Executive Dysfunction in Multiple Sclerosis 1 Running Head: EXECUTIVE DYSFUNTION IN MULTIPLE SCLEROSIS Executive Dysfunction Syndrome in Multiple Sclerosis

Multiple sclerosis (MS) is a chronic disease affecting the central nervous system. Several authors consider that an attentional damage is the underlying cause of cognitive dysfunction in MS. However, while some studies of MS report attentional deficits, others suggest that attention remains unaffected by this disease. The presence of attentional deficits in MS thus remains a disputed matter. We suggest that these discrepancies stem from the use of a wide range of attentional tests, we need only consider that attention is not a unitary function, and that the convergent validity of the different tests has not been demonstrated. Thus our main aims are: to obtain a set of attentional tests which taps the whole range of attentional functions; to assess the clinical contribution of some reaction time tests derived from theoretical models of attention, which will be used along with classical psychometric tests; and to evaluate the convergent validity of the different tests employed. In our study MS patients exhibit diverse and specific attentional deficits. That is, they show an attentional profile consisting in a series of specific impairments in visual selective attention, (visual search and attentional capture), executive function (cognitive flexibility or capacity to overcome automatic responses) and sustained attention (fatigue problems). However, some aspects of these attentional components remain unaffected (concentration and accuracy in selective attention, alertness, interference from distractors, and capacity for maintaining information with low memory loads in executive control). We also discuss the relationship between attentional deficits and cognitive and affective disorders in MS.