What We Know About MS, The Condition Selma Blair Has

After making an appearance at the Vanity Fair Oscars after party holding a personalized cane, actress Selma Blair opened up about her experience with multiple sclerosis (MS) in a candid interview with Good Morning America yesterday. Blair described feeling symptoms of MS long before she was diagnosed, like immense fatigue and pain, but said she wasn't taken seriously by her doctors.

"I was ashamed, and I was doing the best I could, and I was a great mother, but it was killing me," Blair told Robin Roberts. She then added: "I was giving it everything to seem normal." Eventually, after falling down in front of her doctor, she had an MRI and was diagnosed with MS, which she shared in an Instagram post in August.

Often, MS is described as an "unpredictable disease" that affects the central nervous system, and Blair's story is one example of how complex and difficult it can be to diagnose MS. "If I can help anyone or help anyone be more empathetic to someone who might seem like me — or a lot worse, God forbid — then that's the least I can do," Blair told Good Morning America.

While it's great that Blair is drawing public attention to the realities of living with MS, there's a lot that researchers and doctors simply don't know about the disease — including the cause. So, here are answers to some common questions about MS:

MS is a chronic neurological condition that affects the central nervous system (which includes the brain and spinal cord), according to the Multiple Sclerosis Foundation. When someone has MS, immune cells cause inflammation that damages myelin, a layer of fat that allows nerve signals to transmit information. This causes scar tissue, aka "sclerosis," to develop throughout multiple areas of the central nervous system.

Due to the scope of the disease throughout the body, this can result in a number of symptoms, including: vision problems, weak muscles, tremors, problems walking or balancing, fatigue, pain, bladder control problems, sexual issues, depression, involuntary laughter or crying, and cognitive changes, according to the National Institute of Neurological Disorders and Stroke. Blair told Good Morning America that MS is often referred to as the "snowflake disease," because it presents differently in everyone.

It's tough to pinpoint exactly how many people have MS, because it takes so long to diagnose, and symptoms are often missed. (On top of that, MS isn't considered a "reportable disease," meaning health care providers aren't officially required to log cases of the disease.) A 2017 study found that about 1 million people in the United States have MS, which is double what was believed to be the prevalence of the disease.

We know that MS is two-to-three times more common in women than men, likely because hormones play a role in the disease. It's also common for symptoms to develop when women are in their 20s-40s. In the Good Morning America interview, Blair described having a MS flair-up after having her son, and that's common due to the crash in hormones that occurs postpartum. Additionally, MS may have a genetic component, especially if someone's first-degree relatives (like a parent or sibling) have MS.

Diagnosing MS is challenging, because there's not a single test that can show that someone has MS, according to the National Multiple Sclerosis Society. In order to be diagnosed with MS, people have to meet three criteria: neurological evidence of damage to two areas of the central nervous system; proof that the damage happened at different times; and ruling out of all other diseases that are similar to MS. Blood tests, MRIs, spinal taps, and evoked potential tests (which measure electrical activity in the brain) may be required to diagnose someone. Some studies suggest that people with MS may develop the disease for five years before receiving a clinical diagnosis.