Measuring depression with wearables

Depression and emotional disorders can occur at any time of year — and do for millions of Americans. But feeling sad, lonely, anxious and depressed may seem particularly isolating during this holiday season, which is supposed to be a time of joy and celebration.

A team of Stanford researchers believes that one way to work towards ameliorating this suffering is to develop a better way to quantitatively measure stress, anxiety and depression.

“One of the biggest barriers for psychiatry in the field that I work in is that we don’t have objective tests. So the way that we assess mental health conditions and risks for them is by interview and asking you how do you feel,” said Leanne Williams, MD, a professor in psychiatry and behavioral sciences at Stanford, when she spoke at a Stanford Reunion Homecoming alumni celebration.

She added, “Imagine if you were diagnosing and treating diabetes without tests, without sensors. It’s really impossible to imagine, yet that is what we’re doing for mental health, right now.”

Instead, Stanford researchers want to collect and analyze data from wearable devices to quantitatively characterize mental states. The multidisciplinary team includes scientists from the departments of psychiatry, chemical engineering, bioengineering, computer science and global health.

Their first step was to use functional magnetic resonance imaging to map the brain activity of healthy controls compared to people with major depressive disorder who were imaged before and after they were treated with antidepressants.

The researchers identified six “biotypes” of depression, representing different ways brain circuitry can be disrupted to cause specific symptoms. They classified the biotypes as rumination, anxious avoidance, threat dysregulation, anhedonia, cognitive dyscontrol and inattention.

“For example, threat dysregulation is when the brain stays in alarm mode after acute stress and you feel heart racing, palpitations, sometimes panic attacks,” presented Williams, “and that’s the brain not switching off from that mode,” Williams said.

The team, which includes chemical engineer Zhenan Bao, PhD, then identified links between these different brain biotypes and various physiological differences, including changes in heart rate, skin conductance, electrolyte levels and hormone production. In particular, they found correlations between the biotypes and production of cortisol, a hormone strongly related to stress level.

Now, they are developing a wearable device — called MENTAID — that measures the physiological parameters continuously. Their current prototype can already measure cortisol levels in sweat in agreement with standard laboratory measurements. This was an incredibly challenging task due to the extremely low concentration and tiny molecular size of cortisol.

Going forward, they plan to validate their wearable device with clinical trials, including studies to assess its design and user interface. Ultimately, the researchers hope MENTAID will help prevent and treat mental illness — for example, by better predicting and evaluating patient response to specific anti-depressants.

Photo by Sora Sagano

This is a reposting of my Scope blog story, courtesy of Stanford School of Medicine.

Wearable device designed to measure cortisol in sweat

Photo by Brodie Vissers

Scientists are sweating over how to measure perspiration. That’s because sweat provides a lot of information about a person’s health status, since it contains important electrolytes, proteins, hormones and other factors.

Now, Stanford researchers have developed a wearable device to measure how much cortisol people produce in their sweat.

Cortisol is a hormone critical for many processes in the body, including blood pressure, metabolism, inflammation, memory formation and emotional stress. Too much cortisol over a prolonged period of time can lead to chronic diseases, such as Cushing syndrome.

“We are particularly interested in sweat sensing, because it offers noninvasive and continuous monitoring of various biomarkers for a range of physiological conditions,” said Onur Parlak, PhD, a Stanford postdoctoral research fellow in materials science and engineering, in a recent news release. “This offers a novel approach for the early detection of various diseases and evaluation of sports performance.”

Currently, cortisol levels are usually measured with a blood test that takes several days to analyze in the lab. So Stanford material scientists developed a wearable sensor — a stretchy patch placed on the skin. After the patch soaks up sweat, the user attaches it to a device for analysis and gets the cortisol level measurements in seconds.

As recently reported in Science Advances, the new wearable sensor is composed of four layers of materials. The bottom layer next to the skin passively wicks in sweat through an array of channels, and then the sweat collects in the reservoir layer. Sitting on top of the reservoir is the critical component, a specialized membrane that specifically binds to cortisol. Charged ions in the sweat, like sodium or potassium, pass through the membrane unless the bound cortisol blocks them — and those charged ions are detected by the analysis device, rather than directly measuring the cortisol. Finally, the top waterproof layer protects the sensor from contamination.

The Stanford researchers did a series of validation tests in the lab, and then they strapped the device onto the forearms of two volunteers after they went for a 20-minute outdoor run. Their device’s lab and real-world results were comparable to the corresponding cortisol measurements made with a standard analytic biochemistry assay.

Before this prototype becomes available, however, more research is needed. The research team plans to integrate the wearable patch with the analysis device, while also making it more robust when saturated with sweat so it’s reusable. They also hope to generalize the design to measure several biomarkers at once, not just cortisol.

This is a reposting of my Scope blog story, courtesy of Stanford School of Medicine.