Ehrlé Nathalie, Omigie Diana, Saenz Amaya, Debouverie Marc, Rumbach Lucien, Chaunu Marie-Pierre and Bakchine Serge
Objective: It is widely accepted that working memory (WM) impairment has a high incidence in multiple sclerosis
(MS). However, this WM impairment has rarely been analyzed with reference to a cognitive model. The aim of the
study was to determine whether dysfunction in MS is due to WM or short-term memory deficits.
Methods: We assessed the components of Baddeley's WM cognitive model, which include the phonological loop,
visual sketch and central executive. Seventeen conditions implicating short term memory and executive functions
(flexibility, inhibition, manipulation) were carried out by128MS patients diagnosed with RRMS, and 30 age matched
healthy controls. Also assessed were three tasks of motor speed namely the Overt articulation rate, Digit-symbol
copy test and Digit-symbol coding test.
Results: In all but three conditions, the MS group scored significantly below the control group (Mann-Whitney
tests), suggesting a short-term memory deficit in MS. However, when performances in the central executive
conditions were expressed proportionally to a baseline, the patient group behaved in a similar way to the control
group. Finally, no relationship could be shown between the impairment in WM tasks and the motor speed tasks.
Conclusions: Our results suggest an impairment of short-term memory in MS patients but with a relative
preservation of WM. Critically, this conclusion is not in agreement with the widespread notion of WM deficit in MS