That leaves methods that are invasive, like spinal taps, or expensive, like PET scans. These approaches can’t be used to screen large groups of people. “They’re not available everywhere,” Ms. Bayat said. “They’re not very accessible or scalable.”
But a GPS device in someone’s car could monitor driving behavior almost continuously at low cost, providing so-called digital biomarkers. “Studies have shown that driving changes in people with symptomatic Alzheimer’s,” Ms. Bayat said. “But some changes occur even earlier.”
The Washington University study enrolled 64 older adults with preclinical Alzheimer’s, as determined by spinal taps (the results were not shared with participants), and 75 who were deemed cognitively normal.
For a year, researchers measured both groups’ driving performance — how often they accelerated or braked aggressively, exceeded or fell well below the speed limit, made abrupt moves — and their “driving space” (number of trips, average distance, unique destinations, trips at night). “Only now, because we have these technologies, can we do this kind of research,” Ms. Bayat said.
The study found that driving behavior and age could predict preclinical Alzheimer’s 88 percent of the time. Those findings could spur recruitment for clinical trials and allow interventions — like an alert when a car drifts — to help keep drivers on the road. In areas with inadequate public transportation (which is most areas), that could enhance seniors’ independence.
Dr. Jason Karlawish, a geriatrician and co-director of the Penn Memory Center, called the study “provocative” and well designed. “The results suggest that monitoring a real-world, cognitively intense behavior can detect the earliest, subtle signs of emerging cognitive impairment,” he said in an email.
Similarly, a study analyzing medical records and consumer credit reports for more than 80,000 Medicare beneficiaries showed that seniors who eventually received a diagnosis of Alzheimer’s disease were significantly more likely to have delinquent credit card payments than those who were demographically similar but never received such diagnoses. They also were more likely to have subprime credit scores.