- Christina Applegate revealed on October 20 that she has been misdiagnosed with multiple sclerosis (MS), a condition she was told she had in 2021.
- Dr. Marwa Kaisey of Cedars-Sinai Medical Center explained that nearly 20 percent of people diagnosed with MS do not actually have the condition, with many having been on MS medication for years or even decades.
- Applegate says she is “back at square one” because her debilitating symptoms persist and the true cause of her illness remains unidentified.
Christina Applegate Reveals MS Misdiagnosis, Says She Is “Back at Square One”
On October 20, Christina Applegate publicly disclosed that she has been misdiagnosed with multiple sclerosis, the condition she was told she had in 2021 and has been managing — along with its severely debilitating symptoms — ever since. The revelation came during an episode of her podcast MeSy, which she co-hosts with fellow actress Jamie-Lynn Sigler, and it has drawn widespread attention not only because of Applegate’s celebrity profile but because of what the episode reveals about how frequently MS is misdiagnosed in the broader patient population.
Nearly One in Five MS Patients May Not Actually Have the Condition
To contextualize Applegate’s experience, Dr. Marwa Kaisey — an associate professor in the department of neurology at Cedars-Sinai Medical Center — joined the podcast to explain the scale of the misdiagnosis problem. Her findings are striking: nearly 20 percent of individuals who receive an MS diagnosis are ultimately found not to have the disease at all.
“Almost one in five of these people who’d been told they had MS, some for decades, didn’t actually have it,” she explained. “And a majority of them were on medication to treat their MS.”
Dr. Kaisey further clarified to Applegate and Sigler that diagnosing MS is inherently complex because there is no definitive single-step diagnostic tool available to clinicians.
“It’s not like we have something like a pregnancy test that says, ‘Yes. You have it.’ ‘No. You don’t.’ It’s a list of criteria,” she said.
Why MS Is So Difficult to Diagnose Accurately
The difficulty in achieving a correct MS diagnosis is well-documented in medical literature. A report published in the National Library of Medicine, titled Multiple Sclerosis Misdiagnosis: A Persistent Problem to Solve, confirms that “no specific disease biomarker exists,” making the diagnostic process inherently uncertain.
The report states: “MS has heterogeneous clinical and imaging manifestations, which not only differ between patients, but also vary in individual patients over time. Disease signs and symptoms, presence of oligoclonal bands (OCB) and MRI findings have limited specificity, and misdiagnosis remains a problem with significant clinical and psychosocial implications for both patients as well as health care providers.”
The same report acknowledges the gap in understanding the full scope of the problem: “Although the problem of MS misdiagnosis is known, true incidence and prevalence is not.”
Making matters more complicated, a wide range of other medical conditions can closely mimic MS and lead to incorrect diagnoses. According to the report, these include: “Migraine, cerebral small vessel disease, fibromyalgia, functional neurological disorders, and neuromyelitis optica spectrum disorders, along with uncommon inflammatory, infectious and metabolic conditions.”
Applegate’s Symptoms Persist Despite the Updated Diagnosis
For Applegate, the revelation that she does not have MS has not brought relief. Her symptoms — which she describes as consistent with those of “someone with MS” — have not disappeared, and in some respects have worsened. She acknowledged during the podcast that she has “every single” symptom of MS but that “something else is going on.”
Applegate recounted the moment her doctor delivered the unexpected news, describing it as emotionally complicated rather than cause for celebration.
“This may come as great news, but to me, I’m back at square one,” Applegate said. “It’s hard to say that [my doctor] came into my room and she said, ‘Congratulations, you don’t have MS’.”
She added that the update to her diagnosis does not represent a recovery. She is “not happy at all” about the news, stressing that it is not as though she has suddenly “gotten better.”
“If anything, I’ve gotten worse in some ways.”
She noted that new technology played a role in uncovering the discrepancy in her diagnosis, saying: “It’s clear now that they’re finding something different. Something else is going on.”
Why This Matters
Applegate’s public disclosure brings renewed attention to a systemic challenge in neurology: the misdiagnosis of multiple sclerosis affects a substantial portion of patients, many of whom spend years — sometimes decades — being treated for a disease they do not have, while the actual underlying condition goes unaddressed. The consequences are far-reaching, encompassing unnecessary medication exposure, psychological distress, and delayed treatment for the true illness. As diagnostic technology continues to evolve, Applegate’s case illustrates both the promise of new tools and the profound emotional and medical uncertainty that patients face when a long-held diagnosis is overturned. Her willingness to discuss this openly on MeSy with Jamie-Lynn Sigler has helped amplify a conversation that affects a significant and often invisible segment of the chronically ill community.
Frequently Asked Questions
How common is MS misdiagnosis?
According to Dr. Marwa Kaisey, associate professor in the neurology department at Cedars-Sinai Medical Center, nearly 20 percent of people diagnosed with MS — or almost one in five patients — do not actually have the condition. Many of these patients had been receiving MS-specific medication before the misdiagnosis was identified.
Why is multiple sclerosis so frequently misdiagnosed?
There is no single definitive test for MS. Diagnosis relies on a set of clinical criteria, and the disease shares symptoms with numerous other conditions including migraine, fibromyalgia, cerebral small vessel disease, and neuromyelitis optica spectrum disorders, among others. MRI findings and other diagnostic indicators have limited specificity, making accurate diagnosis particularly challenging.
What does Christina Applegate’s misdiagnosis mean for her health going forward?
Applegate’s symptoms have not resolved following the updated diagnosis — she has described them as worsening in some respects — and the root cause of her illness currently remains unknown. She has stated that new technology helped reveal the discrepancy and that doctors are now working to determine what is actually causing her condition.
