Personality disorders are chronic mental disorders. People with these disorders have behaviors that make it hard for them to function in society. Affected people usually do not learn from mistakes and do not adapt well to changes in their lives. These disorders usually start before or during the teenage years.
Most people can live fairly normal lives with mild disorders. But when stress increases, symptoms often increase and begin to interfere with the person's ability to function.
The exact cause of personality disorders is unknown. Some theories include: