Her Incredible Sense of Smell Helped Scientists Develop the First Parkinson's Test
Forty years ago, Joy Milne, a nurse from Perth, Scotland, noticed a musky odor coming from her husband, Les. At first, Milne thought the smell was a result of bad hygiene and badgered her husband to take longer showers. But when the smell persisted, Milne learned to live with it, not wanting to hurt her husband's feelings.
Twelve years after she first noticed the "woodsy" smell, Les was diagnosed at the age of 44 with Parkinson's Disease, a neurodegenerative condition characterized by lack of dopamine production and loss of movement. Parkinson's Disease currently affects more than 10 million people worldwide.
Milne spent the next several years believing the strange smell was exclusive to her husband. But to her surprise, at a local support group meeting in 2012, she caught the familiar scent once again, hanging over the group like a cloud. Stunned, Milne started to wonder if the smell was the result of Parkinson's Disease itself.
Milne's discovery led her to Dr. Tilo Kunath, a neurobiologist at the Centre for Regenerative Medicine at the University of Edinburgh. Together, Milne, Kunath, and a host of other scientists would use Milne's unusual sense of smell to develop a new diagnostic test, now in development and poised to revolutionize the treatment of Parkinson's Disease.
"Joy was in the audience during a talk I was giving on my work, which has to do with Parkinson's and stem cell biology," Kunath says. "During the patient engagement portion of the talk, she asked me if Parkinson's had a smell to it." Confused, Kunath said he had never heard of this – but for months after his talk he continued to turn the question over in his mind.
Kunath knew from his research that the skin's microbiome changes during different disease processes, releasing metabolites that can give off odors. In the medical literature, diseases like melanoma and Type 2 diabetes have been known to carry a specific scent – but no such connection had been made with Parkinson's. If people could smell Parkinson's, he thought, then it stood to reason that those metabolites could be isolated, identified, and used to potentially diagnose Parkinson's by their presence alone.
First, Kunath and his colleagues decided to test Milne's sense of smell. "I got in touch with Joy again and we designed a protocol to test her sense of smell without her having to be around patients," says Kunath, which could have affected the validity of the test. In his spare time, Kunath collected t-shirt samples from people diagnosed with Parkinson's and from others without the diagnosis and gave them to Milne to smell. In 100 percent of the samples, Milne was able to detect whether a person had Parkinson's based on smell alone. Amazingly, Milne was even able to detect the "Parkinson's scent" in a shirt from the control group – someone who did not have a Parkinson's diagnosis, but would go on to be diagnosed nine months later.
From the initial study, the team discovered that Parkinson's did have a smell, that Milne – inexplicably – could detect it, and that she could detect it long before diagnosis like she had with her husband, Les. But the experiments revealed other things that the team hadn't been expecting.
"One surprising thing we learned from that experiment was that the odor was always located in the back of the shirt – never in the armpit, where we expected the smell to be," Kunath says. "I had a chance meeting with a dermatologist and he said the smell was due to the patient's sebum, which are greasy secretions that are really dense on your upper back. We have sweat glands, instead of sebum, in our armpits." Patients with Parkinson's are also known to have increased sebum production.
With the knowledge that a patient's sebum was the source of the unusual smell, researchers could go on to investigate exactly what metabolites were in the sebum and in what amounts. Kunath, along with his associate, Dr. Perdita Barran, collected and analyzed sebum samples from 64 participants across the United Kingdom. Once the samples were collected, Barran and others analyzed it using a method called gas chromatography mass spectrometry, or GS-MC, which separated, weighed and helped identify the individual compounds present in each sebum sample.
Barran's team can now correctly identify Parkinson's in nine out of 10 patients – a much quicker and more accurate way to diagnose than what clinicians do now.
