Cognitive and neurobehavioral features in multiple sclerosis.

Multiple sclerosis (MS) is the most common nontraumatic neurological condition of early and middle adulthood. Cognitive and neurobehavioral problems associated with this disorder are common. Approximately 50% of MS patients experience lifetime clinical depression, and at least 50% will experience significant cognitive difficulties. Fatigue is also extremely common and disabling in MS and appears to be associated with sleep problems and primary neurological features, in addition to secondary factors, including depression and pain. Quality of life is affected in MS by all of these factors and is an especially salient issue given that patients often live for many years following diagnosis. In this article, we explore the literature on cognitive and neurobehavioral features in MS, provide a commentary on the state of the literature and make suggestions for research directions over the next 5 years that would move the field forward significantly.