At present, there are 120 million people over 60 years old in China. Domestic and international studies suggest that the incidence of dementia in the elderly will gradually increase with age, and the prevalence of dementia in the elderly over the age of 80 can reach more than 30%. 1. Memory impairment: Memory impairment in Alzheimer’s disease is characterized by impaired ability to remember new knowledge and difficulty in recalling distant knowledge. Memory impairment appears in the early stage, firstly, the near memory is impaired, and then the distant memory is also impaired. The daily performance of the patient is “losing three things”, “forgetting after finishing” and repeatedly asking the same questions. However, when the patient’s early amnesia has become apparent, the distant memory is relatively preserved, so that relatives often believe that the patient’s memory is not poor. The reason is that things that happened decades ago are clearly remembered, so it is easy to ignore. Memory loss is also a core symptom of early cerebrovascular dementia. 2. Visual-spatial skill impairment: inability to accurately determine the location of objects; knocking objects over when reaching for them. Getting lost in a familiar environment. By the middle stage, disorientation also occurs at home and cannot find one’s room. There are obvious difficulties in dressing in daily life, unable to judge up and down and left and right, such as wearing the chicken heart collar backwards, wearing the pants backwards, etc. 3. Language impairment: Early on, there is difficulty in finding words, but the naming of items may be normal, and impaired listing is a sensitive indicator of early Alzheimer’s disease. With the development of the disease, the name of commonly used items and the name of relatives also appear to be unable to name, while the wrong language. Family members often call it “ talk east and west ”, while listening to understand serious impairment, often answer is not the question, the ability to talk down, and finally to silence. 4, writing difficulties: often appear in the early stage. The content of the written word does not reach the meaning, there are a lot of misspellings (the strokes look like Chinese characters, but the strokes are wrong, or even non-existent new words). By the middle and late stages of the disease, one does not recognize and cannot write one’s name. 5. Loss of use and recognition: About 1/3 of patients have visual loss of recognition. They do not recognize the faces of their relatives and familiar friends. Loss of use is common in the middle stage, i.e., after memory and language impairment has become apparent and before motor inability becomes apparent. Inability to make continuous complex movements correctly with hand gestures, such as filling a pipe, striking a match, or lighting a cigarette. Inability to perform spontaneous movements on command, e.g., the patient can brush teeth with a toothbrush but cannot do so on command. Loss of skills that have been mastered, such as bicycling and swimming, but not after the disease, and in severe cases, even can not hold chopsticks or eat with a spoon. 6. Arithmetic disorder: It may be manifested at an early stage, such as not being able to calculate or miscalculate accounts for shopping. Even do not recognize numbers and arithmetic symbols, and can not answer the examiner how many fingers are extended. 7. Poor judgment and distraction: Poor judgment, distraction, loss of recognition and lack of concentration may appear in the early stage, and work is often erroneous. However, the decline of intelligence in vascular dementia is not comprehensive. Lesions located in the cortex of the left cerebral hemisphere may have symptoms of aphasia, loss of use, loss of reading, loss of books, loss of arithmetic, etc.; lesions located in the cortex of the right cerebral hemisphere may have visual-spatial perception disorders; lesions located in the subcortex may have corresponding motor, sensory and extrapyramidal disorders, and may also have symptoms of strong laughing and crying, and sometimes mental symptoms such as hallucinations, self-talk, xylophobia, reticence, apathy, etc. 8, mental functional psychiatric disorders: emotional indifference often appears early, showing mania, hallucinatory delusions, depression, personality and behavior changes, delirium, etc. Do not like to interact with people, lack of affection for loved ones; bad temper, suspicious, selfish, regardless of major issues, chicken and garlic things with you endlessly; the sleep does not sleep, senior emotional activities (sense of shame, honor, responsibility, morality, etc.) have different degrees of decrement. 9, movement disorders: early often normal performance, to the middle of the performance of excessive activity of restlessness. Such as walking back and forth indoors without purpose, or getting up in the middle of the night, touching everywhere, opening and closing doors, carrying things, etc. This is followed by loss of instinctive activity, incontinence (urination is not easily controlled and may appear earlier), and inability to take care of oneself. Motor disorders appear only in the late stage, and finally tonic or flexion tetraplegia appears. There is a general decline in intelligence and no conscious response to external stimuli, manifesting as immobility and silence. The diagnosis requires physical examination, especially advanced neurological examination, often combined with dementia scale measurement, necessary laboratory tests such as EEG, cranial CT and MRI, cerebral blood flow measurement and blood biochemical tests to further strengthen the clinical diagnosis and differential diagnosis. In order to treat dementia early, correctly and actively, especially those with treatable dementia.