High or uncontrolled blood pressure can cause your blood vessels to rupture, leak or become narrow. It can also lead to the formation of blood clots in your brain, thereby restricting the blood flow and causing a stroke. The patient can sometimes also have a mini-stroke (Transient Ischemic Attack- TIA) that restricts the blood supply to the brain. This attack is often a warning that you are at a risk of a getting a serious stroke