Use of rating scales to reflect cognitive and mental functioning in multiple sclerosis

46 patients with clinically definite multiple sclerosis were studied to compare intellectual function (Wechsler Adult Intelligence Scale) with other clinical expressions of the disease. Estimated premorbid I.Q. was compared to actual I.Q. 35% had I.Q. decrease of 0-14 points (clinically insignificant); 56% had mild to moderate I.Q. decrease of 15-29 points and 8% had more serious I.Q. decrease of 30 or more points. Decrease in I.Q. did not correlate with any other neurological deficit.