Can Sniffer Dogs be used in the Diagnosis of Parkinson’s? Learn more about how Sniffer dogs can link to Parkinson's research in this fascinating article below.
An interesting study was recently published in Movement Disorders (the official journal of the International Parkinson and Movement Disorder Society). This study, carried out in China, aimed at testing the sensitivity of using sniffer dogs to accurately diagnose Parkinson’s.
One of the challenging elements of Parkinson’s has long been that there are no available sensitive biochemistry or radiological tests to determine the diagnosis, which is still made based on the clinical picture of the signs and symptoms and the expertise of the examining Dr.
The authors of this study report the accuracy of clinical diagnosis as 81% when compared to pathological accuracy. In recent years, we have read of the anecdotal feedback on a lady in Scotland who claims to be able to smell the presence of Parkinson’s. This has led to further studies.
The study of sniffer dogs was carried out in four tertiary medical centres in China and evaluated the accuracy of the dogs in picking between:
- 109 medicated people with Parkinson’s
- 654 people without Parkinson’s
- 37 people with a diagnosis of Parkinson’s but not yet on medication
- 185 non Parkinson’s control participants.
Once the participants were selected for the study, two medical gauze swabs were used to brush their upper back and these swabs were transported to the testing centres. Three Belgian Malinois sheepherder dogs, previously trained in detecting human disease (in particular detecting Parkinson’s) were used in the study. The study used a double blind method- neither the dog handler nor the research assistant (nor the dogs) knew the allocation or placement of the samples from known Parkinson’s subjects. If two or three of the dogs indicated a positive sample (by lying in front of the sample), it was judged to be a positive detection. If only one dog gave a positive indication, this was judged to be indeterminate.
Results:
- Of the 109 medicated People with Parkinson’s 99 tested positive by two or three dogs, three tested positive by one dog only and seven were negative by all three dogs - sensitivity of 91% and accuracy of 95%.
- Of the 654 people without Parkinson’s, 570 tested negative by two or three dogs, 31 tested positive by two to three dogs and 53 were positive by one dog only.
- Of the 37 people with a diagnosis of Parkinson’s but not yet on medication, 33 tested positive by two to three dogs, three tested positive by one dog only and one was negative by all three dogs - sensitivity of 97% and accuracy of 86%.
The study identified that the reported smell associated with Parkinson’s is independent of Parkinson’s medications. This smell is more easily detected by dogs as they have 1 million times more olfactory function than humans. Previous studies have indicated that the smell is associated with sebum (a waxy substance on our skin). This was an interesting study, and if you are interested the dogs involved were named - Xiu-Ying, Zhong-Lang and Lie-Yan.
Reference: Gao, C.Q. et al. Sensitivity of Sniffer Dogs for a Diagnosis of Parkinson’s: A Diagnostic Accuracy Study. Movement Disorders Vol. 37, No 9 2022. pp 1807-1816.