Cognitive outcomes in late-onset versus adult-onset Multiple Sclerosis

Introduction: Recent studies show that cognitive impairment is more prevalent in older patients with Multiple Sclerosis (MS). However, whether this is the result of several years of a chronic disease or specific age-related changes is still unclear. Therefore, we aim to assess the outcomes in both classic and social cognition in lateonset MS (LOMS) and compare them to adult-onset MS (AOMS) when accounting for age and disease duration. Methods: In this cross-sectional study, a group of 27 LOMS patients (age of disease onset >50 years) was compared with patients with AOMS (age of disease onset between 18 and 50 years). Patients with AOMS were grouped based on age (AOAMS, n = 27) and on disease duration (AODMS, n = 27) in order that these variables are matched with LOMS. Their cognitive performance was evaluated using the Brief International Cognitive Assessment for Multiple Sclerosis (BICAMS) and the Revised "Reading the Mind in the Eyes" Test (RMET). Clinical and demographic variables were collected and analysed. Results: In general, both classic and social cognitive performance was inferior in the LOMS group when accounting for age and disease duration. We found a statistically significant negative correlation between age of disease onset and performance in all cognitive domains except for verbal memory. The presence of at least one vascular risk factor (VRF) was associated with slower information-processing speed (SDMT) (p = 0.006) and poorer RMET performance (p = 0.020). Discussion: A later age of MS is associated with worse cognitive functioning possibly due to the loss of neuroplasticity in an already aged brain. Conclusion: Patients with LOMS have worse cognitive outcomes than AOMS in both classic and social domains, especially when associated with the presence of VRF. Hence, health care providers and patients should not undervalue the importance of cognitive stimulating activities, management of VFR and socialization in this specific group of patients.