By now, you've probably read about (or seen video of) Will Smith slapping Chris Rock after Rock made a joke directed at Smith's wife, Jada Pinkett Smith. The joke in question referenced the lack of hair on Pinkett Smith's head, which she has publicly explained is a result of alopecia, as described in an Instagram post from December.

Alopecia is another name for hair loss. Despite being extremely common, losing hair can impact the mood and well-being of those who experience it because of the way hair is so closely tied to personality and identity. 

There are different types of alopecia, which have different causes and can present differently. It can occur anywhere on the body, but it's most talked about when it causes hair loss on the scalp.

In addition to Pinkett Smith, other public figures have opened up about having alopecia and advocated for greater awareness and acceptance, including Massachusetts Rep. Ayanna Pressley and actress Viola Davis. 

While hair loss from alopecia can be permanent for some people, new research published in The New England Journal of Medicine could one day offer options for those with severe alopecia areata, which is hair loss caused by an autoimmune response. In the trial, one in three participants with alopecia areata regrew hair at 36 weeks after taking daily doses of baricitinib, a drug that's used to treat other conditions including arthritis. (It's also been used to treat COVID-19, in some cases.) 

Clinical trials are ongoing to assess the long-term effectiveness and safety of the drug, according to a Yale Medicine press release. But the trials are often the "final testing hurdle" before a drug is considered for approval by the US Food and Drug Administration.

Here's what to know about alopecia.

What is alopecia? What causes it?

There are a few different types of alopecia. Genetics predisposes a person to developing certain types of hair loss, but environmental factors can play a role, too. Hair loss can happen suddenly, and be temporary or permanent.

Alopecia areata 

This type of hair loss is caused by an autoimmune condition in which the hair follicle attacks itself, leading to hair loss that can be permanent or temporary. It tends to be unpredictable, according to the American Academy of Dermatology, and many people with this condition develop it when they're younger or in their teens, but it can affect older adults, too.

According to the National Alopecia Areata Foundation, it affects as many as 6.8 million Americans, or a little more than 2% of people, at some point. 

Although it's an autoimmune condition, people with alopecia areata are typically otherwise healthy, according to the AAD. Like other types of hair loss, there is a genetic component to alopecia areata, but environmental factors play a role, too, per the NAAF.

Androgenetic alopecia 

Also called male- or female-pattern hair loss, androgenetic alopecia is one of the most common types of hair loss. Balding is often associated with men, particularly as they get older, but this is a common type of hair loss for women, too. 

According to the National Library of Medicine, it affects more than 50% of men by age 50, and is also common in women after they reach menopause, though it presents a little differently. In men, androgenetic alopecia typically causes the hairline to recede gradually, starting from the front of the hairline. In women, hair gradually thins all over the scalp, but rarely leads to total hair loss. 

Androgenetic alopecia can be genetic, as the name suggests, and having a family member with this type of hair loss may make it more likely you'll develop it, too. It's also caused by certain hormones (androgens) that are higher in men and post-menopausal women.

People with this type of hair loss may be at higher risk of polycystic ovary syndrome (PCOS), coronary heart disease and prostate enlargement, according to the National Library of Medicine.

Central centrifugal cicatricial alopecia

This is a pattern of hair loss in the center (crown) or your scalp. In people with this condition, the hair follicles can become destroyed, cause scar tissue and lead to permanent hair loss, according to the AAD. Because it can be permanent, it's important to seek treatment. For CCCA, that means prescription medication. 

This type of hair loss is most common in Black women, but can occur in men and people of all races.

Stress or illness-based hair loss

Anagen effluvium is a type of hair loss brought on by medical treatment such as chemotherapy. Telogen effluvium is hair loss brought on by stress, illness or even a hormonal shift such as pregnancy. But both conditions have to do with interference of the hair's growth cycle, which can return to normal once the stressful event or treatment subsides.

Traction alopecia is another type of hair loss that results from prolonged tension on the scalp, such as wearing tight ponytails or braids. It can also cause itching, redness or other symptoms. It can be reversible, but your doctor may prescribe antibiotics or other medication to treat the scalp.

Is there a cure for alopecia?

There are many treatments available for hair loss, though it depends on the type. 

Alopecia areata may respond to treatment with steroids, which interfere with the immune system cells, according to Yale Health. The recent clinical trial results published in The New England Journal of Medicine were on baricitinib, which is an inhibitor that disrupts communication between immune cells. However, these treatments may not work for everyone, and it can depend on the severity of the disease. Some people have also used phototherapy, or light therapies, and some mild cases may resolve themselves.

Androgenetic alopecia may be treated with the medication Minoxidil (Rogaine), which is effective for both men and women, according to Harvard Health. In some studies on hair growth with this type of alopecia, essential rosemary oil was just as effective as Rogaine, according to Healthline.

Bottom line? Talk to your doctor or health care provider if you're experiencing hair loss that's out of the ordinary. Even if you decide to rock your new look au naturel, it's important to get examined by a professional to determine what's causing the hair loss and determine best steps moving forward.

The information contained in this article is for educational and informational purposes only and is not intended as health or medical advice. Always consult a physician or other qualified health provider regarding any questions you may have about a medical condition or health objectives.