Major mental illness. Schizophrenia is a mental illness that involves changes in perception, thoughts and behavior. Often the symptoms that occur are described as either acute or chronic. In the case of acute, onset of symptoms (hallucinations, delusions, incoherence) are sudden and may last for several weeks. In contrast, chronic symptoms are are similar, albeit long-term. (see www. Nimh. Nih. Gov).
Psychiatric disorder. It has characteristic of hallucination and delusion.