An Australian team from the University of Melbourne examined a group of people deemed to be at ultra high risk of developing psychosis and found those that went on to develop schizophrenia, rather than other forms of psychosis, all displayed the inability to identify smells. This deficit was present before the onset of any significant clinical symptoms of psychosis.
The study, the first of its kind, is published in the October 2003 American Journal of Psychiatry. The research has also reignited the academic debate regarding the influence of genetics versus social factors on the development of various forms of psychosis.
It has long been known that people suffering schizophrenia and other forms of psychosis are often unable to correctly identify smells. That is, pizza may be mislabelled as orange, or bubblegum as smoke. Before the current findings, however, it was unknown if this difficulty developed later, as a result of the progression of the disorder, or well before any symptoms of psychosis became obvious.
Dr. Warrick Brewer and Associate Professor Christos Pantelis from the University's Departments of Psychiatry and Psychology tested their theory that a vulnerable sense of smell could be used as a possible diagnostic tool for psychosis. The search for current diagnostic methods such as brain imaging, clinical symptoms and genetics has, to date, proved unreliable.
"An accurate and reliable diagnostic tool for schizophrenia could allow for early treatment or prevention and minimise the extensive and significant distress to those in the community directly and indirectly affected," says Brewer.
Their results suggest a promising discovery of the first potential marker for schizophrenia, and possibly for other psychoses.