"The compounds we've identified in the sebum are not unique to people with Parkinson's, but they are differently expressed," says Barran, a professor of mass spectrometry at the University of Manchester. "So this test we're developing now is not a black-and-white, do-you-have-something kind of test, but rather how much of these compounds do you have compared to other people and other compounds." The team identified over a dozen compounds that were present in the sebum of Parkinson's patients in much larger amounts than the control group.
Using only the GC-MS and a sebum swab test, Barran's team can now correctly identify Parkinson's in nine out of 10 patients – a much quicker and more accurate way to diagnose than what clinicians do now.
"At the moment, a clinical diagnosis is based on the patient's physical symptoms," Barran says, and determining whether a patient has Parkinson's is often a long and drawn-out process of elimination. "Doctors might say that a group of symptoms looks like Parkinson's, but there are other reasons people might have those symptoms, and it might take another year before they're certain," Barran says. "Some of those symptoms are just signs of aging, and other symptoms like tremor are present in recovering alcoholics or people with other kinds of dementia." People under the age of 40 with Parkinson's symptoms, who present with stiff arms, are often misdiagnosed with carpal tunnel syndrome, she adds.
Additionally, by the time physical symptoms are present, Parkinson's patients have already lost a substantial amount of dopamine receptors – about sixty percent -- in the brain's basal ganglia. Getting a diagnosis before physical symptoms appear would mean earlier interventions that could prevent dopamine loss and preserve regular movement, Barran says.
"Early diagnosis is good if it means there's a chance of early intervention," says Barran. "It stops the process of dopamine loss, which means that motor symptoms potentially will not happen, or the onset of symptoms will be substantially delayed." Barran's team is in the processing of streamlining the sebum test so that definitive results will be ready in just two minutes.
"What we're doing right now will be a very inexpensive test, a rapid-screen test, and that will encourage people to self-sample and test at home," says Barran. In addition to diagnosing Parkinson's, she says, this test could also be potentially useful to determine if medications were at a therapeutic dose in people who have the disease, since the odor is strongest in people whose symptoms are least controlled by medication.
"When symptoms are under control, the odor is lower," Barran says. "Potentially this would allow patients and clinicians to see whether their symptoms are being managed properly with medication, or perhaps if they're being overmedicated." Hypothetically, patients could also use the test to determine if interventions like diet and exercise are effective at keeping Parkinson's controlled.
"We hope within the next two to five years we will have a test available."
Barran is now running another clinical trial – one that determines whether they can diagnose at an earlier stage and whether they can identify a difference in sebum samples between different forms of Parkinson's or diseases that have Parkinson's-like symptoms, such as Lewy Body Dementia.
"Within the next one to two years, we hope to be running a trial in the Manchester area for those people who do not have motor symptoms but are at risk for developing dementia due to symptoms like loss of smell and sleep difficulty," Barran had said in 2019. "If we can establish that, we can roll out a test that determines if you have Parkinson's or not with those first pre-motor symptoms, and then at what stage. We hope within the next two to five years we will have a test available."
In a 2022 study, published in the American Chemical Society, researchers used mass spectrometry to analyze sebum from skin swabs for the presence of the specific molecules. They found that some specific molecules are present only in people who have Parkinson’s. Now they hope that the same method can be used in regular diagnostic labs. The test, many years in the making, is inching its way to the clinic.
"We would likely first give this test to people who are at risk due to a genetic predisposition, or who are at risk based on prodomal symptoms, like people who suffer from a REM sleep disorder who have a 50 to 70 percent chance of developing Parkinson's within a ten year period," Barran says. "Those would be people who would benefit from early therapeutic intervention. For the normal population, it isn't beneficial at the moment to know until we have therapeutic interventions that can be useful."
Milne's husband, Les, passed away from complications of Parkinson's Disease in 2015. But thanks to him and the dedication of his wife, Joy, science may have found a way to someday prolong the lives of others with this devastating disease. Sometimes she can smell people who have Parkinson’s while in the supermarket or walking down the street but has been told by medical ethicists she cannot tell them, Milne said in an interview with the Guardian. But once the test becomes available in the clinics, it will do the job for her.
