Prevalence and Odds of Cognitive Impairment in Multiple Sclerosis Subtypes and Neuromyelitis Optica Spectrum Disorder: A Case-Control Study.

Background: Autoimmune demyelinating disorders, such as multiple sclerosis (MS) and neuromyelitis optica spectrum disorder (NMOSD), are caused by persistent inflammation and damage to the central nervous system. Cognitive impairment (CI) is a growing challenge in these diseases, underscoring the need for a thorough exploration of its prevalence and risk across various subtypes. This study aimed to assess the prevalence and odds of CI using the Symbol Digit Modalities Test (SDMT) in various MS subtypes and NMOSD.

Materials and methods: A case-control study involving 616 participants, including healthy controls (HC) and individuals with different MS subtypes (Relapsing Remitting MS (RRMS), Secondary Progressive MS (SPMS), Primary Progressive MS (PPMS)), clinically isolated syndrome (CIS), and NMOSD, was conducted. CI was defined as SDMT z-scores 1.5 standard deviations below the HC average. The chi-square test was used to assess the risk of CI.

Results: The prevalence of CI varied across different groups: HC (10.7%), RRMS (33.8%), SPMS (71.3%), PPMS (62.8%), CIS (19.2%), and NMOSD (32.8%). Odds ratios (OR) for CI were significantly increased in RRMS (OR: 4.23, confidence interval (CI): 2.18-8.22, P < 0.001), SPMS (OR: 20.58, CI: 10.36-40.88, P < 0.001), PPMS (OR: 14.02, CI: 5.80-33.86, P < 0.001), and NMOSD (OR: 4.04, CI: 2.07-7.87, P < 0.001) compared to HC.

Conclusion: This study emphasizes a significantly increased risk of CI in MS subtypes and NMOSD compared to HC. Although no significant difference in CI risk was found between individuals with RRMS and NMOSD, those with progressive forms of MS exhibited notably higher risks of CI.