The clinical manifestations of delirium include attention disorder, consciousness disorder and other symptoms, which are relatively common in the elderly. 1. Attention deficit: It is mainly manifested as a decrease in the ability to orient, focus, maintain and change attention, which leads to the patient often staying in the previous question during the conversation and not being able to shift attention appropriately with the change of the question, so the question asked to the patient often needs to be repeated, and the patient can easily be distracted by the influence of irrelevant stimuli. 2. Impaired consciousness: This is characterized by a decreased level of consciousness and a diminished ability to orient to the environment and sometimes even to oneself. 3. Other symptoms: learning or memory disorders; disorientation disorders, especially time and place orientation disorders; perceptual disorders, such as delusions or hallucinations; sleep-wake disorders, including daytime sleepiness, nocturnal agitation, difficulty in falling asleep, and wakefulness throughout the night, with some patients experiencing circadian reversal; and emotional-behavioral disorders, such as anxiety, depression, fear, irritability, anger, euphoria, and affective indifference. Delirium is a syndrome, often accompanied by extensive cognitive impairment and corresponding mental and behavioral symptoms. When delirium symptoms occur in the elderly, they should seek prompt medical attention to clarify the cause of the disease and then treat the symptoms.