For MS Awareness Month in March, we revisit an episode of the National Multiple Sclerosis (MS) Society’s Ask an MS Expert program on the Real Talk MS podcast featuring neurologist Andrew Solomon, M.D., professor of neurological sciences and division chief of multiple sclerosis at the Larner College of Medicine.
The McDonald Diagnostic Criteria
Dr. Solomon discusses the recently updated McDonald Diagnostic Criteria, which helps doctors diagnose multiple sclerosis faster and more accurately—and when MS is diagnosed earlier, people can start treatment sooner, which can lead to better health outcomes. The criteria were updated in fall 2025; driven by new data or new research that suggests there may be ways to diagnose patients earlier, updates have been made approximately every seven years since 2001.
“When MS is diagnosed earlier, people can start treatment sooner, which can lead to better health outcomes.”
“The McDonald criteria are really the consensus criteria that MS specialists use now to make the diagnosis of MS,” Solomon explains. “It’s incredibly important to have one set of criteria because we want to make sure we’re all talking about the same thing and that the research we do to help patients with MS also uses the same criteria so we know that it helps those patients.”
On the differences between the previous criteria and the new criteria, Solomon says, “The easiest way to think about the changes broadly is that there’s a variety of new diagnostic pathways, a variety of new ways that patients could be diagnosed with MS, and perhaps earlier than using previous criteria. And then there’s also some aspects of the criteria where there’s slight changes or recommendations that may improve diagnostic accuracy and prevent misdiagnosis of MS, or somebody receiving a diagnosis of MS who doesn’t have it.”
Top Takeaways
“I think the new criteria has some pretty significant changes,” Solomon says. “I think the top takeaway is that this is a really big change in the field and we’ve sort of balanced early diagnosis with misdiagnosis, and simplicity with flexibility, and overall there’s new opportunities for early diagnosis of MS here and ultimately improved outcomes in patients or prevention of disability using these new criteria.”
Solomon concludes, “It’s more complex than prior criteria, and while some pathways are quite simple for diagnosis, others in order to facilitate early diagnosis are a little bit new or more complex. So it’s going to take some training and efforts to implement this criteria broadly.”
“We’ve sort of balanced early diagnosis with misdiagnosis, and simplicity with flexibility, and overall there’s new opportunities for early diagnosis of MS here and ultimately improved outcomes in patients or prevention of disability using these new criteria.”
An investigator on numerous local and national multicenter clinical and translational studies evaluating therapeutic and prognostic interventions for MS, Solomon has been recognized nationally and internationally for clinical and research contributions centered on MS diagnosis, differential diagnosis, and misdiagnosis. His current work focuses on the evaluation of novel imaging biomarkers for the diagnosis of MS.