Ganser's syndrome is a rare disorder in which the affected person gives approximate answers to questions that have right and wrong answers, such as "What is 5 minus 3?"
Although this disorder was previously classified as a factitious disorder, the American Psychiatric Association has redefined Ganser's syndrome and placed it in the category called "Dissociative Disorder Not Otherwise Specified." Sometimes called "the syndrome of approximate answers," Ganser's syndrome is most often seen in male prisoners. In the past, this was so much the case that early clinicians called the syndrome "prison psychosis," despite the fact that it is not a true psychosis. (Psychosis is characterized by a radical change in personality and a distorted sense of reality.) The disorder has also been referred to as hysterical pseudodementia, due to the resemblance of responses to those of demented patients. However, data on the prevalence of the syndrome and on links within families have not been gathered and analyzed.
Ganser's syndrome is usually sudden in onset and, like malingering, seems to arise in response to an opportunity for personal gain or the avoidance of some responsibility. The patient will offer nearly correct replies when asked questions about facts of common knowledge, such as the number of days in a year, the number of months in a year, subtracting seven from 100, the product of four times five, etc. To such questions, the patient may respond by stating that there are 360 days in a year, 11 months in a year, 94 for the result of subtracting seven from 100, and that 21 is the product of four times five. These persons appear to have no difficulty in understanding questions asked, but appear to provide incorrect answers deliberately.
This syndrome is seen in conjunction with a preexisting severe personality disorder. However, unless the patient is willing to admit to the manufactured nature of the symptoms, or unless there is conclusive objective evidence contradicting the syndrome, determining whether the patient has a true disorder may be impossible. As with its sudden onset, disappearance of the symptoms can be just as fast. However, symptoms can also appear to worsen if the patient believes someone is watching. When reviewing a case of Ganser's syndrome, the clinician must consider factitious disorder and malingering as alternative diagnoses.
American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders. 4th edition, text revised. Washington, DC: American Psychiatric Association, 2000.
Kaplan, Harold and Benjamin Sadock. Synopsis of Psychiatry. 8th edition. New York, N.Y.: Lippincott, Williams and Wilkins, 1997.
Jack H. Booth, Psy.D.