Our response to COVID-19

We're supporting people to maintain their wellbeing and manage isolation.

Olfactory functioning

What is olfactory functioning? 

The olfactory system is the sensory system used to interpret and perceive smell. Olfactory functioning is hierarchical and involves lower-order processing (detection of the stimulus) and higher-order processing (discrimination and identification of the stimulus). Odour detection occurs at the lowest chemical concentration needed to register an odourant. Odour discrimination involves comparing the differences between multiple stimuli, judging odours as pleasant or unpleasant, or comparing the relative concentration of odours. Odour identification draws on a person’s knowledge and memory to correctly label the smell.

What is the evidence for altered olfactory functioning in schizophrenia?

Moderate to high quality evidence suggests a medium to large effect of impaired odour detection, identification, and discrimination in people with schizophrenia compared to people without schizophrenia. A longer duration of illness, taking first generation rather than second generation antipsychotics, and older age were all associated with more impairment in patients. Males and greater smoking rates found less impairment n patients. Moderate to high quality evidence suggests there is impaired olfactory identification, but not acuity, in people at high clinical or high familial risk of schizophrenia.

September 2020

Last updated at: 12:44 am, 3rd September 2020
To view documentation related to this topic download the files below
Fact Sheet Technical Commentary

NeuRA Libraries

Title Colour Legend:
Green - Topic summary is available.
Orange - Topic summary is being compiled.
Red - Topic summary has no current systematic review available.