In-ear microphones could help doctors ‘listen’ for early signs of Alzheimer’s

ISLAMABAD, JAN 04 (ONLINE): Currently, there is no single test to help detect Alzheimer’s disease, a type of dementia that is characterized by memory loss, confusion, communication issues, and mood changes.
Doctors can use cognitive tests, cerebrospinal fluid, and blood tests combined with brain scans to look for changes in the brain to diagnose Alzheimer’s
Scientists are now investigating using earpiece microphones, also known as hearables, to detect early signs of Alzheimer’s as a noninvasive test.
The researchers behind this believe hearables could also help diagnose other neurodegenerative diseases like Parkinson’s early.
There is no known cure for Alzheimer’s disease, and early diagnosis remains a challenge.

In recent years, scientists have been trying to develop blood tests to help diagnose neurodegenerative diseases like Alzheimer’s disease sooner. AI scans have also helped detect signs of change in the brain earlier.

Now, researchers are looking at a different avenue: the ears. They aim to spot signs of cognitive impairment early by recording sounds and vibrations in the eardrums.

Researchers from the École de Technologie Supérieure in Montreal, Canada, and Geisel School of Medicine at Dartmouth in Hanover, NH, are exploring using earpiece microphones to detect early signs of Alzheimer’s.

Miriam Boutros, a Master’s of Science student at at the École de Technologie Supérieure, presented the team’s work, “Towards the Detection of Alzheimer’s Disease through Eye Movement Changes Using a Hearable,” on November 19, 2024, at the virtual 187th Meeting of the Acoustical Society of America.

The team is now recruiting participants with Alzheimer’s disease and mild cognitive impairment for the study.

Their research is yet to be published in a peer-reviewed journal.

“In the journey to improve healthcare, early disease detection is critical to prevent, delay, or mitigate the symptoms of the disease. At the forefront of this effort is advanced intra-aural technology, or what we call hearables. These small yet powerful wearable devices, positioned within the ear canal, serve as a gateway to a vast array of signals produced by the human body.”
— Miriam Boutros, researcher, speaking to media at a press conference

How the ears can hold clues to Alzheimer’s
People with Alzheimer’s often experience impaired motor control, such as apraxia and gait disturbances. Changes in saccades or involuntary rapid eye movements that shift the eye from one target to another are also signs of cognitive decline.

The neurodegeneration associated with Alzheimer’s often leads to slower eye movements and more mistakes when performing eye-tracking tasks.

As these saccades happen, they cause vibrations in the eardrums. This is where these sensitive in-ear microphones come into play. By analyzing these vibrations, the researchers want to develop algorithms that will help them differentiate physiological signals that may indicate neurological disorders like Alzheimer’s.

“Alzheimer’s disease patients have saccades that are shorter, more variable and less accurate. Also, eye movements cause vibrations of the eardrum, which can be detected by the in-ear microphones of the hearables. This means that hearables are a good potential method to track eye movement changes,” explained Boutros.

She said that the in-ear microphone would be inserted into the ear canal to collect multiple signals.

“We can actually see the heartbeat, we can see the breathing, and then [w]e can actually see eye movement,” she noted.

For this, the researchers will conduct experiments with participants and compare the data they receive from them wearing the hearables and conventional eye movement trackers. They will try to correlate oscillations in the eardrums with the amplitude and trajectory of saccades.

“Containing in-ear microphones, hearables capture signals with remarkable sensitivity. In fact, when the ear canal is occluded, vibrations generated by bone and tissue conduction become amplified. This means that subtle sounds from the wearer’s heartbeat to their voice, cough, breath, or even the blink of an eye can be detected.”
— Miriam Boutros

The study involves experiments with volunteers wearing both wearables and conventional eye trackers to correlate eardrum oscillations with the amplitude and trajectory of saccades. Compared to traditional eye movement trackers, which can lack accuracy and precision, wearables are a more ubiquitous and less intrusive technology.

The researchers’ long-term goal is to create a noninvasive, wearable device that can continuously monitor for Alzheimer’s and potentially other neurological diseases, which would help scientists detect signs earlier than the standard diagnosis timeframe.

Challenges ahead
Medical News Today spoke to Alexander Solomon, MD, surgical neuro-ophthalmologist and strabismus surgeon at Pacific Neuroscience Institute at Providence Saint John’s Health Center in Santa Monica, CA, who was not involved in the research, about the potential of these hearables.

“I think it’s an interesting premise, but I worry about the number of variables that could interfere with their data and limit real-world utility,” Solomon said.

When asked about what challenges the researchers should anticipate when using both the eye-tracking device and the hearable device simultaneously, Solomon said many things could limit their data and applicability.

“[Many things] ranging from alternative diagnoses affecting eye movements to the amount of signal-to-noise ratio would limit the utility of such a device in the real world, partially because you are inferring eye movement from changes in the oscillations rather than tracking it directly. While a wearable is convenient for gathering data without intruding on a patient population, there are many more accurate ways to assess eye movements relatively quickly and accurately in a clinic environment,” he explained.

Nonetheless, the proposal of such technology is promising for the future detection and diagnosis of Alzheimer’s.

“Anything we can do to detect the disease earlier is a boon for making sure patients are caught early on in the disease course — as treatments are developed and improve catching the disease before there are more permanent changes in cognition will likely be key. [W]hile I have questions about this particular wearable, methods of screening patients in spaces they’re already in will be very helpful in doing so,” Solomon told MNT.

Using in-ear microphones to spot signs of Parkinson’s
Tracking symptoms through in-ear signals may also bring about the possibility of detecting and differentiating between other neurological diseases. One particular disease, according to Boutros and her team, is Parkinson’s disease.

“[S]o, eventually we’re aiming to tackle more than just Alzheimer’s. We’re actually also looking into Parkinson’s. We have another colleague that’s working on Parkinson’s disease, but all the work is at the starting phase, so we’re still now making a proof of concept,” Boutros said.

She said that eventually when they create the device that can also be personalized to the person who’s wearing it, it will enable them to find differences between the biosignals now and past, possibly leading to an early diagnosis.

Boutros said that her colleagues would focus on swallow detection to detect signs of Parkinson’s disease because “Parkinson’s disease patients have difficulties swallowing and regulating their breath. [S]wallowing is very visible when we get the signal from the in-ear microphone.”