A new study from UC San Francisco shows how certain cells in the brain may cause aneurysms to weaken and rupture. It helps explain why some aneurysms burst while others do not and could lead to new ways of predicting and possibly preventing strokes.

Brain aneurysms are bulges in blood vessels that can go unnoticed for years. If they rupture, they can cause a severe and often deadly type of stroke. About one in 50 Americans has a brain aneurysm, but doctors still struggle to predict which ones are most dangerous.

The new study helps to unpack the biology behind these events by mapping the cells in artery walls and the interactions that weaken them.