Pre-existing symptoms of Alzheimer’s disease mainly include memory loss, decreased learning ability, disorientation, mood disorders, and decreased language function. 1. Memory loss: Memory loss is the earliest symptom of patients, and it is mainly manifested in the early stage of near memory loss, with the progress of the disease, far memory loss can occur. 2. Decreased learning ability: the patient’s ability to learn new things is obviously reduced, and it is more difficult to learn, and may need to learn again and again in order to master. 3. Orientation disorder: patients will have a decreased sense of direction, mainly manifested as patients will get lost in familiar places, such as patients in their own home neighborhood, but also appear to be unable to find their way home. 4. Mood disorders: mood disorders are mainly manifested by patients’ low mood, depression, and their inability to show much interest in things they used to be interested in. 5. Decreased language function: Decreased language ability is mainly manifested by the patient’s difficulty in speaking, often unable to accurately express their own meaning. If the elderly appear the above symptoms, suggest that may be dementia, need to go to the regular hospital in a timely manner, under the guidance of the physician to improve the relevant cognitive examination, a clear diagnosis and give targeted treatment.