Experts in neurology comment on the lack of definition of cognitive impairment in multiple sclerosis, highlighting an inability to adequately screen for and measure this disease symptom.
Ahmed Obeidat, MD, PhD: This kind of brings us to the definition of cognitive impairment and people like to ask about definitions. And when we think about cognitive impairment in MS [multiple sclerosis], how can we define it? And is there a good way to define it?
Jeffrey Wilken, PhD: That’s been the trouble. One of the problems, and one of the reasons why it’s ignored is because neuropsychologists have not traditionally given the neurology field a good way to measure this. We can do our 5- or 6-hour batteries, but what is a neurologist going to do in the office? Hence, defining it has been difficult. There are some screening tests out there right now. The Symbol Digit Modalities Test, or SDMT, is one that’s used to kind of at least screen. But it’s not a measure of cognition as much as it is a measure of will this person kind of go thumbs up or thumbs down on a larger battery, maybe of neuropsychology tests. Thus, it doesn’t tell us everything we want to know. As far as how we define cognitive impairment though, with MS if we were look at this more broadly and not just at a one single screening test, like everything with MS, like every physical symptom we see in MS almost, it depends on the person, it crosses the spectrum. We could have a person with no cognitive impairment in MS. But as Dr Schapiro was saying up to 60%. Depending on where you are, depending on comorbidities, it’s probably even a little bit higher. I know the research says 60%. But I think it might be a little higher than that. But I will say that when you do find a person who has impairment in cognition MS, what you’re probably talking about is anything between having one or two areas of a problem. Maybe attention’s a little bad or the thinking speeds, a little bad crossing the spectrum to multiple areas of impairment, where you get somebody who almost looks, I wouldn’t say they look like a dementia patient, but we’re getting toward so many cognitive deficits that we are needing to take care of that patient because the deficits are so bad or they can’t work or they can’t function without some assistance. It crosses the spectrum.
Randall Schapiro, MD, FAAN: And the spectrum is really big. Before we had drugs for MS, we used to say that a third of the people who got MS ended up in a nursing home, another third of the people who got MS ended up with significant disability but ended up in the home environment. But there was another third of people who had MS who did fairly well, and they dropped off, they stopped seeing doctors. I used to see them. I know they exist. And whenever they did studies, they found these people. Matter of fact, we even had a term, we talked about “benign multiple sclerosis.” I don‘t like that term. It’s more mild multiple sclerosis. These individuals had MS. But they did fine in the community. Thus, every single person with MS is different, so some could be demented, and I‘ve seen that. And some can be rocket scientists.
Jeffrey Wilken, PhD: That‘s interesting. I had a patient in my office yesterday, not only did she have MS, but she had COVID-19 these past few months. She was convinced that her cognitive functioning had to dramatically changed due to the MS, the COVID-19, whatever it was, but she tested absolutely normal. And I was talking to my students and said, “I’m really glad you saw this because you don’t get to see this very often, but there are some people who will come in and be just fine.” And then they see the other ends of the other parts of…
Randall Schapiro, MD, FAAN: And you would see it more in selected people because people who are normal may not even get your eyes.
Jeffrey Wilken, PhD: They don’t usually…
Ahmed Obeidat, MD, PhD: That’s right. And do you think there are some predictors of cognitive impairments and things that when you see a person in a clinic, would you be able to say, “Well, this is a person I need to really do a cognitive assessment?” I really do, or I’m just going to be OK, I’m monitoring and doing maybe a screening, like an SDMT or I need to get a whole battery.
Transcript Edited for Clarity