Could Dogs be the Portal to Early Detection & Prevention?
When I heard the story of the woman who could smell PD 1, it took a tenth of a second to realize a canine may be research partner I’d been looking for. Dogs are approximately 40 times better at detecting scents than humans. They are already the gold standard for bomb detection and are used in medicine to alert individuals with diabetes to drops in blood sugar and epileptics when seizures are pending. In my search for the perfect pooch, I went looking for a breed reputed to have a phenomenal sense of smell and capacity to communicate with their handler, a sense of discipline and an impressive work ethic. I was hoping for a size and disposition that could tolerate patients by day, children by night, and was small enough to travel, if necessary. It took me 18 months to meet a 4-month old Lagotto romingnolo2 named Cocoa and 4 days to train her.
Lagotto (Lake) dogs are from the Romingnolo region of Italy, where they have been bred for over 900 years to identify ripe truffles underground and signal to their handlers. These mid-sized dogs have hair (not fur), are smart, calm, and personable. Notable is her love of food- she’ll do anything you ask for a piece of dehydrated liver or lamb lung.
Learning to Identify the Scent of Parkinsonism
Cocoa started coming to our Parkinson’s clinic when she was only a few months old. For the first few days, I would sneak out into the waiting room and ask the patients with parkinsonism (PwP) to give her a treat when they met her. While everyone is welcome to pet her, she quickly learned to associate the scent of PwP with reward. By the fourth day in clinic, she was consistently identifying PwP without them having a treat in hand.
For over a year she has spent three days per week with me in the clinic where she meets over 40 people per day, approximately 10 of whom have some form of Parkinsonsim. She naps under the table while I see patients and when I open the door to the exam room between visits, she’ll go to the waiting room and sit on the foot of my next patient and wait for her reward. (People in the waiting room are warned and give permission.)
For a home training tool, I’ve collected swabs from several patients and mixed them together to ensure the scent of parkinsonism is captured. Initially, I hid container with the scent of PD under one of three bowls. She’d sniff around the edges and tell me which one had the sample hiding under it, at which time she’d get a treat. When she got good at that, we started playing hide-and-seek; I’d place the container in the bookshelf, under the rug, in the guitar case, in the couch cushion. Before she goes into the room, I’ll give her the cap of the scent of PD (to orient her) and send her into the room with the command, “Find it.” She naturally starts at one end of the room, circulates the periphery, and signals when she finds it.
To increase the number of samples she can screen in a single search, I built a track to hold multiple samples. In every round there is at least one sample from someone with clinically definite PD and one healthy control and a growing number of samples from individuals concerned they may have early symptoms of PD. Efforts are underway to obtain the necessary certifications to bring this test to the public. Like a DatScan, this test will not be able to diagnose Parkinsonism, but will be useful for ruling out Parkinsonsim in patients who don’t meet clinical criteria for diagnosis. Less expensive and easier to access than a DatScan, using canines to screen the human volatilome, or scent profile, has the potential to become a screening tool for individuals who may have a pre-motor form of parkinsonism.
Why does it matter if dogs can smell PD?
There is evidence PD can be slowed with lifestyle modification. There are a lot of people in their 40s and 50s walking around with non-motor symptoms of parkinsonism, they just don’t know it yet. If individuals with disrupted sleep, fatigue, sexual dysfunction, irritable bowel syndrome, and loss of smell could be screened and alerted early in the course of their disease, even modest changes in lifestyle could translate to clinically meaningful outcomes over time. (Figure 1)
Early Intervention Makes Disease-Modification More Meaningful
This figure shows how even a modest reduction in the rate of progression early in the disease could translate to fewer symptoms and higher quality of life over time. The solid black line is the average PRO-PD score at diagnosis is 637 and increases at a rate of 33 points per year, using data from over 1000 individuals with PD.3 The dotted lines show what the course of progression might look like if an individual reduced the rate of progression by 50%. The red circle is where we hope the dogs will be most useful.
Even a 5 year delay in progression would drastically reduce the number of people affected, saving the health care system billions and preserving the quality of life of affected individuals.
Insight into disease: If we can learn what the dogs are smelling, it may provide clues related to our understanding of disease. For instance, the current dogs can’t distinguish between different forms of Parkinsonsim. Whether someone has idiopathic PD, multiple system atrophy, dementia with Lewy bodies, or kufor-rakeb, the dogs say ‘yes.’
Where do we go from here?
We’re working with our ethics board and scientific advisors to develop a kit that is useful to patients, clinicians, researchers, and ultimately serves as a portal to prevention. We aren’t in a position to be able to tell anyone what their results are, because we don’t yet know what the results mean.
A whole field is opening up with different teams pursuing different interests; while some work to characterize the scent, others are learning about the stability of samples, how best to train dogs to give reproducible and consistent results, or finding and following a pre-motor cohort over time to see if/when they develop symptoms.
Early detection will be essential for PD prevention, a target that has evaded us for 200 years. It now seems that with a little bit of inter-species collaboration, a missing piece of the puzzle might be right under our nose!
References
- The Woman Who Can Smell Parkinson's Disease|Documentry
- American Kennel Club Breeds: Lagatto
- Use of a self-rating scale of the nature and severity of symptoms in Parkinson's disease(PRO-PD): Correlation with quality of life and existing scales of disease severity
- Parkinson's Detection Dogs (PADs) Update
- Dogscould sniff out Parkinson's disease years before symptoms appear
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Laurie Mischley ND, MPH, PhD presented at the Fourth World Parkinson Congress in Portland, Oregon. As a clinical researcher, she has worked with the FDA, NIH, and the Michael J. Fox Foundation to administer intranasal glutathione, (in)GSH, to individuals with PD. Drawing on expertise in epidemiology, nutrition, neurology, and naturopathic medicine, she is attempting to determine whether (in)GSH boosts brain glutathione and improves health, which she lectured on at the WPC 2016. She founded the social purpose corporation, NeurRx, that is working to develop a canine-based PD screening tool; developed an outcome measure to assess PD severity; and is author of the book Natural Therapies for Parkinson’s Disease. Dr. Mischley maintains a small clinical practice at Seattle Integrative Medicine focused on nutrition and neurological health.
Ideas and opinions expressed in this post reflect that of the author(s) solely. They do not reflect the opinions or positions of the World Parkinson Coalition®