Why does a person's personality change greatly?

The reason why a person's personality suddenly changes:

1. Physical diseases, especially brain diseases, such as hepatic encephalopathy, pulmonary encephalopathy, viral encephalitis, hypertensive encephalopathy, etc. The damage of brain nerve cells interferes with the normal function of the brain, leading to personality changes.

2. Mental illness, such as schizophrenia patients suddenly become withdrawn, sensitive and suspicious, manic patients suddenly become excited, talkative and easily angered, and depressed patients suddenly become silent and pessimistic.