The peak age for the onset of schizophrenia is between 18 and 25 for men and between 26 and 45 for women. The onset may be sudden, over a period of days or weeks, or slow and insidious, over a period of years. The severity and types of symptoms can vary significantly among different people with schizophrenia. A person may have symptoms from one or all three groups. The symptoms are sufficiently severe as to interfere with the ability to work, interact with people, and care for oneself.
Delusions are false beliefs that usually involve a misinterpretation of perceptions or experiences.
For example, people with schizophrenia may experience persecutory delusions, believing that they are being tormented, followed, tricked, or spied on. They may have delusions of reference, believing that passages from books, newspapers, or song lyrics are directed specifically at them. They may have delusions of thought withdrawal or thought insertion, believing that others can read their mind, that their thoughts are being transmitted to others, or that thoughts and impulses are being imposed on them by outside forces. Thought disorder refers to disorganized thinking, which becomes apparent when speech is rambling, shifts from one topic to another, and loses its goal-directed quality. Speech may be mildly disorganized or completely incoherent and incomprehensible.