‘Catchy’ smartphone app could make it easier to screen for neurological conditions at home

Researchers at the University of California, San Diego have developed a smartphone app that could help people screen for Alzheimer’s disease, ADHD and other neurological diseases and disorders – by recording close-ups of their eye.

The app uses a near-infrared camera, built into newer smartphones for facial recognition, as well as a standard selfie camera to track changes in a person’s pupil size. These pupil measurements could be used to assess a person’s cognitive state.

The technology is described in a paper that will be presented at the ACM Computer Human Interaction Conference on Human Factors in Computing Systems (CHI 2022), taking place April 30-May 5 in New Orleans as an event hybrid on site.

“While there is still a lot of work to be done, I am excited about the potential for using this technology to take neurological screening out of clinical labs and into the home,” said Colin Barry, licensee of a doctorate in electrical and computer engineering. student at UC San Diego and first author of the paper, which received an honorable mention for the best paper award. “We hope this will open the door to further explorations of using smartphones to detect and monitor potential health issues earlier.”

Pupil size can provide information about a person’s neurological functions, according to recent research. For example, pupil size increases when a person performs a difficult cognitive task or hears an unexpected sound.

Measuring changes in pupil diameter is done by doing what is called a pupil response test. The test could offer a simple and easy way to diagnose and monitor various neurological diseases and disorders. However, it currently requires specialized and expensive equipment, which makes it impractical to perform outside of the laboratory or clinic.

Engineers from the Digital Health Lab, led by UC San Diego Professor of Electrical and Computer Engineering Edward Wang, collaborated with researchers from the UC San Diego Mental Health Technology Center (MHTech Center) to develop a more affordable and accessible solution.

“A scalable smartphone-based assessment tool that can be used for large-scale community screenings could facilitate the development of student response tests as minimally invasive and inexpensive tests to aid in the detection and understanding of diseases like Alzheimer’s disease. This could have a huge public health impact,” said Eric Granholm, professor of psychiatry at UC San Diego School of Medicine and director of the MHTech Center.

The app developed by the UC San Diego team uses a smartphone’s near-infrared camera to detect a person’s pupil. In the near infrared spectrum, the pupil can be easily differentiated from the iris, even in eyes with darker iris colors. This allows the app to calculate pupil size with sub-millimeter accuracy on different eye colors. The app also uses a color image taken by the smartphone’s selfie camera to capture the stereoscopic distance between the smartphone and the user. The app then uses this distance to convert the pupil size of the near-infrared image into millimeter units.

The app’s measurements were comparable to those taken by a device called a pupillometer, which is the gold standard for measuring pupil size.

The researchers also included various features in their app to make it more senior-friendly.

“For us, one of the most important factors in technology development is to ensure that these solutions are ultimately usable by everyone. This includes people like the elderly who might not be used to using smartphones. “, said Barry.

Researchers worked with older adult participants to design a simple app interface that allows users to self-administer student response tests. This interface included voice commands, image-based instructions, and a cheap plastic bezel to instruct the user to place their eye within view of the smartphone camera.

“By testing directly with seniors, we’ve discovered ways to improve the overall usability of our system and have even helped innovate senior-specific solutions that allow people with different physical limitations to use our system. successfully,” said Wang, who is also a faculty member at the UC San Diego Design Lab. “When developing technologies, we need to look beyond function as the sole measure of success, to understanding how our solutions will be used by a wide variety of end users.”

The Digital Health Lab is continuing this work as part of a project to enable a similar pupillometry feature on any smartphone rather than newer smartphones. Future studies will also involve working with older adults to assess home use of technology. The team will work with older adults with mild cognitive impairment to test the app as an early-stage Alzheimer’s risk screening tool.

This work was funded by the National Institute on Aging.

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