High blood pressure
When you have high blood pressure [2], the force with which your blood pushes against your arterial walls is much greater than the average person. This can weaken certain spots in the wall of your blood vessels or worsen already existing ones. Eventually, these weak spots may expand and fill with blood.
Brain aneurysms often look like a balloon attached to the blood vessels. Because these bulges are formed from very weak vessel walls, they can be ruptured easily. You should avoid activities or situations that can cause a sudden spike in your blood pressure, especially if you are already hypertensive.