Medication use is associated with cognitive deficits in people with multiple sclerosis

<h3>Background</h3> People with multiple sclerosis (pwMS) receive medications with anticholinergic and sedative effects that may contribute to cognitive decline. We studied the effect of these medications and polypharmacy on cognitive deficit among pwMS. <h3>Methods</h3> This retrospective cross-sectional study of an MS referral centre included pwMS who attended clinic between 1/11/2022 and 31/10/2023 (n=486). The Drug Burden Index (DBI) and Anticholinergic Effect on Cognition (AEC) scales assessed the cognitive burden of their medications. Polypharmacy was defined as taking ≥5 medications. The Symbol Substitution Task (SST) and Perceived Deficit Questionnaire-5 (PDQ-5) assessed objective and subjective cognitive deficits, respectively. The association of DBI, AEC, and polypharmacy with these tests was analysed using multivariable regression analysis. <h3>Results</h3> Raised DBI and AEC are associated with lower SST scores (unstandardised B= -1.6, (95%CI -2.6, -0.5) and B= -0.8, (-1.4, -0.3) respectively). DBI and AEC are positively associated with PDQ-5 (B= 0.8 (0.4, 1.2) and B= 0.3 (0.1, 0.5)). Polypharmacy is similarly associated with a lower SST (B = -2.3 (-4.4, -0.1)) and a higher PDQ-5 (B = 1.1 (0.2, 1.9)). <h3>Conclusion</h3> Anticholinergic and sedative medications and polypharmacy negatively affect cognition in pwMS. These medications must be prescribed cautiously. Further studies on deprescribing these medications are needed.