How can you tell if you have schizophrenia? Schizophrenia is a serious mental illness that impacts the way people think, feel, and behave. Some symptoms of schizophrenia are hallucinations, delusions, problems thinking clearly, and disorganized behavior. With the right diagnosis and treatment, many people with schizophrenia can live in their communities, have positive relationships, maintain employment, and continue to work towards their goals.