[Ed. Note: A older version of this hit article originally ran on September 3, 2019.]
Podcast: The Friday Five weekly roundup in health research
The Friday Five covers five stories in health research that you may have missed this week. There are plenty of controversies and troubling ethical issues in science – and we get into many of them in our online magazine – but this news roundup focuses on scientific creativity and progress to give you a therapeutic dose of inspiration headed into the weekend.
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Covered in this week's Friday Five:
- A new blood test for cancer
- Patches of bacteria can use your sweat to power electronic devices
- Researchers revive organs of dead pigs
- Phone apps detects cancer-causing chemicals in foods
- Stem cells generate "synthetic placentas" in mice
Plus, an honorable mention for early research involving vitamin K and Alzheimer's
Since the recent reversal of Roe v. Wade — the landmark decision establishing a constitutional right to abortion — the vulnerabilities of reproductive health data and various other information stored on digital devices or shared through the Web have risen to the forefront.
Menstrual period tracking apps are an example of how technologies that collect information from users could be weaponized against abortions seekers. The apps, which help tens of millions of users in the U.S. predict when they’re ovulating, may provide evidence that leads to criminal prosecution in states with abortion bans, says Anton T. Dahbura, executive director of the Johns Hopkins University Information Security Institute. In states where abortion is outlawed, “it’s probably best to not use a period tracker,” he says.
Following the Dobbs v. Jackson ruling in late June that overturned Roe, even women who suffered a miscarriage could be suspected of having an abortion in some cases. While using these apps in anonymous mode may appear more secure, “data is notoriously difficult to perfectly anonymize,” Dahbura says. “Whether the data are stored on the user’s device or in the cloud, there are ways to connect that data to the user.”
Completely concealing one’s tracks in cyberspace poses enormous challenges. Digital forensics can take advantage of technology such as GPS apps, security cameras, license plate trackers, credit card transactions and bank records to reconstruct a person’s activities,” Dahbura says. “Abortion service providers are also in a world of risk for similar reasons.”
Practicing “good cyber hygiene” is essential. That’s particularly true in states where private citizens may be rewarded for reporting on women they suspect of having an abortion, such as Texas, which passed a so-called bounty hunter law last fall. To help guard against hacking, Dahbura suggests using strong passwords and two-factor authentication when possible while remaining on alert for phishing scams on email or texts.
Another option for safeguarding privacy is to avoid such apps entirely, but that choice will depend on an individual’s analysis of the risks and benefits, says Leah Fowler, research assistant professor at the University of Houston Law Center, Health Law & Policy Institute.
“These apps are popular because people find them helpful and convenient, so I hesitate to tell anyone to get rid of something they like without more concrete evidence of its nefarious uses,” she says. “I also hate the idea that asking anyone capable of becoming pregnant to opt out of all or part of the digital economy could ever be a viable solution. That’s an enormous policy failure. We have to do better than that.”
The potential universe of abortion-relevant data can include information from a variety of fitness and other biometric trackers, text and social media chat records, call details, purchase histories and medical insurance records.
Instead, Fowler recommends that concerned consumers read the terms of service and privacy policies of the apps they’re using. If some of the terms are unclear, she suggests emailing customer service with questions until the answers are satisfactory. It’s also wise for consumers to research products that meet their specific needs and find out whether other women have raised concerns about specific apps. Users interested in more privacy may want to switch to an app that stores data locally, meaning the data stays on your device, or does not use third-party tracking, so the app-maker is the only company with access to it, she says.
Period tracking apps can be useful for those on fertility journeys, making it easier to store information digitally than on paper charts. But users may want to factor in whether they live in a state with an anti-abortion stance and run the risk of legal issues due to a potential data breach, says Carmel Shachar, executive director of the Petrie-Flom Center for Health Law Policy, Biotechnology, and Bioethics at Harvard Law School.
