Subjective complaints, verbal fluency, and working memory in mild multiple sclerosis

Patients with mild multiple sclerosis (MS) regularly report subjective complaints characterized by generalized cognitive inefficiency. A feature of these complaints is reduced verbal fluency, for example, losing the thread of conversation. Mild MS patients and controls were compared on subjective complaints, verbal fluency, and working memory, and the possible role of working memory was investigated. As predicted, subjective difficulties and verbalfluency each correlated with working memory. Subjective difficulties and verbal fluency were also related. Within the control group, the subjective difficulties were associated only with depression. On the other hand, in the MS group, subjective difficulties were unrelated to affective state but were correlated with working memory. For the patients, partialing out depression and anxiety did not influence any of the correlations involving subjective difficulties, verbal fluency, or working memory. These findings support the proposal that working memory impairment underlies subjective complaints of mild MS patients and that verbal dysfluency is part and parcel of this phenomenon.