If your alertness and reaction speed fluctuate more than usual, you may be more susceptible to a viral illness. The study was led by experts from the University of Michigan who worked closely with colleagues from Duke University School of Medicine and the University of Virginia.
Alfred Hero, professor of electrical engineering and computer science at John H. Holland Distinguished University. and corresponding author of the study in Scientific Reports said “We all know that if we’re stressed or haven’t had enough sleep, it predisposes us to have a less resilient immune system. This is the first human exposure study to show that a person’s cognitive performance before exposure to a respiratory virus can predict the severity of infection”.
Subtle changes in day-to-day cognitive performance can signal changes in brain states known to increase the risk of disease, such as stress, fatigue and poor sleep. The team wanted to measure cognitive function and investigate whether this predicted immune performance after exposure to a respiratory virus. Cognitive variability measured by a home digital self-test has been shown to be highly predictive.
The team studied a cohort of 18 healthy volunteers who underwent brain performance tests three times a day for three days and were then exposed to a common cold virus known as human rhinovirus. The software provided 18 measures of cognitive function including reaction time, attention, and rapid switching between numbers and symbols, which were combined to derive an index of variability.
Yaya Zhai, a recent U-M bioinformatics Ph.D. graduate and the study’s first author says “At the beginning, we didn’t find that cognitive function had a significant association with disease susceptibility because we used a raw score. But later, when we looked at changes over time, we found that variation in cognitive function is closely related to immunity and susceptibility”.
The team assessed viral shedding by using saline to flush the participants’ nasal passages. They determined the presence of viral infection and the amount of virus in the fluid by growing the virus in cell culture. For symptoms, the team used the Jackson Score, in which participants rate themselves from one to three out of eight common cold symptoms.
Ronald Turner, professor emeritus of pediatrics at the University of Virginia, who led the experiment says “his is an interesting observation in a relatively small study. I hope there will be a chance to confirm these findings in a larger”.
The team is optimistic that using a smartphone could eventually help identify times of increased susceptibility to disease, monitor cognitive indicators such as typing speed and accuracy, as well as how much time the user spends sleeping.
P. Murali Doraiswamy, director of the Neurocognitive Disorders Program at Duke University School of Medicine, who designed the neurocognitive testing portion of the study says “Traditional clinical cognitive assessments, which look at raw scores at a single time point, often do not provide a true picture of brain health”.
The study was part of a project funded by the Defense Advanced Research Projects Agency to see if it was possible to predict soldiers’ susceptibility to disease. That project was led by Geoffrey Ginsburg, then a professor at the Duke Center for Applied Genomics and Precision Medicine, and led a contingent of the team analyzing blood samples for biomarkers that might indicate susceptibility to disease. The experiment also discovered several genetic markers that may indicate reduced immune function, which the team can further explore in future studies.