Consumers’ risks extend beyond period tracking apps in the post-Roe v. Wade era. “Anything that creates digital breadcrumbs to your reproductive choices and conduct could raise concerns — for example, googling ‘abortion providers near me’ or texting your best friend that you are pregnant but do not want to be,” Shachar says. Women also could incriminate themselves by bringing their phones, which may record geolocation data, to the clinic with them.
The potential universe of abortion-relevant data can include information from a variety of fitness and other biometric trackers, text and social media chat records, call details, purchase histories and medical insurance records, says Rebecca Wexler, faculty co-director of the Berkeley Center for Law & Technology. “These data sources can reveal a pregnant person’s decision to seek or obtain an abortion, as well as reveal a healthcare provider’s provision of abortion services and anyone else’s provision of abortion assistance,” she says.
In some situations, people or companies could inadvertently expose themselves to risk after posting on social media with offers of places for abortion seekers to stay after traveling from states with bans. They could be liable for aiding and abetting abortion. At this point, it’s unclear whether states that ban abortion will try to prosecute residents who seek abortions in other states without bans.
Another possibility is that a woman seeking an abortion will be prosecuted based not only on her phone’s data, but also on the data that law enforcement finds on someone else’s device or a shared computer. As a result, “people in one household may find themselves at odds with each other,” says K Royal, faculty fellow at the Center for Law, Science, and Innovation at Arizona State University’s Sandra Day O'Connor College of Law. “This is a very delicate situation.”
Individuals and corporate executives should research their options before leaving a digital footprint. “Guard your privacy carefully, whether you are seeking help or you are seeking to help someone,” Royal says. While she has come across recommendations from other experts who suggest carrying a second phone that is harder to link a person’s identity for certain online activities, “it’s not practical on a general basis.”
The privacy of this health data isn’t fully protected by the law because period trackers, texting services and other apps are not healthcare providers — and as a result, there’s no prohibition on sharing the information with a third party under the Health Insurance Portability and Accountability Act of 1996, says Florencia Marotta-Wurgler, a professor who specializes in online consumer contracts and data privacy at the NYU School of Law.
“So, as long as there is valid consent, then it’s fair game unless you say that it violates the reasonable expectations of consumers,” she says. “But this is pretty unchartered territory at the moment.”
As states implement laws granting anyone the power to report suspected or known pregnancies to law enforcement, anti-choice activists are purchasing reproductive health data from companies that make period apps, says Rebecca Herold, chief executive officer of Privacy & Security Brainiacs in Des Moines, Iowa, and a member of the Emerging Trends Working Group at ISACA, an association focused on information technology governance. They could also buy data on search histories and make it available in places like Texas for “bounty hunters” to find out which women have searched for information about abortions.
Some groups are creating their own apps described as providing general medical information on subjects such as pregnancy health. But they are “ultimately intended to ‘catch’ women” — to identify those who are probably pregnant and dissuade them from having an abortion, to launch harassment campaigns against them, or to report them to law enforcement, anti-choice groups and others in states where such prenatal medical care procedures are now restricted or prohibited, Herold says.
In addition to privacy concerns, the reversal of Roe v. Wade raises censorship issues. Facebook and Instagram have started to remove or flag content, particularly as it relates to providing the abortion pill, says Michael Kleinman, director of the Silicon Valley Initiative at Amnesty International USA, a global organization that promotes human rights.
Facebook and Instagram have rules that forbid private citizens from buying, selling or giving away pharmaceuticals, including the abortion pill, according to a social media post by a communications director for Meta, which owns both platforms. In the same post, though, the Meta official noted that the company’s enforcement of this rule has been “incorrect” in some cases.
“It’s terrifying to think that arbitrary decisions by these platforms can dramatically limit the ability of people to access critical reproductive rights information,” Kleinman says. However, he adds, “as it currently stands, the platforms make unilateral decisions about what reproductive rights information they allow and what information they take down.”