A bridge friend recently consulted me via QQ that his mother, who might have caught a cold due to the change of weather, had hallucinations at night and always saw something that others could not see. After her health condition got better, the above symptoms were gone. Therefore, he was worried and had many questions. His family has no history of mental illness, so why would his mother have psychotic manifestations? Is it possible that his mother is suffering from Alzheimer’s disease? In the spiritual dialogue on our website, a Mr. Li also raised a similar question. His mother used to suffer from schizophrenia and had been taking antipsychotic medication, and her condition was very stable, but recently, she had “gradually become blurred” and her symptoms were different from the previous onset. Through further questioning and observation, the presentation of the two patients was consistent with the diagnosis of “delirium in old age. Let’s have a brief understanding of what delirium is. Delirium, also known as acute encephalopathy syndrome or acute reversible disorder of consciousness, occurs mostly due to various physical diseases. Delirium is characterized by cloudy consciousness, narrow range of consciousness, disorientation, incoherent thinking, and mostly accompanied by psychomotor excitement, i.e., behavioral disturbances, and is therefore also called a state of delirium. Delirium, although it can occur at any age, is more common over the age of 60. Delirium in the elderly is a common symptom in clinical departments that mainly serve elderly patients, such as geriatric departments, cadre departments and their wards, medical institutions that specialize in cerebrovascular disease, cardiovascular disease and metabolism, and elderly welfare homes and nursing homes. Most of the causes of delirium in the elderly are two important aspects: biological factors and psychosocial factors. Decline in physiological functions: With ageing and physical diseases, the body tissues, organs and systems of the elderly are gradually aging, with reduced adaptability and resistance, and decreased stability of the body. These are the physiological basis for delirium. Physical diseases: cerebrovascular disorders, degenerative brain disorders, metabolic encephalopathy, systemic infections, and advanced cancer directly or indirectly affect the blood circulation and metabolic function of the brain, leading to delirium. Drug-induced delirium: As we age, the absorption and metabolic processes as well as excretion become slower during the use of drugs. Common drugs include: anti-Parkinsonian drugs, sedative-hypnotics, antipsychotics, antidepressants, adrenocorticotropic hormones, as well as hypoglycemic drugs, antibiotics, etc. Psychosocial factors: Older people not only have physical changes, but also have significant changes in their psychological and personality. Especially on the basis of inner imbalance such as declining economic level and social status after retirement, they are prone to defensive psychology. Widowhood, living alone, and fear of death are also prone to delirium. It is especially worth mentioning that delirium in the elderly is closely related to dementia. Not only is the frequency of delirium in demented elderly high, but also, if the delirium lasts for a long time, it is often found to have mild dementia after the return of normal mental faculties. In conclusion, the elderly are more prone to delirium than young adults on the basis of aging physiological and psychological functions, especially when they are in a state of somatic disease or stress, especially when they have cerebrovascular disease, cardiovascular disease, and dementia.