To investigate the impact of age on recovery from relapses in multiple sclerosis when controlled for an individual's inherent factors.

The first and last-ever relapse data (168 relapses in 193 patients) from a population-based cohort of multiple sclerosis were studied using paired analyses for age at the time of relapse and maximum recovery from the peak deficit attained during that relapse. Two relapse-outcome measures were used: 1) change from peak deficit to maximum recovery in raw functional system score related to the relapse (ΔFSS), 2) change from peak deficit to maximum recovery in Extended Disability Status Scale (ΔEDSS) score. 

The first relapse (age, mean±SD= 30.2±8.8) and last-ever relapse (age, mean±SD= 45.0±10.0) were separated by 15 years. Older age was associated with worse recovery in the ΔFSS outcome (p = 0.002) and ΔEDSS outcome (p < 0.001) in a given individual. A multivariate analysis of the ΔFSS outcome identified previously suspected variables; having spinal cord/brainstem/cerebellar syndrome (as opposed to optic neuritis) (p<0.001) or relapse fulminance (p=0.004) as additional co-variates impacting recovery. An increase in the brainstem/cerebellar location relapses was observed with aging (1st relapse 19%; last relapse 31.5%, p=0.005).

When relapses from the same individual are studied through paired analyses; recovery from relapses in multiple sclerosis declines with increased age, independent of relapse location, while a concomitant increase in the preponderance for brainstem/cerebellar relapses with increased age is observed. Understanding biological mechanisms underlying these observations could help future targeted drug development in multiple sclerosis.