Schizophrenia is a mental disorder that affects how someone thinks and behaves. It can cause people to think and act in unusual ways. For example, someone with schizophrenia might hear voices that aren't there or have strange, confusing thoughts. They might withdrawal and seem uninterested in things that used to make them happy, or suspicious of people they used to be close to, or have problems concentrating or thinking logically. Treatment includes medications and therapy to help people better manage their symptoms.