Digital biomarkers can highlight subtle clinical differences in radiologically isolated syndrome compared to healthy controls.

Objective To explore the use of digital biomarkers to distinguish healthy controls (HC) from subjects with a radiologically isolated syndrome (RIS). Methods We developed a smartphone application called MS Screen Test (MSST) to explore several dimensions of the neurological exam such as finger tapping speed, agility, hand synchronization, low contrast vision and cognition during a short evaluation. This app was tested on a cohort of healthy volunteers including a subset of subjects who underwent two evaluations on the same day to assess reproducibility. In a second step, the app was tested on a cohort of RIS subjects. Performances of RIS subjects were compared with age and genre-matched HC. Results HC underwent two consecutive evaluations on MSST. The analysis showed good reproducibility for all measures. Then 21 RIS subjects were compared to 32 matched HC. Compared to HC, we found that RIS subjects had a lower finger tapping speed on the dominant hand (5.6 versus 6.5 taps per second; p = 0.005), a longer inter hand interval during the hand synchronization task (14.4 versus 11.3 ms; p = 0.03) and significantly poorer scores on the low contrast vision and cognition tests. Conclusion MSST only requires a smartphone to obtain digital biomarkers relative to several dimensions of the neurological examination. Our results highlighted subtle differences between HC and RIS subjects. We plan to evaluate this tool in MS patients, which will allow us to get a much larger sample of subjects, to determine whether digital biomarkers can predict disease course.