Based on the DSM-5, this disorder is called schizophrenia (American Psychiatric Association, 2013). The cause of schizophrenia is still unknown, however, there are many different theories about its cause. . Heredity, environment, and differences in brain chemistry are the main thoughts on the causes of schizophrenia. This disorder only affects 1% of the total population. When it comes to heredity, the percentage goes up to 10% if a person has a first-degree relative, such as a parent or sibling, with schizophrenia. If a person is an identical twin, the percentage increases from 40% to 65%. Based on the percentage variation, scientists concluded that the genes tend to develop schizophrenia. The development of this disease is also linked to environmental changes such as viral infection or very stressful events. Finally, schizophrenia can be caused by changes in brain chemistry. An imbalance of chemicals in the brain, neurotransmitters like serotonin and dopamine, affects how the brain responds to stimuli (schizophrenia). SYMPTOMS: Schizophrenia has three types of symptoms....