Multiple sclerosis is a progressive autoimmune disease that damages the insulating covers of brain cells. Depending on the brain region affected, it causes symptoms such as physical and mental dysfunction, fatigue, pain, depression, and anxiety [R+].

This disease mainly affects young adults and is marked by a loss of myelin (demyelination) in the white matter of the brain. 

The usual pattern is one of recurrent attacks followed by partial recovery (see MULTIPLE SCLEROSIS, RELAPSING-REMITTING), but acute fulminating and chronic progressive forms (see MULTIPLE SCLEROSIS, CHRONIC PROGRESSIVE) also occur. (Adams et al., Principles of Neurology, 6th ed, p903)