Mass Screening Smell Test Discovers Early Parkinson's Cases

Daniel M. Keller, PhD

June 22, 2012

June 22, 2012 (Prague, Czech Republic) — A 1-day mass public screening testing people's ability to detect 5 different scents identified 3 potential cases of early Parkinson's disease (PD). An olfactory deficit is an early symptom of PD.

The screening also turned up a substantial number of people with hyposmia caused by a variety of other conditions.

Clinicians in Cologne, Germany, in cooperation with FARINA, manufacturer of eau de cologne since 1709, set up the Cologne Public Smelling Project in a pedestrian zone of the central city hall one Saturday in September 2011 to screen residents for hyposmia.

Ulrich Liebetrau, MD, from the Department of Neurology at the Klinikum Köln-Merheim, presented study results here during a poster presentation at the 22nd Meeting of the European Neurological Society.

Dr. Ulrich Liebetrau

Joint Effort

The project, a joint effort between the departments of neurology and ear, nose, and throat of the city hospital, was publicized on local radio and television and in newspapers. It attracted 187 people, who stopped by the test site and were screened; 46 failed the smelling test. Each test required about 15 minutes to administer.

Specialists from FARINA created compounds with the smells of coffee, lemon, clove, vanilla, and lavender, which were presented to participants in neutral brown vials. Testers considered correct identification of fewer than 3 smells as an indicator of hyposmia.

All participants had the opportunity to speak with a physician. Those who failed the test were invited to have a free examination in the outpatient clinic of the hospital, where further testing with 12 different "sniffin' sticks" was done to confirm the initial results.

As a group, the 46 participants who failed the initial test were older (average age, 64.8 years) compared with the 141 people who passed the smell tests (average age, 53.8 years). Forty participants accepted the invitation for further testing; 35 had abnormal results on more detailed smell tests.

Three participants were identified on clinical grounds as having early PD. They, and none of the others, had other signs of PD, such as rapid eye movement sleep behavior disorders. Of 3 people identified with early PD, 1 is now receiving drug therapy, and 2 still do not have motor signs so are not taking medication.

Dr. Liebetrau said the project received significant media attention and highlighted hyposmia as an important symptom of various disorders. From results of the screening, he said the prevalence of hyposmia in the cohort tested, presumably representative of the population of Cologne, was at least 15% to 20%.

"Hyposmia is well known as an early nonmotor sign of Parkinson's disease," Dr. Liebetrau said. The finding of 3 early cases of PD on clinical grounds is consistent with previous literature showing that 10% of patients with hyposmia will eventually develop PD.

In general, many people with hyposmia do not know that their sense of smell is diminished. Besides detecting early potential PD cases, another goal of the screening was to estimate the prevalence of hyposmia in the general public.

Dr. Liebetrau concluded that screening for hyposmia appears to be a valuable tool for the early detection of PD, and that significant media attention to the screening raised public awareness of hyposmia as an important symptom of a variety of medical disorders, so in general, he would recommend public screenings.

"First of all, people should know that hyposmia is not just hyposmia but may be the beginning of a serious disease or [may] cover a serious disease," he said. Second, "hyposmia is a sign of parkinsonism, and if you make such examinations in the public, you maybe find some unknown Parkinson's."

On the other hand, most cases of hyposmia were the result of other causes. Dr. Liebetrau said that Cologne often experiences wet weather, and chronic nasal or sinus inflammation was the most common reason for hyposmia. Five individuals with hyposmia of unknown cause are being followed in his department. No difference between smokers and nonsmokers was noted in the smell test results.

Ethical Issues?

Poster session moderator Kailash Bhatia, MD, DM, from the Institute of Neurology at University College London, Queen Square, London, United Kingdom, asked Dr. Liebetrau if it is ethical, in a mass screening setting, to discover potential PD cases and possibly cause people to worry, especially because presently, no neuroprotective drugs are available.

Dr. Liebetrau said that it is not unethical because the tests reveal only hyposmia, not PD or any other diagnosis. "We just wanted to say, 'If you are suffering from hyposmia, you may have another disease in the background.' We didn't say, 'Come to us, and we'll see whether you have parkinsonism,' " he explained.

Speaking with Medscape Medical News, Dr. Bhatia expanded on the ethical issue. "If you're picking up at random people on the street and asking them to smell, and you know that in a proportion of them, a difficulty in smell could be an indicator of a degenerative condition like Parkinson's disease, the ethical issue is these people are at the moment asymptomatic, and is it right to alarm them about this possibility in the future?" he asked.

He said it was not clear from Dr. Liebetrau's presentation whether participants were informed about the possible outcomes and implications of the testing, and if they had then given consent.

"The main thing is that we don't have a disease-modifying or a disease-preventing drug, so although this sort of a study is very useful on a properly designed trial basis, I'm not sure about picking up people on the street in terms of the ethical issues," Dr. Bhatia said.

The screening and a small gift to participants were supported by FARINA. Dr. Liebetrau and Dr. Bhatia have disclosed no relevant financial relationships.

22nd Meeting of the European Neurological Society. Abstract P-407. Presented June 10, 2012.