Source : FISH ’S Clinical psychopathology

Smell (olfactory)

Hallucinations of odour can occur in schizophrenia and organic states and, uncommonly, in depressive psychosis. It may be difficult to be sure if there is a hallucination or an illusion. There may also be a problem distinguishing olfactory hallucination from delusion since there are some people who insist that they emit a smell. It is important to ascertain if they actually smell this odour, since many seem to base their belief on the behaviour of other people who, they say, wrinkle their noses or make reference to the smell. Some patients with schizophrenia claim that they smell gas and that their enemies are poisoning them by pumping gas into the room. Episodes of temporal lobe disturbance are often ushered in by an aura involving an unpleasant odour such as burning paint or rubber. At times, the hallucination may occur without any fit so that the patient then complains of a strange smell in the house. For example one patient with a temporal lobe focus had no fits but, from time to time, would complain of a smell of stale cabbage water in the house and would turn the house upside down trying to locate the offending object. Sometimes the smell may be pleasant, for example when some religious people can smell roses around certain saints; this is known as the Padre Pio phenomenon.