[Contribution of ecological evaluation of executive disorders in multiple sclerosis]

Multiple sclerosis (MS) is a major cause of neurological disability among young adults. The cognitive disorders are the second cause of alteration of quality of life after physical handicap and are often responsible for loss of social-occupational adaptability. The prevalence of cognitive disorders is 40 to 65%. The alteration of executive functions predominates whereas instrumental functions are generally preserved. The assessment of these disorders is often underestimated by the usual battery of neuropsychological tests. However, the link between psychometric results and executive difficulties of daily life is uncertain.

To evaluate the sensitivity of an ecological test compared to standard psychometric tests in assessment of executive disorders in MS.

Twenty subjects with clinically definite MS were matched for age, sex and pre-morbid intellectual level with control subjects. A battery of neuropsychological and ecological tests was applied to all subjects. The performances on these tests formed a global score of executive function (SFE). The "paper and pencil" multiple errands test was used as the ecological test to examine planning and goal-oriented behavior. We also assessed fatigue and depression with the Fatigue Severity Scale and the Beck Depression Inventory.

There was no significant differences between MS patients and controls in neuropsychological executive tests, except for verbal fluencies (p=0.01). The performances were significantly decreased in the MS group for the multiple errands test (p=0.01). 75% of MS subjects have a pathological score for this test. There was a significant link between the performances with this test and SFE (p=0.009).

Executive disorders are underestimated in MS. However, we suggest that an ecological approach is more reliable than standard neuropsychological tests to estimate the cognitive difficulties in daily life in MS subjects. The results of our study favor further research to ascertain the usefulness of ecological assessment in MS.