Alzheimer’s disease is a serious intellectual disability that takes patients from mild memory and cognitive impairment to a final vegetative state over several years or even decades, which is a painful process for both the patient and the family. Alzheimer’s disease is like an “epidemic” with a rapid increase in incidence among the elderly. The majority of patients do not seek treatment in a timely manner or do not go to the hospital at all, and their quality of life is low, which should be a concern for society and families. With the increasing per capita life expectancy, it is expected that by 2015, one of the four people over the age of 80 supported by a couple may be an Alzheimer’s patient. Dementia syndromes can be divided into cortical dementia, subcortical dementia, mixed cortical and subcortical dementia, and other dementia syndromes according to the site of the lesion. Cortical dementia can be divided into Alzheimer’s disease and prefrontal degenerative lesions; subcortical dementia has more types, such as extrapyramidal syndrome, hydrocephalus, white matter lesions, cerebrovascular dementia; mixed cortical and subcortical dementia can be divided into multi-infarct dementia, infectious dementia, toxic and metabolic encephalopathy; other dementia syndromes such as post-traumatic brain injury, subdural hematoma, etc. Is it necessarily Alzheimer’s disease when elderly people have symptoms such as memory loss, unfavorable leg and foot movement, unstable walking and incontinence? The answer is no. According to Japan’s 2011 guidelines, 1/6 of the total number of people with Alzheimer’s disease belong to hydrocephalus dementia, the medical name of which is “normal cranial pressure hydrocephalus dementia”, which is easily overlooked because the symptoms are very similar to those of Alzheimer’s disease. This disease is a special type of hydrocephalus with normal intracranial pressure, also known as occult hydrocephalus, the onset of which is very insidious, but the important point is: it is curable! Normal cranial pressure hydrocephalus dementia is a state of chronic hydrocephalus in which the cerebral ventricles are enlarged but the cerebrospinal fluid pressure is normal. It is common in 60-80 year olds, and the prevalence in Japan is 0.5% in people over 61 years old and 2.9% in people over 65 years old. The disease usually starts slowly and progresses gradually. Memory loss, poor mood, indifference, and in severe cases, apparent dementia (can be mistaken for common dementia); abnormal walking gait, small stride, unstable walking, and inability to lift the feet (often misdiagnosed as Parkinson’s disease or cerebrovascular disease, etc.); increased urination, a sense of urgency, and in severe cases, urinary incontinence (often seen in urology). Hydrocephalus dementia can usually be treated surgically. The most commonly performed clinical procedure is ventriculo-abdominal shunt, in which water in the brain is drawn out through a tube by implanting an adjustable pressure shunt in the brain, thus relieving hydrocephalus and improving or relieving symptoms. Many people tend to mistake hydrocephalus for Alzheimer’s disease. Normal pressure hydrocephalus may be present in the elderly and its cause may be related to altered cerebrospinal fluid circulation in the arachnoid pool at the base of the brain. Normal pressure hydrocephalus is a slowly developing hydrocephalus that is caused by dilatation of the ventricular system due to a mild pressure gradient between the ventricles and brain tissue. It occurs most often in older adults over the age of 60 and is slightly more common in men. ”Hydrocephalus is a relatively common disease in the elderly, showing three symptoms depending on the degree of the disease: 1) memory loss; 2) unstable walking; 3) slight tremors in the hands and feet, and a bit of control in relieving urine. Those with mild disease only show memory loss.” Because Alzheimer’s and hydrocephalus show similar symptoms, many people are easily confused. Alzheimer’s disease is a degenerative disease of the central nervous system that is dominated by progressive cognitive impairment and memory damage. The elderly should not simply assume that Alzheimer’s disease is the cause when they have symptoms such as memory loss, motor impairment and incontinence, but should go to a major hospital for relevant examinations in time to avoid delays.