Lancet Neurology.
Aneurysms were more common in women, older people, and those who smoked or had hypertension, the researchers said. People with connective-tissue disorders, a positive family history of aneurysmal subarachnoid hemorrhage, or autosomal dominant polycystic kidney disease also had a higher prevalence.
Unruptured brain aneurysms are often incidental findings on MR or CT angiography. They gained national attention last year when reality television star Kim Kardashian said she was diagnosed with one. Most are asymptomatic, but some rupture and cause aneurysmal subarachnoid hemorrhage, which can lead to early death or long-lasting impairments.
The overall incidence of aneurysmal subarachnoid hemorrhage has declined by 40% in the past three decades, in parallel with declines in smoking and hypertension. Despite this, “the proportion of people with an unruptured intracranial aneurysm — now about one in 15 healthy adults — is increasing,” Etminan and co-authors observed.
An incidental diagnosis of an unruptured brain aneurysm has clinical implications, noted Shuo Wang, MD, of Capital Medical University in Beijing, and co-authors in an accompanying editorial.
“Prophylactic surgical or endovascular intervention can involve procedural risks, and surgical complications cause net clinical harm for lesions with low risk of rupture,” they pointed out.
“With high-resolution imaging and AI [artificial intelligence]-assisted screening expanding rapidly, more unruptured intracranial aneurysms will be identified in future clinical practice,” the editorialists predicted.
This study “validates hypertension and smoking as established risk factors and identifies individuals with connective-tissue disorders as a novel high-risk subgroup, complementing well characterized high-risk subgroups such as patients with autosomal dominant polycystic kidney disease and people with a positive family history of aneurysmal subarachnoid hemorrhage,” Wang and colleagues noted.
“Taken together, these findings support targeted screening of people at substantially increased risk of harboring an unruptured intracranial aneurysm, rather than non-selective screening of the general population,” they wrote.
The systematic review and meta-analysis included 162 studies and data for 316,131 people and 11,822 patients with unruptured intracranial aneurysms published between September 1955 and July 2025. About half of the studies (51%) were considered high quality, 36% moderate quality, and 12% poor quality.
Overall, the estimated prevalence of an unruptured intracranial aneurysm was 3.9%. The prevalence for people with atherosclerosis was 5.5%; for those with a positive family history of aneurysmal subarachnoid hemorrhage or unruptured intracranial aneurysms, it was 7.9%. For people with connective-tissue disorders, the prevalence was 10.3%, and for those with autosomal dominant polycystic kidney disease, it was 12.8%.
Risk ratios were 1.4 for current smoking, 1.6 for hypertension, and 1.9 for female sex.
“Our findings warrant further investigation into the potential benefit of personalized screening and management strategies in groups at high risk for having unruptured intracranial aneurysms,” Etminan and colleagues wrote.
The meta-analysis was derived mostly from selected cohorts and cross-sectional studies, rather than unselected population-based studies, the researchers acknowledged. “Nonetheless, our data on population-based studies underscore that the prevalence in such populations does not differ substantially from prevalence data in more selected cohorts of healthy individuals,” they noted.
“The higher prevalences in patients with connective-tissue disorders cannot be generalized to every connective-tissue disorder, as we pooled these studies because of the scarcity of the data,” they added.
