Changes in Ability to Smell Tied to Neuroaxonal Damage in MS

Odor discrimination and identification (DI) represent an “irreversible marker” of neuroaxonal damage for patients with MS that is associated with progression regardless of relapse activity, cognitive deterioration and worsening scores for the Expanded Disability Status Scale (EDSS), according to findings published in Multiple Sclerosis Journal. Gabriel Bsteh, PhD, and colleagues assessed whether longitudinal changes in odor DI predicted the long-term course of MS in a 6-year longitudinal prospective study, with 92 of 139 patients available for 6-year follow-up. Mean DI scores declined over time (baseline=27.8; Year 1=27.5; Year 2=26.3; Year 6=26.3; P<0.001) and negatively correlated with patient age as well as disease duration. In multivariable regression analyses, the study team found an association between lower absolute DI scores and a bigger decline in DI score over time with a greater probability of EDSS worsening (per −1 point: HRs=1.40 and 2.34, respectively), progression regardless of relapse activity (HRs=1.49 and 2.22, respectively), and cognitive worsening (HRs=1.75 and 4.29, respectively) at Year 6. Lower absolute DI scores and a bigger decline in DI score over time were not associated with the time to first relapse.