The symptoms of persistent and generalized intellectual decline that occurs in the conscious state of the patient, manifested by reduced memory, calculation, judgment, attention, abstract thinking ability, language function, emotional and behavioral disturbances, and loss of ability to live and work independently are called dementia. With the progress of medicine, the expected age of people is gradually increasing, the process of aging of society is accelerating, and the number of people with dementia is increasing. It has become a major social problem that affects people’s health. Statistics show that the prevalence of dementia in people over 65 years old is about 5%. Moreover, the prevalence of dementia increases 0.74 times for every 5 years of age increase. Alzheimer’s disease includes dementia (Alzheimer’s disease AD), vascular dementia (VD) and mixed dementia. The main manifestations of Alzheimer’s disease are: 1. memory loss, which affects daily living activities; 2. difficulty in handling familiar things; 3. difficulty in expressing oneself verbally; 4. confusion about time, place and people; 5. diminishing judgment; 6. decreased comprehension or ability to arrange things rationally; 7. often putting things in inappropriate places; 8. emotional instability and behavior 9.Change in personality; 10.Loss of initiative. When the above symptoms are detected, the elderly should be sent to the hospital for neuropsychological tests and brain imaging examinations in a timely manner, and the correct diagnosis and treatment can be made by combining the patient’s medical history. If the patient can receive timely and correct treatment, it is possible to stop the rapid progression of the disease, prolong the time to develop heavy dementia and improve the quality of life of the patient. A simple method of the clock drawing test can help doctors diagnose Alzheimer’s disease. The method involves asking the patient to independently draw a clock on white paper with a specified time (e.g., 8:25, 9:10, etc.) and asking the elderly person being tested to complete it within ten minutes. There are various scoring methods for the clock drawing test, and the four-point method is now commonly used internationally: 1 point if the patient can draw a closed circle (dial); 1 point if the patient can place the numbers in the correct position on the dial; 1 point if the 12 numbers on the dial are correct; and 1 point if the patient can place the hands in the correct position. The maximum score is 4. A score of 4 indicates a normal level of cognition, a score of 3 indicates a mild decline in cognition, and a score of 0 to 2 indicates a significant decline in cognition. Studies have shown that the sensitivity of the clock drawing test in diagnosing early Alzheimer’s disease is between 80% and 90%. The clock test may seem simple on the surface, but many cognitive processes are involved in its completion. The cultural relevance of the clock test is very small. No matter what the language or level of education, as long as one can understand the simple prompts, one can draw a clock as required. It is easily accepted by patients and mastered by physicians. If an older person with normal intelligence becomes unable to draw a complete clock, his cognitive level must have declined.