Even though Parkinson’s disease is incurable, nowadays doctors are able to favorably influence the course of the disease, so that patients are able to enjoy a high quality of life for many years. In order to fight against the destruction of brain cells in Parkinson’s it is necessary for doctors to detect the disease early, but unfortunately only very few adequate early detection methods are available.

Researchers have now discovered that the sense of smell provides valuable indications. Hyposmia, i.e. losing the ability to smell for no known cause could be a markers for the non-motor signs of Parkinson’s disease. Dr Ulrich Liebetrau, chief physician for Parkinson’s consultations at the Neurological Department of Kliniken der Stadt Köln, declared at the 22nd Meeting of the European Neurological Society (ENS) in Prague: “Smelling tests in doctors’ offices are suitable for detecting hyposmia but so too are tests conducted in public places such as pedestrian zones.”

Parkinson’s is a very common neurological slowly progressive disease that usually affects individuals aged between 50 and 60 years. In Germany alone there are about 300,000 people diagnosed with Parkinson’s. Scientists still remain uncertain for the reasons of cell death occurring in the substantia nigra in the basal ganglia of the brain of Parkinson’s patients, but suspect that genetic factors may be involved. The cell death causes a shortage of dopamine, a neurotransmitter, which leads to loss of control over voluntary and involuntary movements. German neurologists from Cologne have now tested a new early detection method for subtle signs of Parkinson’s which focuses on the partial loss of the sense of smell, which they based on previous studies that demonstrated that one in ten people with hyposmia develop Parkinson’s in later years.

Dr Liebetrau explained: “Our objective was to reach as many people with hyposmia as we possibly could.”

The team used an unusual method for their trial. They performed a public smelling test on a Saturday in a banqueting hall in Cologne’s pedestrian district that is well known. Liebetrau described the requirements the venue needed to fulfill, saying:

“For people to accept the test we were offering, the location had to be central and familiar to everyone. Another important factor was having private places to withdraw. But tents would have detracted from the seriousness of the endeavor.”

They asked 187 participants to smell vanilla, lemon, cloves and lavender to smell. Overall, 46 participants were identified as having hyposmia, who were all offered a follow-up at the City of Cologne Clinics (Kliniken der Stadt Köln). Dr Liebetrau explained: “The test was to be followed up by a professional examination done by neurologists and ENT specialists at a separate time and place. After all, hyposmia can be a sign of any number of diseases.”

The result revealed that three of the 46 individuals with hyposmia were diagnosed with Parkinson’s, even though they had no former knowledge prior to the test that they were affected by the disease.

One of the key advantages of low-threshold tests is that diseases that would otherwise go undetected are identified early, which also prevents these diseases from becoming chronic. Early diagnosis is advantageous, even if they involve severe neurological disorders like Parkinson’s.

Dr Liebetrau declared: “There is no cure for Parkinson’s but new drugs such as Rasagilin can have a demonstrably positive effect on the course of the disease, especially if treatment is started early. Further research is needed to determine whether that also applies to early stages of the disease.”

The researchers conclude that olfactory dysfunctions are not just irritating; they also provide an opportunity to detect Parkinson’s in the early stages of the disease and recommend to use hyposmia as an early indicator of Parkinson’s. Liebetrau concludes: “Physicians should ask more frequently about olfactory dysfunctions and conduct simple tests, for instance with coffee or spices. If hyposmia is suspected, a confirmation test must be carried out.” He added that public smelling tests are especially suitable for raising awareness of hyposmia.

Written By Petra Rattue