Decreased ability to perform daily living and behavioral abnormalities: a variety of higher cortical functions are disturbed, involving memory, thinking, orientation, comprehension, calculation, judgment, speech and learning abilities. Clear consciousness, poor emotional self-control, social or motivational decline. Various factors such as intracranial diseases, metabolic diseases, nutritional deficiencies, intoxication, and psychosomatic disorders can lead to diminished ability to perform daily life and abnormal behavior. To address this symptom, the primary disease should be actively treated, and the patient should be trained in daily living skills and instructed to restore the corresponding abilities and change behavior. What is the differential diagnosis for patients with reduced ability to perform daily living and abnormal behavior? 1. Alzheimer’s disease: Early manifestation of memory impairment and increasing aggravation. Initially, there is only near-memory impairment, poor orientation, reduced work efficiency, misconstruction or fiction, on the basis of which the dementia gradually worsens, the calculation power is reduced, low judgment, slow reaction, comprehension difficulties, later appear speech disorders and aphasia, disuse, loss of recognition, etc.. Behavior disorders, stereotyped animals, occasional hallucinations and delusions, the age of onset in the 40 to 60 years. 2, Pick’s disease (Pick’s disease): the onset of the age of 40 to 60 years old, more women than men, the initial prominent symptoms for behavior disorders, patients less active and lazy, the daily life of others such as diet, sleep, clothing do not pay attention to, early personality changes, but also memory impairment. Patients lose their previous intelligence and work carelessly, and focal symptoms such as loss of use, reading, writing or recognition can appear early. The intellectual impairment is mainly difficulty in abstract thinking, and there is also memory loss. The dementia develops more rapidly and has a shorter course, and death occurs within one to several years, mostly due to secondary infection or failure. 3, Huntington’s disease (Huntington’s disease): the onset of dementia is usually very insidious, the first symptom is the reduction of work efficiency, the daily affairs can not be well handled. Cognitive slowness, intellectual impairment and memory deficits become apparent immediately after the onset of chorea, without aphasia or dysarthria. Concentration and judgment are progressively impaired, problem solving is poorly initiated, and the ability to calculate, near memory, and hand-eye coordination are poor. Depressive symptoms are very common, as well as personality disorders, and neurological symptoms, namely choreiform movements, are common in a few patients.