Doctor weighs in on MS misdiagnoses after Christina Applegate’s revelation

American actress Christina Applegate, who is often remembered for her role as Kelly Bundy on the hit TV show Married With Children that aired from the late 80s to late 90s, said this week that she was wrongly diagnosed with multiple sclerosis.

Ms. Applegate first announced in 2021 that she had been diagnosed with the disorder that causes the immune system to attack the cells in the central nervous system.

On Tuesday, The Globe and Mail spoke with Dr. Mark Freedman, an internationally recognized neurologist who serves as director of the Multiple Sclerosis Research Unit at the Ottawa Hospital, to learn more about the disease and how common it is to be misdiagnosed.

What is MS?

MS is considered an autoimmune disease. There are many autoimmune diseases. Every organ of the body has an autoimmune disease associated with it.

In MS, the autoimmune target is the insulation of the wires of the central nervous system, called myelin.

What are some of the symptoms of MS?

Anywhere you have the central nervous system, myelin is open to attack from the immune system. It includes what some people don’t realize: the optic nerve.

The optic nerve is an extension of the brain and it’s coated with myelin, similar to the way the rest of the brain and spinal cord are.

Your brain controls everything, right? So depending on where the attack occurs, you could have a multitude of different symptoms, or you could have no symptoms at all.

How is MS diagnosed?

We actually just published a brand-new series of criteria about a year ago. This was an international effort at trying to really line up the clues for MS.

Every rendition of our diagnostic criteria had two things in mind. Number one: make sure that if you put the label of MS, it really is MS. The second is to try to diagnose the disease earlier, so there’s an opportunity for treatments. The earlier you introduce an effective treatment, the better the long-term outcome.

How common is it for patients to be misdiagnosed with MS?

In Canada, I would say it’s very uncommon. Most of the neurologists in our country are highly trained in usually large academic centres. We always train fellows. That’s not the case in other countries, such as the U.S.

The disease has become so complex, not only in terms of the diagnosis but also in the therapies that we apply.

Quite frankly, there’s not enough trained MS specialists in the U.S. to handle all their patients.

Why is it key for patients to be able to receive the correct diagnosis?

Psychologically, would you really want to be labelled with a disease you don’t have? I would err on the side of “This could be MS, but I’m not convinced of it, and I need to do more tests or I need more time.”

The drugs that we’re using today are actually quite complex and very expensive. Do I want to commit a patient to a therapy they don’t need and could be potentially harmful to them? I don’t want to do that. Our Hippocratic Oath when we became doctors is to first do no harm.

Is MS hereditary?

Yes. The data varies a little bit, but most of the time we say that if you have a first-degree relative – mother, father, sister, brother – with MS, your chances are 30 to 50 times the population risk. So about three-to-five-per-cent lifetime risk, because the incident rate in Canada overall is about one in 1,000.

What are you thinking about as you look to the future and how to best support patients?

There’s so much that we need to know.

Years ago, we pioneered the use of autologous stem cell treatment for MS in Ottawa. We are still the leading centre in Canada that does these treatments for people who have very aggressive forms of the disease. In those individuals, we’ve been able to stop it cold and they’ve done very well.

It’s quite an extreme procedure to completely remove an immune system and replace it with patients’ own stem cells. We still do one or two a month from all over Canada.

Even if we stop all inflammation in patients, some patients still continue to progressively get worse. That is a different type of inflammation that is not currently targeted by the therapies we have, but there are some new ones on the horizon.

This interview has been edited and condensed.