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Admitting he suffered a physical toll from the challenges, Osbourne explained, “Even though it was f***ing me up, I was having problems and overheating and, you know, I was having all these crazy things going on in that time period right after I got diagnosed.

“But I was still determined to participate… I was like, I’ll find a way to make this work because I want to do it and it brings me joy.”

Osbourne also opened up about the mental side of living with an unpredictable disease, including the depression that sometimes comes with it.

“I have to look at the fact that I have no control of how this thing is going to roll out in my body,” he continued. “But I do have control of how I’m choosing to treat it mentally, to the best of my ability.”

Osbourne didn’t shy away from the darker moments, acknowledging, “Yes, there is that depression side of things that does flare up,” before adding, “I have to keep telling myself I have a choice in how I choose to suffer with this.”

The British-American media personality also confessed that he sometimes feels like a bit of a “fraud.”

More than a decade after being diagnosed with the chronic disease, he said, he often meets people at MS events who received their diagnosis just a year ago but are having a far tougher time than he is.

He added that the disease “hasn’t stopped me and it hasn’t really slowed me down.”

Applegate, who recently revealed she was misdiagnosed with MS, chimed in, “Talk about being a fraud. I don’t even have it anymore. However, the “Married.. with Children” star made it clear she isn’t going anywhere, saying she’ll always remain part of the MS community in some form.

She credited it with giving her many lifelong friends and said she cares deeply about the people she and the community represent.

Jack Osbourne’s MS Diagnosis

Osbourne’s path to a diagnosis was long and confusing. On the “Inside of You” podcast, he recalled that about 18 months before he was diagnosed, his legs went numb for several months, and hot and cold water felt reversed against his skin.

He initially chalked it up to a pinched nerve, but when he lost vision in his right eye a year and a half later, he knew something was seriously wrong.

An eye doctor ultimately pushed him to get an MRI, worried his symptoms pointed to something more serious. At the ER, doctors initially wondered whether he’d had a stroke or an aneurysm.

“At that point, I started freaking out because I had a three‑week‑old baby,” Osbourne said.

After further testing, the real cause became clear when he was officially diagnosed with multiple sclerosis (MS).

RELATED: Understanding Multiple Sclerosis (MS): A Leading Neurologist Explains Symptoms & Diagnosis

Osbourne considers himself fortunate in the spectrum of MS experiences.

“I don’t have an aggressive form of it. I have relapsing‑remitting, and I haven’t had a flare‑up,” he said.

Understanding Multiple Sclerosis (MS)

Multiple sclerosis causes the immune system to attack cells that form the protective sheath that covers nerve fibers in the spinal cord. The disruption leads to communication problems between the brain and the rest of the body.

Once the protective barrier is damaged, the spinal cord struggles to communicate to the body’s arms, legs, and other parts to function normally.

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Better Understanding of Multiple Sclerosis

Multiple sclerosis (MS) is an “immune‑mediated condition,” meaning the immune system mistakenly attacks the body’s own tissues, explains Dr. Lauren Krupp, a neurologist at NYU Langone.

“We’re not exactly sure why that happens,” she tells SurvivorNet, “but it probably has to do with exposure to a virus at some point. In the effort to fight off that virus, the immune system turns against itself and specifically targets a coating of the nerves called myelin.”

Myelin protects nerve fibers in the central nervous system, which includes the brain and spinal cord. When it’s damaged, communication between the brain and the rest of the body becomes disrupted.

Since MS can affect different areas of the brain or spinal cord, Dr. Krupp notes, “the symptoms can vary in location.”

Common symptoms include:

• Numbness or tingling in the face
• Numbness or weakness in the arms or legs
• Vertigo or a spinning sensation
• Blurred or lost vision
• Poor coordination

Symptoms may appear on one side of the body or, when the spinal cord is involved, on both. Numbness can spread and may be accompanied by muscle weakness.

The National Institute of Neurological Disorders and Stroke describes MS as “an unpredictable disease of the central nervous system” that can range from relatively mild to significantly disabling, depending on how severely communication between the brain and body is affected. Researchers widely consider it an autoimmune disease.

There is currently no cure for MS, but many people manage the condition with medications, steroid treatments, or, in some cases, chemotherapy‑based therapies designed to calm the immune system and slow disease activity.

Common tools M.S. patients use to improve their quality of life include wheelchairs, canes, leg braces, and some medical treatments called disease-modifying therapies (DMTs).

A study in American Family Physician found that DMTs “have been shown to slow disease progression and disability; options include injectable agents, infusions, and oral medications targeting different sites in the inflammatory pathway.”

Research published in Frontiers in Neurology last year says autologous hematopoietic stem cell transplantation (AHSCT) (also called bone marrow transplantation, with autologous meaning a patient’s own cells) used for multiple sclerosis therapy helps “reset the immune system.” Several studies and clinical trials using AHSCT have shown promise.

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“In a meta-analysis of published studies using AHSCT for M.S. treatment, the pooled estimated transplant-related mortality was 2.1%, the two-year disease progression rate was 17.1%, the five-year progression rate of 23.3%, and a pooled 83% of patients had no evidence of disease activity at two years. Patients who had the most benefit and the least mortality rate were patients with relapsing-remitting M.S. (RRMS).”

