Patients with mental disorders can have hallucinations, and mental disorders are subdivided into organic mental disorders and functional mental disorders. The former refers to mental disorders with a clear etiology to follow, such as patients with definite structural or functional brain damage, commonly seen in cerebral infarction, cerebral hemorrhage, brain tumor, encephalitis, and advanced stages of degenerative diseases, such as Alzheimer’s and Parkinson’s disease. This type of mental disorder, cranial MRI or CT, can reveal abnormal lesions in the brain. Functional psychiatric disorders are mostly seen in primary psychiatric disorders, such as schizophrenia, bipolar disorder, depression, etc. In these patients, structural damage is difficult to detect on brain examination.