Can Dogs Sniff Out Parkinson’s Disease?

As if we needed any more reasons to appreciate our dogs, new research suggests they might be able to detect Parkinson’s disease.

More specifically, a new preprinted study, which has yet to work its way through peer review, shows that dogs can sniff out PD better than most medically established tests.

A Struggle to Diagnose Parkinson’s

PD, a chronic degenerative neurological disorder, hits people differently, with disparate progression rates. As a result, it remains a struggle for doctors to diagnose accurately.

In fact, a recent poll from the Parkinson’s Disease Society of the United Kingdom found that among the 2,000 people it surveyed, “more than a quarter – 26% – reported they were misdiagnosed with a different condition before receiving the correct Parkinson’s diagnosis.”

The Parkinson’s UK survey also backed up earlier research that women received a misdiagnosis more than men. Older patients – between 51 and 60 – also have trouble getting a proper determination.

And there’s still no single definitive test to identify the disease. But scientists have identified “evidence of volatile organic compounds in sebum that are unique to patients with PD.”

Smells Like Hope

As a result, researchers Lisa Holt and Samuel Johnston figured that if a gland secretion reveals a link to PD, then a dog might be able to smell it. After all, a dog’s sense of smell is at least 100,000 times better than a human’s.

And dogs have been helping diabetes patients keep an eye (or a nose) on their glucose levels for years. Previous research has also shown that dogs can detect several types of cancer.

So, the pair designed a random, handler-blind, controlled study that included nearly two dozen dogs – including multiple breeds. The dogs were of different ages and came from a variety of environmental backgrounds.

This particular study focused on the last two years of a seven-year program. It covered 200 total working session days between 2021 and 2022.

Dogs Show Promise

The results exceeded expectations.

“The 23 dogs were 89 percent sensitive and 87 percent specific to an olfactory distinction between PD-positive and PD-negative human donor samples. Ten of the 23 dogs averaged 90% or higher in both sensitivity and specificity,” the authors wrote. “For first-time exposures, the 23 dogs collectively averaged 86% sensitivity and 89% specificity.”

“It takes approximately six to eight months of training with the dogs attending three to four days per week,” Holt, who’s a certified trainer and founder of PADs for Parkinson’s, told IFLScience in an interview. “The dogs are trained to distinguish the difference between PD-positive sebum samples and PD-negative sebum samples. These samples have been collected from individuals with and without Parkinson’s Disease […] using T-shirts that sample donors sleep in overnight, or cotton swabs collected from the upper back and lower backside of the neck.”

Further Reading

3 Key Updates in Parkinson’s Disease

Parkinson’s Incidence In the U.S. Nearly 50% Higher than Previous Estimates

Psychiatric Issues in Parkinson’s Disease: A Practical Guide