A New Smartphone-Based Cognitive Screening Battery for Multiple Sclerosis (icognition): Validation Study - Stijn Denissen; Delphine Van Laethem; Johan Baijot; Lars Costers; Annabel Descamps; Ann Van Remoortel; Annick Van Merhaegen-Wieleman; Marie D’hooghe; Miguel D'Haeseleer; Dirk Smeets; Diana M Sima; Jeroen Van Schependom; et al. (Journal of Medical Internet Research)