Additional research published by NEJM Journal Watch says that AHSCT helps MS patients reduce relapses better than other forms of MS treatment.

The National Multiple Sclerosis Society outlines the different types of multiple sclerosis:

• Clinically isolated syndrome (CIS) is when an individual experiences a single neurological episode lasting 24 hours or less. CIS is what M.S. is diagnosed as until there is a second episode.
• Relapsing-remitting MS (RRMS): The most common M.S. among the million people battling the disease in the U.S., RRMS is marked by sudden flare-ups, new symptoms, or worsening of symptoms and cognitive function. The condition will then go into remission for some time before reemerging with no known warning signs.
• Primary progressive M.S. (PPMS): These individuals have no flare-ups or remission, just a steady decline with progressively worse symptoms and an increasing loss of cognitive and body functions.
• Secondary progressive M.S. (SPMS): This is an almost transitional form of M.S. that progresses from RRMS to PPMS.

How Multiple Sclerosis (MS) Treatment Is Improving Daily Life For Patients

For those living with multiple sclerosis (MS), advances in diagnosis and treatment are making a real difference, helping many patients achieve a better quality of life and more hopeful long-term outlooks.

Dr. Nancy Sicotte, Chair of Neurology and Director of Multiple Sclerosis and Neuroimmunology at Cedars-Sinai, tells SurvivorNet that an increasing number of patients are able to maintain stable lives due to earlier intervention and disease-modifying therapies (DMTs), medications that help slow disease progression, decrease how often and how severe relapses occur, and reduce the formation of new nerve damage.

“Now with the new diagnostic criteria, we can actually diagnose someone as having multiple sclerosis before they’ve even had a symptom, just based on the imaging. What that indicates is we could sort of, theoretically prevent clinical MS from ever appearing,” Dr. Sicotte says.

“If you can diagnose someone at that level, at that stage, put them on a disease-modifying therapy, and then they would, theoretically, never have symptoms. We would be preventing them from having any symptoms or any disability,” she adds.

Treating MS early can help prevent attacks that may cause lasting symptoms, making prevention of relapses a key goal of care.

Treatments can be injectable, oral, or infusion medications.

Understanding Disease Progression

Although researchers do not fully understand all the factors that drive MS progression, certain genetic traits appear to increase the likelihood of more aggressive disease.

Still, with earlier diagnosis and today’s effective treatments, many patients are achieving favorable long-term outcomes, Dr. Sicotte notes.

When MS is diagnosed early, patients can “get put on a very, very effective disease-modifying therapy, and then they just get on with their lives,” she explains. “I definitely have patients who I see … saying to me, ‘I really forget most of the time that I’m living with MS.’ So to me, that’s so amazing and wonderful to hear.”

Dr. Sicotte also highlights that the biggest risk for MS progression is simply age, though healthy living habits can also have an impact.

While some risk factors cannot be changed, patients can focus on healthy habits such as regular exercise, balanced nutrition, sufficient sleep, and preventing or managing chronic illnesses like diabetes and high blood pressure, Dr. Sicotte notes.

“Folks who can keep themselves relatively healthy, that seems to be protection for this progression,” she explains, adding that scientists are currently studying how aging affects the immune system and contributes to MS progression.

The research could uncover new treatment approaches not only for MS, but also for other neurological diseases such as ALS, Alzheimer’s, and Parkinson’s.

While MS is still a very serious condition, many people lead very full lives.

RELATED: Multiple Sclerosis: Dealing With Fatigue

“People with MS are just living their lives,” Dr. Sicotte says. “They’re having families, they’re working, they’re traveling, you know, they’re doing everything that they would want to do in their life. And thankfully, that is much more common these days.

“It’s very common that we see people just thrive and do well. That said, there are definitely patients who, even despite being on good treatments, will have worsening over time.”

She notes that in more advanced cases of MS, patients may experience substantial mobility limitations, with some relying on wheelchairs for daily support. A small percentage require extensive caregiving assistance.

“Our big challenge right now is better understanding why some people seem to do great and other people will have this relentless, worsening MS,” Dr. Sicotte adds, noting that a key factor is identifying MS early and starting treatment before major damage occurs.

She notes that, because aging is a major driver of progression, over time people living with MS long-term may be more likely to experience this stage of the disease.

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Finding Resources And Support

For patients and families navigating MS or another serious illness like a cancer diagnosis, gaining access to new treatment or trials can feel overwhelming. That’s why SurvivorNet encourages patients to use its proprietary Clinical Trial Finder, a free tool designed to help patients identify relevant trials quickly and easily.

Every year, new early-phase studies come online, each one representing another step forward in disease management.

SurvivorNet’s AI-powered “My Health Questions” tool was also built with patient needs in mind, to give patients and their caregivers access to health information vetted by professionals right when they need it.

WATCH: How One Cancer Survivor and Her Sister Used “My Health Questions” to Navigate Care

Contributing: SurvivorNet Staff

Learn more about SurvivorNet's rigorous medical review process.