Olfactory and Gustatory Hallucinations

Hallucinations Opens in new window of smell and of taste frequently occur together, and it may be difficult or impossible to distinguish each from the other. This is not surprising, as a lot of what a layperson ascribes to taste is actually smell: ‘the eucalyptus fragrance of this wine from the Barossa Valley’.

Olfactory Hallucinations

Olfactory hallucinations may range from the experience of something smelling to the subject complaining that s/he smells unpleasantly.

Olfactory sensation or memory is often associated with powerful emotional resonances; it is not surprising therefore that hallucinations are also involved with a strong affective component.

Olfactory hallucinations are seen in schizophrenia Opens in new window, in depressive illnesses (where the smell is described as unpleasant or repulsive to others).

Olfactory hallucinations are also prominent in epilepsy Opens in new window and in some organic states. The patient has a hallucination of smell.

The smell may or may not be unpleasant, but it usually has a special and personal significance (Aggernates’ quality of relevance), for example it may be associated with the belief that people are pumping a poisonous or an anesthetic gas into the house, which the patient alone can smell.

This particular patient killed himself. He felt that he created such a stench that he was intolerable in any reasonable society.

Sometimes, patients misinterpret and overvalue Opens in new window normal body odours. A delusion Opens in new window in which a patient believes himself to smell malodorously without an accompanying olfactory hallucination is quite common in schizophrenia Opens in new window and related paranoid states.

Olfactory hallucinations occur in epilepsy, especially in association with a temporal lobe focus, and commonly form the aura (or earliest phase) of such fits.

Visual Opens in new window, auditory Opens in new window, gustatory (see below) and visceral hallucinations Opens in new window also occur in temporal lobe epilepsy.

Gustatory Hallucinations

Gustatory hallucinations are seen in various conditions. In schizophrenia Opens in new window, they sometimes occur with delusions Opens in new window of being poisoned.

There may be a persistent taste, for example onions, a metallic taste or some more bizarre type of taste. In depression and in schizophrenia, the flavor of food may disappear altogether or become unpleasant.

Changes in gustatory perception may occur with some organic states, such as temporal lobe epilepsy, and also with some psychotropic drugs, for example lithium carbonate or disulfiram. It is often difficult to describe how this disturbance of taste is mediated and, therefore, whether it is hallucinatory or not.