Brain aneurysms are caused by a weakness in the walls of blood vessels in the brain. This weakness can be due to inherited factors, damage over time, or other contributing factors. Common causes and risk factors include:
- Cigarette smoking and high blood pressure, which can damage and weaken artery walls.
- Genetic predisposition or family history of brain aneurysms.
- Age (more common in adults over 40) and female gender.
- Other medical conditions such as connective tissue disorders (e.g., Ehlers-Danlos syndrome, Marfan syndrome), polycystic kidney disease, coarctation of the aorta, and brain arteriovenous malformations.
- Use of drugs like cocaine and amphetamines, excessive alcohol use.
- Severe head trauma or infections affecting blood vessel walls.
Aneurysms often develop at branching points in blood vessels where vessel walls tend to be weaker. They enlarge due to blood pressure stressing these weak spots, which can eventually cause the vessel wall to balloon out or rupture.