Alzheimer’s disease in the elderly not only destroys the otherwise beautiful life situation, but is also a huge burden on the family economy. So what are the causes of Alzheimer’s disease? 1. Genetic factors: Many studies at home and abroad have proved that the offspring of Alzheimer’s patients have more chances to suffer from this disease. However, the mode of inheritance is still unclear. Some people believe that it is a dominant gene inheritance, others believe that it is a recessive gene inheritance, and others believe that it is a polygenic autosomal recessive inheritance, and the genetic effect can be subject to environmental factors and mutations of genetic factors, so as to interrupt its genetic effect. There are also some studies that consider Alzheimer’s as a non-genetic disease, such as vascular dementia with no direct relationship with heredity. Brain degenerative diseases: There are many kinds of dementia caused by brain degenerative diseases, the most common one is Alzheimer’s disease dementia, which is also called progeria if it develops in the early age. 3. Intracranial infection: It is a common cause of dementia. Intracranial infections lead to changes in brain parenchyma and brain function, resulting in dementia, such as various encephalitis, neurosyphilis, various meningitis, kuru disease, etc. 4.Nutritional and metabolic disorders: The brain tissue and its function are damaged due to nutritional and metabolic disorders, leading to dementia. 5.Other: Traumatic brain injury, persistent seizures of epilepsy, and normal pressure hydrocephalus can cause dementia. In addition, long-term emotional depression, isolation, widowhood, illiteracy, low language level, lack of physical and mental exercise in the elderly can also accelerate the process of brain aging and induce dementia.