The neural noise hypothesis: Evidence from processing speed in adults with multiple sclerosis

On measures of speeded performance, adults with multiple sclerosis (MS) typically respond more slowly than do adults without MS. A review of 12 published studies yielded 38 pairs of response times (RTs) in which each pair consisted of a mean RT for a sample of persons with MS for an experimental condition and the corresponding mean RT for a sample of persons without MS. The primary result was that, across the 38 conditions, RTs for individuals with MS increased linearly as a function of RTs for persons without MS. Because MS involves demyelination of the axons in the central nervous system (CNS), it is suggested that this result provides support for the neural noise hypothesis of cognitive aging.