A New Smartphone-Based Cognitive Screening Battery for Multiple Sclerosis (icognition): Validation Study
Authors: Denissen Stijn , Van Laethem Delphine , Baijot Johan , Costers Lars , Descamps Annabel , Van Remoortel Ann , Van Merhaegen-Wieleman Annick , D’hooghe Marie , D'Haeseleer Miguel , Smeets Dirk , Sima Diana M , Van Schependom Jeroen , Nagels Guy 
Published: January 2025

Background
Cognitive deterioration is common in multiple sclerosis (MS) and requires regular follow-up. Currently, cognitive status is measured in clinical practice using paper-and-pencil tests, which are both time-consuming and costly. Remote monitoring of cognitive status could offer a solution because previous studies on telemedicine tools have proved its feasibility and acceptance among people with MS. However, existing smartphone-based apps include designs that are prone to motor interference and focus primarily on information processing speed, although memory is also commonly affected.

Objective
This study aims to validate a smartphone-based cognitive screening battery, icognition, to detect deterioration in both memory and information processing speed.

Methods
The icognition screening battery consists of 3 tests: the Symbol Test for information processing speed, the Dot Test for visuospatial short-term memory and learning, and the visual Backward Digit Span (vBDS) for working memory. These tests are based on validated paper-and-pencil tests: the Symbol Digit Modalities Test, the 10/36 Spatial Recall Test, and the auditory Backward Digit Span, respectively. To establish the validity of icognition, 101 people with MS and 82 healthy participants completed all tests. Of the 82 healthy participants, 20 (24%) repeated testing 2 to 3 weeks later. For each icognition test, validity was established by the correlation with its paper-and-pencil equivalent (concurrent validity), the correlation and intraclass correlation coefficient (ICC) between baseline and follow-up testing (test-retest reliability), the difference between people with MS and healthy participants, and the correlation with other clinical parameters such as the Expanded Disability Status Scale.

Results
All icognition tests correlated well with their paper-and-pencil equivalents (Symbol Test: r=0.67; P<.001; Dot Test: r=0.31; P=.002; vBDS: r=0.69; P<.001), negatively correlated with the Expanded Disability Status Scale (Symbol Test: ρ=–0.34; P<.001; Dot Test: ρ=−0.32; P=.003; vBDS: ρ=−0.21; P=.04), and showed moderate test-retest reliability (Symbol Test: ICC=0.74; r=0.85; P<.001; Dot Test: ICC=0.71; r=0.74; P<.001; vBDS: ICC=0.72; r=0.83; P<.001). Test performance was comparable between people with MS and healthy participants for all cognitive tests, both in icognition (Symbol Test: U=4431; P=.42; Dot Test: U=3516; P=.32; vBDS: U=3708; P=.27) and the gold standard paper-and-pencil tests (Symbol Digit Modalities Test: U=4060.5, P=.82; 10/36 Spatial Recall Test: U=3934; P=.74; auditory Backward Digit Span: U=3824.5, P=.37).

Conclusions
icognition is a valid tool to remotely screen cognitive performance in people with MS. It is planned to be included in a digital health platform that includes volumetric brain analysis and patient-reported outcome measures. Future research should establish the usability and psychometric properties of icognition in a remote setting.