Ganser syndrome is also called nonsense syndrome, balderdash syndrome, syndrome of approximate answers, hysterical pseudodementia, or prison psychosis. The disorder is named after German psychiatrist Sigbert Ganser who first observed the symptoms in three prisoners and subsequently published in a lecture in 1898.
The characteristic symptom of the disorder is distorted communication in the form of approximate answers (termed as Vorbeireden in literature) wherein a patient gives incorrect answers to simple questions but all the answers suggest an underlying understanding of the nature or content of the question. Other symptoms include impaired consciousness, fugue, somatization symptoms, hallucinations, and amnesia succeeding and in relation to events while symptomatic.
There is currently an ongoing debate on how to classify the disorder. The International Classification of Diseases (ICD-10) has it listed under dissociative disorders. Some do not consider it a mental illness in the first place, but a form of malingering (faking illness for gain) as it occurs most frequently in prisoners. In the Diagnostic and Statistical Manual for Mental Disorders (DSM) it was first classified in DSM-III as a factitious disorder (faking illness for no apparent gain), then it was reclassified under dissociative disorders in DSM-IV-TR then altogether unlisted in DSM-5.