Decreased ability to perform activities of daily living and behavioral abnormalities are a typical manifestation of Alzheimer’s disease. Alzheimer’s disease (AD) is the most common form of dementia. Alzheimer’s disease is a primary degenerative encephalopathy that occurs in old age and pre-mature old age. It is a persistent impairment of higher neurological functions, i.e., memory, thinking, analysis and judgment, visual-spatial recognition, and emotion, without impairment of consciousness. So, what are the causes of diminished daily living abilities and behavioral abnormalities in the elderly? Patients with Alzheimer’s disease experience extensive brain cell death, especially in the basal ganglia region. Normally, fibers emanating from the basal ganglia area project to the brain’s memory- and cognition-related cortex, which releases acetylcholine. Acetylcholine must be involved in the formation of short-term memory, and patients have 90% less acetylcholinesterase compared to normal subjects. The patient’s brain was found by autopsy to have extensive neuronal fiber tangles and axonal tangles forming senile plaques. The senile plaques contained fragments of necrotic neuronal cells, aluminum, abnormal proteins, and excessive accumulation of beta-amyloid in the brains of Alzheimer’s disease patients. It is also associated with the gene for apolipoprotein E (APO-E4), an increase in which counteracts the function of APO-E2 or APO-E3. APO-E4 decreases the stability of neuronal cell membranes, leading to neuronal fiber tangles and cell death. pure congeners of the APO-gene are more likely to have the disease than heterozygotes.