Schizophrenia is a serious psychiatric disorder that affects more than 1 percent of the population, according to the American Psychiatric Association. People with schizophrenia slowly lose contact with reality and often have delusions or hallucinations. There are misconceptions about this mental illness. For example, some people think schizophrenia is a split personality. In fact, schizophrenia and split personality, properly termed “dissociative identity disorder,” are two different disorders.