Schizophrenic Disorders

Psychotic disorders such as schizophrenia are a group of serious illnesses that affect the mind. These illnesses alter a person's ability to think clearly, make good judgments, respond emotionally, communicate effectively, understand reality, and behave appropriately. When symptoms are severe, people with psychotic disorders have difficulty staying in touch with reality and often are unable to meet the ordinary demands of daily life. However, even severe psychotic disorders usually are treatable.

An example of this type of disorder is Delusional Disorder

http://www.webmd.com/schizophrenia/guide/mental-health-schizoaffective-disorder