TAMPAAnnette Funicello, who died this week at age 70 of complications from multiple sclerosis, was diagnosed just as scientific knowledge about the disease was on the brink of expanding.The Food and Drug Administration approved the first drug for multiple sclerosis in 1993, a year after the beloved original Mouseketeer announced she had the condition. Around the same time, magnetic resonance imaging (MRI) came into widespread use, which revolutionized diagnosis of the disease.It still isn't known what causes multiple sclerosis, in which the immune system appears to attack the protective covering of nerves. As that covering, known as myelin, breaks down, communication between the brain and the spinal cord deteriorates, causing symptoms including difficulty walking or speaking, vision disturbance or loss, fatigue, dizziness, muscle weakness and tremors. Some people have a single flare-up of symptoms and never have another; others have a flare-up followed by remission that lasts months or years. For a small group of patients, symptoms progressively worsen, shortening their lives. Although anyone can get MS, it's more common in women than in men and usually strikes between ages 20 and 50. Dr. Derrick Robertson, director of the MS Center at the University of South Florida in Tampa, spoke with the Tampa Bay Times this week about a disease that affects more than 2 million people worldwide.Annette Funicello lived more than 20 years with MS. Is that typical?Life expectancy is increasing. We now see disability on average within 10 to 15 years of diagnosis. But the new therapies that have been developed in the last 20 years have really extended life expectancy. They calm down the disease process, slow it down and lessen disability, so life expectancy with MS is within five years of the regular U.S. population. That's a good indication that our newer medications are modifying the disease.What are the current theories about what causes MS?We still don't know the precise cause. It seems to be a perfect storm of events. First, there is likely a genetic component. Then there is an environmental factor, probably linked to sunlight exposure. Then there is a trigger, possibly a viral exposure or something similar that disturbs the immune system, causing it to turn on itself and periodically attack the brain and spinal cord. So it's genetics, environment and then the trigger.What is it about sunlight that influences MS?You see more of the disease the further north you go. So you typically see more MS in Canada and in the northeastern United States than you do in the southern U.S. Vitamin D is made from sunlight and helps regulate the immune system. MS patients seem to get less sun exposure and make less vitamin D. MS is almost never diagnosed along the equator.But Annette Funicello was in all those beach movies. Why didn't that protect her? She might have had more aggressive disease and possibly not lived as long had she not had the sun exposure associated with those movies of her youth. Remember, we think it takes a perfect storm of factors to get MS.Why did MRI revolutionize diagnosis of MS?Flare ups, those periods of neurological inflammation, leave scar tissue behind, scar footprints. MRI shows us that scar tissue in the brain and on the spinal cord that are the hallmark signs of MS. If the nerves of your eyes are affected, you get vision problems or blindness. If it's in the left arm, you get left arm paralysis. Scar tissue can form anywhere. If it forms in an area that is neurologically very important, say your swallowing center nerves, you can unfortunately be left with lifelong swallowing difficulty.Is there any good news on the research front?Yes. We have active clinical trials looking at future medications, those that are in early design. Most work on the immune system to calm it down and keep it from causing inflammatory episodes that lead to MS attacks. The first medication for MS wasn't approved until 1993. It did okay, and was certainly better than nothing. Newer drugs are better tolerated and stabilize MS. The difficulty is, it's hard to predict which drugs will work for each patient.How close are we to a cure?A cure is difficult to find without a clearly defined cause. But we're moving in the right direction.