Alopecia is the clinical term for hair loss. Alopecia areata (AA) refers to a condition in which hair loss fueled by your immune system’s attack on your hair follicles.

As one of many types of autoimmune diseases, AA can be lifelong, with symptoms occurring in cycles of hair loss and regrowth.

Although it’s understood that alopecia areata is an autoimmune disease, there’s no one single cause that triggers the associated hair loss in those who develop this condition.

Learn more about the possible causes and risk factors associated with AA, as well as the next steps you can consider.

Causes of Alopecia Areata

Despite what you may have heard, alopecia areata is not contagious.

Instead, alopecia areata is considered an autoimmune disease, which causes your immune system to mistakenly attack hair follicles.

There are more than 80 types of known autoimmune disorders. They all stem from your immune system mistaking healthy cells and tissues for invaders, causing it to attack.

In the case of alopecia areata, such attacks involve the hair follicles, which are normally responsible for supporting hair growth. You can think of hair follicles as anchors for your hair, which extend into either your top two layers of skin, called dermis and epidermis, to support hair growth.

When these hair follicles lose their function as from an immune system attack, this can cause hair loss and make it difficult for the follicles to support new hair growth in their place.

The number of affected hair follicles and resulting hair loss also depends on the severity of your condition, which can cause bald patches or more widespread hair loss.

Hair loss from alopecia areata occurs over a period of several weeks, and it can take several months to see regrowth.

When considering scalp hair, it may take longer. The total growth phase of new hair can last two to six years.

It's not known what causes autoimmune diseases exactly. However, experts believe autoimmune disorders like AA may develop from a combination of genetic predisposition and environmental factors, such as certain drugs or microorganisms.

It’s also thought that the genes associated with the development of alopecia areata may primarily be traced back to a gene family known as the human leukocyte antigen (HLA) complex. While the HLA complex normally helps distinguish healthy cells from invasive ones, variations in these genes could fuel an immune system’s attack on itself.

“Autoimmune conditions often travel in packs, so if you have one autoimmune disorder such as thyroid or diabetes, it is not uncommon to have others,” says Brooke Jackson, MD, a board-certified dermatologist and dermatologic surgeon based in Durham, North Carolina.

It’s also possible to develop alopecia areata before or after having another type of autoimmune disorder. These may include:

Autoimmune thyroid diseases, such as Graves’ disease and Hashimoto’s thyroiditis
Atopic dermatitis
Rheumatoid arthritis
Type 2 diabetes
Systemic lupus erythematosus
Sjogren’s syndrome
Multiple sclerosis (MS)
Addison’s disease
Celiac disease
Vitiligo

Risk Factors of Alopecia Areata

In most cases, the onset of alopecia areata–related hair loss occurs suddenly without any clear trigger. Still, in some cases, there are certain risk factors that could influence its development. If you have a genetic predisposition to AA, risk factors that could trigger the subsequent hair loss may include an injury, illness, or severe emotional stress.

“As with all autoimmune conditions, stress plays a key role in triggering the process,” explains Jackson. “When we are stressed, our immune system does not function very well and is not fully capable of protecting us.”

Besides stress and illnesses, other possible risk factors that sometimes trigger AA include hormonal changes and trauma.

Also, autoimmune disorders tend to run in families, so if you have a parent or close relative with an autoimmune disease, you may be at risk of developing one at some point, too. Having a parent with alopecia areata doesn’t automatically mean you’ll develop this autoimmune disorder.

But the American Academy of Dermatology Association estimates that at least 10 to 20 percent of people with AA have close blood relatives with this condition, too.

It’s also possible to develop alopecia areata at any age. Age itself isn’t considered a risk factor for this autoimmune disease, but alopecia areata most commonly develops during childhood or early adulthood.

Also, adults who develop areata alopecia after the age of 30 are less likely to have a family member with this disease. Gender is not a risk factor for alopecia areata; the condition is estimated to affect both women and men in equal numbers.

More research needs to be done to understand race as a possible contributor to alopecia areata development, but it’s thought that this condition is more prevalent in Black and Hispanic Americans compared with non-Hispanic white Americans.

Another potential area of study is the role of low vitamin D serum levels and the development of autoimmune diseases like alopecia areata. There’s not enough research to link vitamin D deficiency with AA, but experts note that people who have autoimmune disorders tend to have low vitamin D.

Can Alopecia Areata Be Prevented?

There’s currently no cure for alopecia areata, and like other autoimmune diseases, it can’t be prevented. However, with treatment, you may be able to see hair regrowth.

If alopecia areata or other autoimmune diseases run in your family, it may be worth considering discussing these with your doctor. Although autoimmune diseases can’t necessarily be prevented, your doctor may order bloodwork and other diagnostic tests that could help diagnose and potentially treat any immune-related disorders as early as possible.

Summary

Alopecia areata is an autoimmune disorder that causes hair loss due to your immune system’s attack on hair follicles that support normal hair growth. It’s not clear what exactly triggers this disease, but it’s thought to be attributed to a combination of genetic and environmental factors.

Regardless of the exact cause or trigger of alopecia areata, it’s important to see a dermatologist — they can help properly diagnose this condition and offer the best treatment methods possible to promote hair regrowth.

“Treatments are dependent upon several factors: severity, age of the patient, and other associated conditions,” Jackson notes. “The treatment plan is an extensive conversation and is best determined with the dermatologist who is treating the patient.”