Applegate says the diagnosis was wrong
Actor Christina Applegate announced Tuesday that she had been misdiagnosed with multiple sclerosis after years of believing she had the condition, according to CBS News. She shared the news on her podcast, MeSsy, where she and actor Jamie-Lynn Sigler discuss life with MS.
Applegate said the revelation has not brought relief. Her symptoms, which affect her daily life and mobility, still have no explanation. "You don't get misdiagnosed and then all of the sudden I'm better," she said on the podcast. "If anything, I've gotten worse. So I'm back at square one where I don't know what's going on with me."
She said her doctors will now investigate what has been happening since 2021 and why the misdiagnosis occurred.
How common is MS misdiagnosis?
In a follow-up episode, Dr. Marwa Kaisey, an associate professor in the neurology department at Cedars-Sinai Medical Center, said almost 1 in 5 people told they have MS "didn't actually have it." She described misdiagnoses as "fairly common."
Dr. Robert Brumel, director of the Mellon Center for MS at Cleveland Clinic, told CBS News that the largest studies of misdiagnosis risk have found that between 15% and 20% of patients diagnosed with MS turn out not to have the condition. The center cares for more than 11,000 patients with the disease.
MS is a condition in which the immune system attacks the central nervous system. According to the National Multiple Sclerosis Society, symptoms vary from person to person and the disease can progress in different ways.
Why the diagnosis is hard to get right
No single test confirms MS. Dr. Josef Gutman, director of NYU Langone's Long Island Comprehensive MS Care Center, said many symptoms are not specific to the disease. "It's sort of the story, combined with MRI imaging, combined with other markers like spinal fluid, that help us make the MS diagnosis," he said. He contrasted it with diabetes, saying MS is not a case where one blood test settles the question.
Brumel said the root cause of a misdiagnosis is typically that abnormalities on brain scans were misinterpreted. Brain lesions are considered a hallmark of MS, but they can also be caused by high blood pressure, smoking or migraines. More advanced MRI sequences can help distinguish MS lesions from those with other causes.
Brumel added that MS can sometimes be a "gratifying solution" for a patient with many symptoms because it is seen as a single root cause. He said some patients he has seen had fatigue caused by sleep or thyroid disorders, while rheumatoid conditions or fibromyalgia explained pain and swelling.
What happens when a misdiagnosis is suspected
Brumel said misdiagnosis is most often discovered when a person seeks a second opinion because symptoms are not improving. That does not always mean the diagnosis is wrong, but it can prompt more advanced testing, such as specialized MRI sequences, a spinal MRI or spinal fluid analysis that can identify abnormal immune proteins.
If MS is ruled out, doctors look for other explanations, including autoimmune conditions, migraines and chronic pain or fatigue syndromes. Brumel called fibromyalgia a "commonly identified diagnosis that mimics MS." He said an incorrect diagnosis "really sidetracks things," though he noted that the most commonly used MS treatments are "very safe" and would not endanger a person's health.
New diagnostic criteria developed by an international expert panel were published in 2025 to reduce the risk, and Brumel said they are more specific, particularly for interpreting brain lesions.
Advice for patients
Brumel said anyone concerned about a diagnosis should feel comfortable seeking a second opinion, which can also connect patients with other resources even if the original diagnosis is right. "MS is a life-changing diagnosis, and anytime somebody is facing something like that, I always think a second opinion is potentially in order," he said.
Patients can also look for an MS specialist. The National Multiple Sclerosis Society keeps an online registry and map of care centers and specialists nationwide, which Brumel called a "really good starting point." Gutman said specialists are likely to know current criteria, recognize mimicking conditions and have access to more specific tests.
