In outpatient work, we find a high number of patients with cognitive impairment combined with depression and anxiety, two disorders (cognitive and mood disorders) that have a common basis of prevalence and a high incidence. In 1996, IPA defined behavioraland psychological symptoms of dementia (BPSD), which are symptoms of disordered perception, thought content, state of mind, or behavior that frequently occur in patients with dementia. In contrast to the cognitive function of dementia, BPSD is treatable. As the symptoms of cognitive impairment increase, patients with dementia slowly become indifferent, slow, lack of energy, easily fatigued, lose enthusiasm for work, lose interest in activities they used to enjoy, and sometimes cry, laugh, and get angry easily; many patients do not pay as much attention to clothing and grooming as before, becoming sloppy, untidy, and unkempt; some become suspicious, stubborn, and calculating, with a wide range of clinical manifestations. The clinical manifestations vary widely. The co-morbidity of depression and anxiety disorders in Alzheimer’s patients has been reported to be 30%-53% abroad, and depression can aggravate the condition of dementia. Dementia presents with more mental retardation compared to geriatric depression. Studies have shown that depression is one of the symptoms produced by pathological changes in dementia, that patients with dementia are more likely to suffer from depression in early life, and that having depression in early life is one of the risk factors for developing dementia in later life. Anxiety is very common in patients with dementia, and patients who visit the clinic often have significant anxiety, manifested as irritability, irritability, frequent bathroom visits, panic attacks, and limb tremors. Some patients with Alzheimer’s disease may seem irritable in the evening or at night, such as fidgeting, walking back and forth, shouting or hallucinating. This phenomenon is called “twilight syndrome”, also known as “sunset phenomenon” or “sunset syndrome”. It is recommended that people with these symptoms come to the neurology department of Xuanwu Hospital as soon as possible, so that early intervention is half the battle.