Dr DeLuca provides an overview of changes in cognition and brain volume loss in patients with multiple sclerosis.
John DeLuca, PhD: Cognitive change in multiple sclerosis [MS], even early in the disease during clinically isolated syndrome, about a third of the patients with MS are already experiencing cognitive problems, primarily in cognitive processing speed. That increases to about 50% in persons with relapsing-remitting MS, and about 70% to 90% in those with progressive MS. So cognitive issues are really problematic. They’re usually observed in about 2 out of every 3 patients in a doctor’s office. It’s something that needs to be addressed because these cognitive problems, which are primarily processing speed, problems in learning and memory, and executive functions, have a significant impact on everyday life activities.
When we talk about brain volume loss, unfortunately, brain volume is lost with aging. However, in persons with MS, brain atrophy is about 3 to 4 times greater than what you see in normal aging. That becomes a fairly significant problem, particularly if you’re talking about individuals who are diagnosed very early in the disease. Brain volume loss, at least concerning cognition, is particularly prevalent in the area of the thalamus, but also in whole brain volume and cortical gray matter volume. But when you talk about the thalamus, you’re really talking about the primary areas that are involved with respect to cognition. That’s not necessarily the only areas, you see volume loss in the hippocampus, and you see volume loss in the basal ganglia. But particularly early in the disease, thalamic volume loss is a significant predictor of decline over time. It would be very important as a marker in a patient to see, will there potentially be a continued decline in cognition?
When you talk about brain volume loss from your typical clinical scan, unfortunately, I think clinicians are pretty much reliant on the radiological report or their own interpretation of visually examining the MRI. That’s not necessarily good enough when you’re looking at subtle changes, particularly early in the disease. So that becomes a challenge. Because we know that early cognitive impairment and early gray matter volume loss are the 2 best predictors of cognitive decline down the road. Unfortunately, the typical clinical scan is not going to provide the information in general that the normal clinician needs to have a good understanding of gray matter volume loss.
When we talk about measuring cognition in practice, unfortunately, probably the majority of clinicians do not assess cognitive function in persons with MS. You tend to have a better result in the larger centers, which are probably university-based centers, or larger centers, but in individual practices, cognition is usually not assessed with objective testing. Clinicians may often ask the patients about cognition, but we know from research data that asking patients for a self-report, that self-report is not necessarily related to actual cognitive impairment. It’s not even related necessarily to everyday life performance. Cognition needs to be assessed with objective testing. And there are tons of data on this. There are several studies showing that the neurologists’ evaluation and report, and self-report, and examination, are no greater than chance at identifying cognitive impairment. So it really needs to be done in the office. There are tools available to do cognitive screening so that the clinician can decide whether the patient needs to have a larger neuropsychological evaluation. But unfortunately, I think this needs to become standard of practice, and it’s not necessarily the case right now.
Transcript Edited for Clarity