Psychosis may be a symptom of a mental illness, such as schizophrenia, bipolar disorder, or severe depression. However, a person can experience psychosis and never be diagnosed with schizophrenia or any other disorder. For older adults, psychosis symptoms can be part of a physical or mental illness that emerges later in life. More @Wikipedia
Hover over any link to get a description of the article. Please note that search keywords are sometimes hidden within the full article and don't appear in the description or title.