In 1943 Sugar and Nadell1 reviewed the literature concerning mental changes associated with multiple sclerosis. Their survey disclosed considerable disagreement regarding the question of intellectual loss. They said:
Charcot and Dupre referred to progressive dementia characterized by defects of memory, hallucinations, markedly expansive moods.... Hunt and Kraeplin were of the opinion that this disease was accompanied by slight mental changes, and that in a large number of cases those psychical alterations were merely transitory.
To our knowledge, estimates of intellectual impairment as a consequence of the disease, based upon clinical impressions, have varied from 2% (Cottrell and Wilson2) to 72% (Ombredane3). Although the procedure used by Ombredane did not provide a quantitative basis for group comparisons, he carefully studied 50 patients with multiple sclerosis and concluded that 36, or 72%, had very clear intellectual losses. He believed that the main loss was represented by difficulty in initiating