 Severe impairment is a major predictor of a low quality of life, unemployment, caregiver distress, and difficulty in driving; limitations in a patient's social and work activities are also correlated with the extent of impairment.Cognitive impairments occur in about 40 to 60 percent of patients with multiple sclerosis, with the lowest percentages usually from community-based studies and the highest ones from hospital-based.Impairments may be present at the beginning of the disease.