alzheimer's disease (ad) is a brain disease that slowly destroys brain cells. as of now, there is no cure for alzheimer's disease. with time, the different symptoms of the disease become more marked. many people die because of alzheimer's disease. the disease affects different parts of the brain but has its worst effects on the areas of the brain that control memory, language, and thinking skills. alzheimer's disease is the most common form of senile dementia accounting for up to 70% of cases.