How stressed are you? Your earwax could hold the answer.
A new method of collecting and analyzing earwax for levels of the stress hormone cortisol may be a simple and cheap way to track the mental health of people with depression and anxiety.
Cortisol is a crucial hormone that spikes when a person is stressed and declines when they're relaxed. In the short-term, the hormone is responsible for the "fight or flight" response, so it's important for survival. But cortisol is often consistently elevated in people with depression and anxiety, and persistent high levels of cortisol can have negative effects on the immune system, blood pressure and other bodily functions.
There are other disorders which involve abnormal cortisol, including Cushing's disease (caused by the overproduction of cortisol) and Addison's disease (caused by the underproduction of cortisol). People with Cushing's disease have abnormal fat deposits, weakened immune systems and brittle bones. People with Addison's disease have dangerously low blood pressure.
Tracking cortisol levels
There are a lot of ways to measure cortisol: in saliva, in blood, even in hair. But saliva and blood samples capture only a moment in time, and cortisol fluctuates significantly throughout the day. Even the experience of getting a needle stick to draw blood can increase stress, and thus cortisol levels. Hair samples can provide a snapshot of cortisol over several months instead of several minutes, but hair can be expensive to analyze — and some people don't have much of it.
Andrés Herane-Vives, a lecturer at University College London's Institute of Cognitive Neuroscience and Institute of Psychiatry, and his colleagues instead turned to the ear. Earwax is stable and resistant to bacterial contamination, so it can be shipped to a laboratory easily for analysis. It also can hold a record of cortisol levels stretching over weeks.
But previous methods of harvesting earwax involved sticking a syringe into the ear and flushing it out with water, which can be slightly painful and stressful. So Herane-Vives and his colleagues developed a swab that, when used, would be no more stressful than a Q-tip. The swab has a shield around the handle, so that people can't stick it too far into their ear and damage their eardrum, and a sponge at the end to collect the wax.
In a small pilot study, researchers collected blood, hair and earwax from 37 participants at two different time points. At each collection point, they sampled earwax using a syringe from one ear, and using the new self-swab method from the other. The researchers then compared the reliability of the cortisol measurements from the self-swab earwax with that of the other methods.
They found that cortisol was more concentrated in earwax than in hair, making for easier analysis. Analyzing the self-swabbed earwax was also faster and more efficient than analyzing the earwax from the syringe, which had to be dried out before using. Finally, the earwax showed more consistency in cortisol levels compared with the other methods, which were more sensitive to fluctuations caused by things like recent alcohol consumption. Participants also said that self-swabbing was more comfortable than the syringe method.
The researchers reported their findings Nov. 2 in the journal Heliyon. Herane-Vives is also starting a company called Trears to market the new method. In the future, he hopes that earwax could also be used to monitor other hormones. The researchers also need to follow up with studies of Asian individuals, who were left out of this pilot study because a significant number only produce dry, flaky earwax as opposed to wet, waxy earwax.
"After this successful pilot study, if our device holds up to further scrutiny in larger trials, we hope to transform diagnostics and care for millions of people with depression or cortisol-related conditions such as Addison's disease and Cushing syndrome, and potentially numerous other conditions," he said in a statement.
Originally published in Live Science.
Live Science newsletter
Stay up to date on the latest science news by signing up for our Essentials newsletter.
Stephanie Pappas is a contributing writer for Live Science, covering topics ranging from geoscience to archaeology to the human brain and behavior. She was previously a senior writer for Live Science but is now a freelancer based in Denver, Colorado, and regularly contributes to Scientific American and The Monitor, the monthly magazine of the American Psychological Association. Stephanie received a bachelor's degree in psychology from the University of South Carolina and a graduate certificate in science communication from the University of California, Santa Cruz.