https://doi.org/10.1177/1352458519891984 https://doi.org/10.1177/1352458519891984 MULTIPLE SCLEROSIS MSJ JOURNAL journals.sagepub.com/home/msj 1 Multiple Sclerosis Journal 1–10 DOI: 10.1177/ 1352458519891984 © The Author(s), 2019. Article reuse guidelines: sagepub.com/journals- permissions Introduction/background Multiple sclerosis (MS) is a chronic and progressive central nervous system (CNS) disorder characterized by demyelination, immune-mediated inflammation, and neurodegeneration. Pediatric-onset multiple scle- rosis (POMS) occurs in approximately 3% of MS cases and is considered a rare disorder of childhood. 1 As such, less is known about this MS subgroup and how the disease may affect ongoing neurodevelopment. Cognitive impairment occurs in up to 65% of all adults with MS 2 and is estimated to occur in approximately one-third of POMS cases. 3–7 The long-term conse- quences for these children remain unclear; however, adults with pediatric- relative to adult-onset MS have worse cognitive performance. 8,9 Routine cognitive screening is now recommended for all MS patients 10 and is particularly important for those in the pediatric age group with MS as they could be at greatest risk of cognitive involvement and related complications. Cognitive screening early in the disease course is important since the identification of problems and prompt intervention could hopefully lead to better Cognitive processing speed in pediatric-onset multiple sclerosis: Baseline characteristics of impairment and prediction of decline Asya I Wallach , Michael Waltz, T Charles Casper, Gregory Aaen, Anita Belman, Leslie Benson, Tanuja Chitnis , Mark Gorman, Jennifer Graves , Yolanda Harris, Timothy E Lotze, Soe Mar, Manikum Moodley, Jayne M Ness, Mary Rensel, Moses Rodriguez, John W Rose, Teri Schreiner, Jan-Mendelt Tillema, Emmanuelle Waubant, Bianca Weinstock-Guttman, Leigh E Charvet and Lauren B Krupp; on behalf of the US Network of Pediatric Multiple Sclerosis Centers Abstract Background: Cognitive impairment occurs in approximately one-third of pediatric-onset multiple scle- rosis (POMS) patients. The Symbol Digit Modalities Test (SDMT), a widely used cognitive screen in adults, has yet to be incorporated early into the standard care of POMS. Objective: To screen for cognitive impairment early in the course of POMS and analyze predictive fac- tors. Methods: Of the 955 POMS or clinically isolated syndrome (CIS) patients prospectively assessed from March 2014 to July 2018, 500 POMS and 116 CIS patients met inclusion criteria (disease onset before the age of 18, one or more SDMTs, and 8 years or older at the time of testing). Those with relapse were analyzed separately from those who were relapse-free. Results: At initial assessment, the mean (interquartile range (IQR)) age at symptom onset was 13.5 years (12.0, 15.9) and the mean (±SD) disease duration was 3.0 ± 2.9 years. Impaired processing speed occurred in 23.4% of POMS and in 16.4% of CIS. On serial testing (n = 383, mean follow-up: 1.8 years), 14.1% had clinically meaningful decline predicted by older age of multiple sclerosis (MS) onset and male gender. Disease relapse or steroid use led to transient worsening on the SDMT. Conclusion: Early in the disease, some POMS and CIS patients are at risk for cognitive impairment and subsequent decline. Keywords: Pediatric-onset multiple sclerosis, pediatric MS, symbol digit modalities test, cognition, cognitive processing speed, multiple sclerosis Date received: 16 July 2019; revised: 7 October 2019; accepted: 23 October 2019. Correspondence to: LB Krupp Pediatric Multiple Sclerosis Center, Department of Neurology, NYU Langone Medical Center, 222 East 41st Street, 10th Floor, New York, NY 10017, USA. Lauren.Krupp@ nyulangone.org; Twitter: @AsenkaMD Asya I Wallach Anita Belman Leigh E Charvet Lauren B Krupp Pediatric Multiple Sclerosis Center, Department of Neurology, NYU Langone Medical Center, New York, NY, USA Michael Waltz T Charles Casper John W Rose Pediatrics, The University of Utah, Salt Lake City, UT, USA Gregory Aaen Pediatric Multiple Sclerosis Center, Loma Linda University, Loma Linda, CA, USA Leslie Benson Tanuja Chitnis Partners Multiple Sclerosis Center, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA Mark Gorman Boston Children’s Hospital, Boston, MA, USA Jennifer Graves Pediatric MS Center, Neurology, University of California, San Diego, San Diego, CA, USA Yolanda Harris Jayne M Ness Center for Pediatric-Onset Demyelinating Disease, Children’s of Alabama, University of Alabama at Birmingham, Birmingham, 891984MSJ 0 0 10.1177/1352458519891984Multiple Sclerosis JournalAI Wallach, M Waltz research-article2019 2019 Original Research Paper