Information Processing in Multiple Sclerosis Patients

JUAN E KAMIENKOWSKI; MILENA WINOGRAD; SANDRA VANOTTI; M LAURA SALADINO; FERNANDO CACERES; MARIANO SIGMAN

Buenos Aires, Argentina

Congreso; International Neuropsychological Society 2008 Mid-Year Meeting; 2008

When two tasks are presented simultaneously or at a short stimulus onset asynchrony (SOA), a systematic delay in the execution of the second task is observed while response times (RT) to the first task are unaffected. This phenomenon, referred as Psychological Refractory Period (PRP), has been widely used in normal subjects to understand the temporal organization of different stages of information processing. Here we investigate PRP performance in patients with Multiple Sclerosis (MS) with Relapsing-remitting pattern.  Since a primary aspect of the physiopathology of MS is demielinization of long distance fibers, we hypotesized that the dynamics of information processing may be affected, even at early stages of the disease when no other cognitive impairments are evident. Cognitive performance was evaluated using the Brief Repeatable Battery-Neuropsychology, Trail Making and Conners Performance Test. We found that performance in dual-task is significantly impaired in MS patients. First, MS patients perform slower than controls in PRP tasks. This is particularly accentuated in the response time to the second task, which is affected by dual-task interference. Second, we observed a strong effect of notation in the patient group: the difference between the RT´s in words-written numbers vs. digits-written numbers trials was significantly higher than in the control group. In addition, patients manifested a systematic difficulty in executing both tasks in close succession. From this preliminary experiment, we can conclude that MS patients with no evident signs of cognitive disabilities, have already compromised some particular aspects of information processing.