Paranoia, in psychology, is a state of mind characterized either by delusions of grandeur or by an unfounded belief that one is being persecuted by others, or by both. Although even healthy individuals may be subject occasionally to mild forms of paranoia, those with chronic cases tend to form rigid belief systems, often misinterpret the behavior of others as confirming their delusional views, and exhibit a great deal of anger and hatred. It is unknown what causes the escalation to paranoia from the natural "vigilance" with which most people regard their sometimes-hostile environment. Some theorists suggest, however, that paranoid individuals project onto others attributes that they dislike in themselves. Organic causes are also possible. Social isolationÑwhether by choice or circumstanceÑseems to exacerbate paranoia.
The diagnostic category called paranoid disorder encompasses acute delusional paranoia cases of at least a week in duration, which may be brought about by other emotional problems. Paranoid personality disorder is another diagnostic category encompassing persons with chronic but nondelusional symptoms of paranoia. The usual course of treatment for both is psychotherapy. Paranoia is also a characteristic of a subtype of schizophrenia known as paranoid schizophrenia. In addition to having the symptoms described for paranoid disorder, persons with paranoid schizophrenia have frequent auditory hallucinations that reinforce their delusions. The course of treatment for paranoid schizophrenia often includes drug therapy.