How long does it usually take for a brain aneurysm to develop?

Unknown: Aneurysms can be congenital (born with them) but are more commonly acquired (i.E develop as we age). They are associated with untreated hypertension, high cholesterol, smoking, diabetes, and even drug abuse. Aneurysms have been known to develop in as quickly as 1-2 years, but more likely grow slowly over a decade or two.

No on knows: The most common type of brain aneurysm is called saccular and it is unclear how long they take to develop. Another, less commin, type are called mycotic aneurysms. They are due to infections can develop in days to weeks.