The cause of Alzheimer's disease is misunderstood. The cause of Alzheimer’s is believed to be about 70% genetically related. A history of head injuries, depression or hypertension can also increase the risk of developing Alzheimer’s. It most often begins in people over 65 years of age.Affected people increasingly rely on others for assistance as the disease progresses, often placing a burden on the caregiver; the pressures can include social, psychological, physical, and economic elements.Examination of brain tissue is needed for a definite diagnosis. In some cases the initial symptoms are often mistaken for normal ageing. There is no medication or treatment to prevent the disease, only treatments can temporarily improve the symptoms. Mental and physical exercise and also avoiding weight gain may decrease the risk of AD. Exercise programs can potentially improve outcomes and improve their daily living abilities.