Schizophrenia is a medical illness that debilitates and interferes with normal every day functioning. People with schizophrenia may hear voices other people don't hear or believe that others are reading their minds, controlling their thoughts, or plotting to harm them. These experiences are terrifying and can cause fearfulness, withdrawal, or extreme agitation. People with schizophrenia may not make sense when they talk, may sit for hours without moving or talking much, or can seem perfectly fine until they talk about what they are really thinking.