Alteration profile of executive functions in multiple sclerosis

Executive functions (EF) in multiple sclerosis (MS) have been only partially studied, mainly trough the evaluation of subfunctions. The main objective was to analyse the EF alteration profile in a patients with MS sample.

Case-control study, 100 patients with MS and 30 controls were evaluated by the following tests: Comprehensive Trail Making Test, Stroop Test, Wisconsin Card Sorting Test, picture completion, letter-number sequencing, comprehension and similarities of the WAIS-III scale, phonological and semantic fluency, zoo map test, temporal judgment and behavioural Dysexecutive Questionnaire (DEX-Q) of the Behavioural Assessment of the Dysexecutive Syndrome. Scores below normative values were considered pathological. Factorial analysis was used to simplify the deficits, and multiple regression and ANOVA statistics were used to analyse the relationship between clinical and cognitive variables.

Seventy-four patients had a recurrent-relapsing course, the mean degree of disability by Expanded disability Status Scale (EDSS) was 2.7 and the mean time of evolution was 9.94 years. Eighty-five per cent presented alterations in 3 or more EF tests and 71% in 5 or more. In the factorial analysis, three groups of functions were involved: (i) cognitive flexibility (ii) inhibition and (iii) abstraction ability. Patients with a progressive course and a high EDSS had a significantly worse performance (P < 0.05). The patients showed a low awareness of their deficit in the DEX-Q.

Cognitive flexibility, inhibition and abstraction ability were the three components of EF most deficient. The patients with the worst performance were those with progressive forms and a high EDSS.