How is aphasia, or the loss of words, linked to multiple sclerosis?

Aphasia, or the loss of words, until recently was not considered a clinical manifestation of multiple sclerosis (MS) because MS primarily affects the white matter of the brain and spinal cord, while aphasia is typically associated with diseases of the grey matter. However, a recent multi-center study investigating the prevalence of aphasia in MS found that nearly 40% of individuals with MS demonstrate markedly reduced word-finding skills. Aphasic disorders may be observed in two different situations in MS. The most common situation is experiencing difficulty generating the names of people, places and things over the disease course, while the second situation is experiencing acute aphasia during or following an exacerbation.