The Impact of Cladribine Tablets on Cognition Over One Year in Patients With Multiple Sclerosis: A Preliminary Study

INTRODUCTION: Cognitive impairment is common in multiple sclerosis (MS), affecting >40% of patients. Cladribine tablets are a high-efficacy MS disease-modifying therapy to prevent relapses and limit disease progression. Our previous study showed cortical gray matter lesion stability over one year after the start of cladribine, though its effect on cognition is not well known. This study aimed to investigate the one-year impact of cladribine tablets on cognition in multiple sclerosis. METHODS: Fourteen MS subjects [age (mean ± SD) 50.2 ± 10.8, 7.14% men, 57.1% relapsing-remitting MS (n = 8), 42.9% secondary progressive (n = 6), expanded disability status scale 4.1 ± 2.1] were administered the Brief Repeatable Battery of Neuropsychological Tests (BRB-N) and the Stroop Color and Word Test (Stroop) at an average of 1.5 months from cladribine start. The BRB-N measures information processing speed (Symbol Digit Modalities Test, Paced Auditory Serial Addition Test [PASAT]), verbal memory (Selective Reminding Test [SRT]), visual-spatial memory (10/36 Spatial Recall Test), and verbal fluency (Word List Generation). Stroop assesses processing speed and executive function. When available, alternate versions of the individual cognitive tests were used at follow-up to reduce practice effects. Paired t-tests compared within-subject baseline and follow-up data. RESULTS: After one year, no worsening was noted on any cognitive test. Furthermore, both PASAT 3-second total correct and SRT total delayed recall trended toward improved scores on-study, with an average 3.4 (p = 0.07) and 1.1 (p = 0.05) point increase, respectively. CONCLUSION: In this preliminary study, no clear decline in cognitive performance was detectable over one year in patients newly started on cladribine tablets.