About the Study: In this population-based cohort study of 544 survivors of aneurysmal subarachnoid hemorrhage younger than 40 years, 19.5% developed a radiologically detected de novo intracranial aneurysm during follow-up, and the 40-year cumulative incidence was 30.2%. Female sex, smoking, and family history were independently associated with de novo aneurysm formation. Smoking cessation was associated with lower risk, and no ruptures were observed under systematic surveillance. The findings indicate that young survivors of aneurysmal subarachnoid hemorrhage have a persistent long-term risk of radiologically detected de novo intracranial aneurysm formation that continues to rise over decades rather than plateauing over 40 years of follow-up estimates. They also indicate that female sex, smoking, and family history of intracranial aneurysm were independent risk factors, and that smoking cessation was associated with lower risk. The study further found that no de novo ruptures occurred under systematic surveillance, and the authors conclude that these results support lifelong, risk-stratified radiological surveillance and smoking cessation counseling.
Corresponding Author: Peter Alpkvist, MD, Department of Neurosurgery, Karolinska University Hospital, 171 76 Stockholm, Sweden ( peter.alpkvist@regionstockholm.se ).
10.1001/jamaneurol.2026.2830
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JAMA Neurology