Strokes? Hypertension , if it is high enough can cause a bleed into the brain ( a hemmorhagic stroke) and if is untreated for years can cause hardening of the arteries which can lead to an ischemic stroke.
Atherosclerosis. Chronic hypertension contributes to the development of plaque within the arteries. The plaque can then rupture and lead to a stroke either in place if the plaque is within the brain arteries, or by embolization from the aorta, or carotid arteries in the neck. A very high blood pressure occurring acutely can cause a hemorrhagic stroke by rupturing a small vessel within the brain.