What causes alopecia? Here's what you need to know about its causes, symptoms and treatment

Viewers around the world were shocked on Sunday when Will Smith slapped Chris Rock at the Academy Awards after Rock made a joke about Jada Pinkett Smith’s hair.

Rock had joked about a “G.I. Jane” sequel, referring to Pinkett Smith’s bald head. Actress Demi Moore appeared in the 1997 movie with a shaved head.

Pinkett Smith was seen rolling her eyes at the joke on Sunday before her husband, Smith, walked up to the stage, slapped Rock and yelled “Keep my wife's name out of your (expletive) mouth.”

The moment came after Pinkett Smith in 2018 confirmed she was diagnosed with alopecia, and the actress and “Red Table Talk” host has been open about her experience with hair loss.

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But what is alopecia? How can it affect your hair, and are there any treatments for it? Here’s what you need to know:

What has Jada Pinkett Smith said about her alopecia?

In a 2018 episode of “Red Table Talk,” Pinkett Smith told viewers that she was “having issues with hair loss” and that “it was terrifying when it first started.”

“I was in the shower one day, and then just handfuls of hair just in my hands, and I was just like, ‘Oh my God, am I going bald?’” she said. “It was one of those times in my life where I was literally shaking with fear.”

At the time, Pinkett Smith said, she had “every kind of test” and wasn’t certain about why she was losing hair.

“People said stress. People say, ‘Oh, you have, you do have alopecia,’” she said.

Since then, Pinkett Smith has continued discussing the condition. She shared a video on Instagram last year of a line that appeared in the short hair on her head, writing in the caption, “Me and this alopecia are going to be friends.”

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What is alopecia?

Alopecia is a medical term for hair loss, which can include everything from common balding on the head to hair loss on the body and more, according to the Mayo Clinic. Alopecia areata is a disease in which the immune system attacks hair follicles, causing hair loss

There are multiple kinds of alopecia areata, which can include:

• Patchy alopecia areata, which causes hair loss in coin-sized patches.

• Alopecia totalis, which causes people to lose all or nearly all of the hair on the top of their head.

• Alopecia universalis, in which people lose all or almost all of the hair on their scalps and the rest of their bodies.

Alopecia is not deadly. Most people with alopecia areata are healthy and do not have other symptoms, according to the National Institutes of Health.

What causes alopecia?

Many factors can cause hair loss, including genetic history, hormonal changes and medical conditions such as alopecia areata, according to the Mayo Clinic.

Hair loss can also happen after taking certain medications and supplements. Certain hairstyles and treatments that pull on your hair can cause a condition called traction alopecia.

While all people can experience hair loss, a 2018 study found that Black and Hispanic women in the U.S. have an increased risk of alopecia areata compared with non-Hispanic white women.

Can stress cause alopecia?

People can experience thinning of their hair several months after a “physical or emotional shock,” according to the Mayo Clinic.

The Cleveland Clinic noted that many people experiencing the onset of alopecia areata have had recent sources of stress, although the link has not been proven through large trials. Emotional stress can bring alopecia in people at risk for the condition, The Wall Street Journal reported.

Doctors told The New York Times patients recovering from COVID-19 have reported hair loss, which is not a symptom of the virus but a symptom of the stress from recovering. Others who never tested positive for the coronavirus also reported losing hair from stressors like deaths of a family member, job loss and more, though they may not be diagnosed with a specific form of alopecia.

Does alopecia cause permanent hair loss?

It can, but many people with conditions related to alopecia do see their hair regrow. Hormonal changes, such as those during pregnancy or menopause, and medical conditions can cause both permanent and temporary hair loss, according to the Mayo Clinic.

For those with alopecia areata, hair more commonly regrows on its own in people with less extensive hair loss, people who saw an onset of alopecia at a later age, and those without a family history of the disease.

How is alopecia treated?

Treatments for different kinds of alopecia can include medicines that help with hair growth, hair transplants and more. When treating alopecia areata, a person may use corticosteroid injections, according to Johns Hopkins Medicine.

Treatment for different kinds of alopecia and baldness depends on the underlying cause of the hair loss, but most forms of baldness don’t have a cure.

What other celebrities have alopecia?

Yes, actors, lawmakers and other public figures have spoken out about their experience being diagnosed with alopecia, such as:

• Actor Anthony Carrigan, who told Buzzfeed he has had alopecia since he was 3.

• Actor Viola Davis, who lost half her hair when she was 28 due to alopecia areata, Vulture reported.

• U.S. Rep. Ayanna Pressley, D-Massachusetts, who in 2020 told The Root she is "making peace with having alopecia."

This article originally appeared on USA TODAY: Jada Pinkett Smith has been open about alopecia. What are its causes?