Early detection of cognitive dysfunction in patients with multiple sclerosis: Implications on outcome

Objective: Cognitive impairment in multiple sclerosis (MS) has a complex relationship with disease progression and neurodegeneration. The aim of this study was to shed light on the importance of early detection of cognitive impairment in MS patients. Methods: The study comprised two groups of definite MS patients, relapsing remitting multiple sclerosis (RRMS) and secondary progressive multiple sclerosis (SPMS), each with 25 patients. Physical disability was assessed using the Expanded Disability Status Scale (EDSS), while the risk of secondary progression was assessed using the Bayesian Risk Estimate for Multiple Sclerosis (BREMS). Cognitive functions were assessed using the Brief International Cognitive Assessment for Multiple Sclerosis (BICAMS) and Controlled Oral Word Association Test (COWAT). Assessment of neurodegeneration was done using optical coherence tomography (OCT) via quantification of retinal nerve fiber layer (RNFL). Results: MS patients with higher RNFL thickness demonstrated a larger learning effect size than patients who had lower values in RNFL thickness regardless of MS type. RRMS patients showed significant improvement in delayed recall after giving cues than SPMS. The symbol digit modalities test was the only neuropsychological test that showed a significant negative correlation with EDSS (P= 0.009). There was a statistically significant negative correlation between BREMS scores and performance in all neuropsychological tests. Conclusion: Inclusion of neurocognitive evaluation in the periodic assessment of MS patients is mandatory to detect patients at increased risk of secondary progression. The thickness of RNFL is suggested as a method to estimate the expected benefit of cognitive rehabilitation, regardless of MS type.