Having just mentioned the Blood Brain Barrier, it’s a good time to discuss Multiple Sclerosis. MS is an autoimmune disease. Auto immune diseases are strange in that the same immune system that guards our body against infections for some reason turns against certain our own body and attacks them in the same manner.
When this occurs in the brain to cause MS, lymph cells attack the blood brain barrier to break it down, allowing other immune system components into the brain where they attack the myelin, the insulation on neurons. When this happens, the myelin becomes damaged to the point the nerves no longer can transmit information. The name multiple sclerosis refers to the multiple scars (known as plaques) that form as a result of the immune attack. Although myelin also coats peripheral nerves, they are seldom involved in the disease.
Neuroscientists know a great deal about MS, but they do not know what causes or triggers this autoimmunity. Some believe it results from a prior infection as if an immune response against the infection gets confused and attacks the BBB and myelin instead. Genetics does not play a strong role in this disease. The frustrating aspect about this disease is it is intermittent, meaning a person may have one or two attacks and no others. Another person may have attacks one after another in a very progressive course. Once the diagnosis is made, there is no way to predict what will happen. The good news is that there are at least five-modifying treatments that are approved for treatment and have various degrees of efficacy.