Androgenetic Alopecia

Androgenetic alopecia is the most common form of hair loss, affecting millions of men and women worldwide. While it can begin as early as the teenage years, this progressive condition typically becomes more noticeable with age, causing distinctive patterns of thinning and baldness that can significantly impact self-esteem and quality of life.

Table of contents

• What Is Androgenetic Alopecia?
• Alternative Names
• How Common Is This Condition?
• Hair Loss Patterns in Men and Women
• What Causes Androgenetic Alopecia?
• Associated Health Conditions
• How Is It Diagnosed?
• Treatment Options
• Emotional and Psychological Impact

What Is Androgenetic Alopecia?

Androgenetic alopecia is a common form of hair loss that affects both men and women. It is characterized by the gradual conversion of thick, pigmented terminal hairs (mature, fully developed hairs) into shorter, thinner indeterminate hairs, and finally into short, wispy, nonpigmented vellus hairs (the fine, soft hairs that cover much of the body)^[1][6]. This process is called follicular miniaturization, where the hair follicle itself shrinks and produces progressively weaker hair shafts^[5].

The condition develops slowly and can begin any time after puberty. In men, it typically starts with a gradual recession of the frontal hairline and thinning at the crown, while women usually experience diffuse thinning across the top of the head with preservation of the frontal hairline^[1][3].

Alternative Names

Male pattern baldness, female pattern hair loss, male pattern hair loss, female pattern baldness, pattern hair loss, hereditary alopecia, pattern alopecia, androgenic alopecia

How Common Is This Condition?

Androgenetic alopecia is extremely common and affects a substantial portion of the population. In the United States alone, an estimated 50 million men and 30 million women are affected by this condition^[1].

The prevalence increases significantly with age. Among men, approximately 21% in their twenties show signs of androgenetic alopecia, rising to more than 50 percent of men over age 50, and reaching about 85% by age 50 according to some studies^[1][3]. Some men may notice the early stages of male pattern baldness as early as their late teens or early twenties^[4].

In women, the condition affects about 12% between ages 20 and 30, 25% by age 49, and 30% to 40% of women aged 60 to 69^[3]. Among postmenopausal women, as many as two-thirds suffer from hair thinning or bald spots^[5]. Hair loss is most likely to become noticeable in women after menopause^[1].

The condition also shows variation among different ethnic groups. Caucasian individuals are most notably affected, followed by Asians and African Americans. Native American, First Nations, Alaska Native, and Inuit populations are less commonly affected^[2][4].

Hair Loss Patterns in Men and Women

The pattern of hair loss differs distinctly between men and women, which is why the condition is often referred to as male pattern baldness or female pattern hair loss.

In men, hair loss follows a well-defined pattern. It typically begins above both temples, with the hairline gradually moving back to form a characteristic “M” shape^[1]. Hair also thins at the top of the head, known as the vertex or crown. Over time, these areas of hair loss may connect, often progressing to partial or complete baldness^[1][3]. The Norwood Scale is commonly used to describe the various stages of hair loss in men, from Norwood 1 (no hair loss) to Norwood 7 (the most advanced hair loss that resembles a horseshoe shape)^[3].

The pattern of hair loss in women differs significantly from that in men. In women, the hair becomes thinner at the top of the head, and the middle part widens. The frontal hairline typically remains intact and does not recede as it does in men^[1][5]. Women experience diffuse thinning across the crown and top of the head, which causes a broader appearance of the part line, but androgenetic alopecia in women rarely leads to total baldness^[1][3]. Clinicians use the Ludwig Classification to describe female pattern hair loss, with Type I representing minimal thinning, Type II showing decreased volume and noticeable widening of the mid-line part, and Type III describing diffuse thinning with a see-through appearance on the top of the scalp^[5].

What Causes Androgenetic Alopecia?

Androgenetic alopecia results from a combination of genetic and hormonal factors. As the name suggests, it involves the action of hormones called androgens, which are important for normal male sexual development and have other essential functions in both sexes, including regulating hair growth and sex drive^[1][5].

The condition is primarily related to a hormone called dihydrotestosterone (DHT), which is converted from testosterone by an enzyme called 5-alpha reductase^[1][3]. In men with androgenetic alopecia, DHT concentrations are higher, and this hormone causes a change in the hair follicles on the scalp^[2]. DHT affects hair follicles in sensitive areas (usually the frontal, crown, and sometimes sides of the head), making them smaller and weaker, which leads to the miniaturization process^[3].

The condition also affects the hair growth cycle. Hair growth occurs in phases: the anagen phase (growth phase), which normally lasts 2 to 6 years, followed by a resting phase, after which the hair falls out^[1]. In androgenetic alopecia, there is a genetically determined shortening of the anagen phase and a lengthening of the time between the shedding of a hair and the start of a new growth cycle^[5]. This means it takes longer for hair to start growing back after it is shed, and the growth period itself is shorter, resulting in shorter and thinner strands of hair.

Androgenetic alopecia is a polygenic condition, meaning it involves multiple genes rather than a single gene^[2][3]. Over 190 genes have been identified as contributing to the condition, which helps explain why it affects family members to varying degrees of severity and at different ages^[9]. The condition may be inherited from either or both parents. Researchers have confirmed that variations in the AR gene, which provides instructions for making an androgen receptor, are involved in this condition^[1]. Studies suggest that these genetic changes result in androgen receptors that are more easily stimulated by androgens than normal, leading to increased activity in hair follicles^[1].

In women, the precise role of androgens is harder to determine than in men^[5]. While androgens play a role in female pattern hair loss, other factors that are not yet fully understood are also involved^[1]. The condition can also result from an underlying hormone disorder, such as overproduction of androgen or an androgen-secreting tumor on the ovary, pituitary, or adrenal gland^[5].

In addition to genetic and hormonal factors, other elements can contribute to or accelerate hair loss, including stress, obesity, smoking, alcohol consumption, diet, and certain medications^[3].

Associated Health Conditions

Androgenetic alopecia has been associated with several other medical conditions, particularly in men. These associations are important for overall health awareness.

In men, androgenetic alopecia has been linked to coronary heart disease and enlargement of the prostate. Additionally, prostate cancer, disorders of insulin resistance (such as diabetes and obesity), and high blood pressure have been related to the condition^[1]. Men with early onset androgenetic alopecia (before the age of 35) have been found to have a higher likelihood of metabolic syndrome, which includes conditions such as abdominal obesity, hypertension, and altered cholesterol levels^[7].

In women, androgenetic alopecia is associated with an increased risk of polycystic ovary syndrome (PCOS)^[1][7]. PCOS is a hormonal disorder characterized by a hormonal imbalance that can lead to irregular menstruation, acne, excess hair growth elsewhere on the body (called hirsutism), and weight gain^[1].

Researchers continue to investigate the connection between androgenetic alopecia and these medical conditions. They believe that some of these disorders may be associated with elevated androgen levels^[1].

How Is It Diagnosed?

The diagnosis of androgenetic alopecia is usually based on the patient’s medical history, the pattern of hair loss, and a physical examination. History and physical examination are the most important aspects of diagnosis^[6].

During the examination, healthcare providers look for the characteristic patterns of hair loss. In men, this includes a receding frontal hairline, thinning in the temporal areas, and hair loss at the crown. In women, providers look for diffuse thinning at the top of the head with widening of the center part while the frontal hairline is typically preserved^[1][2]. The skin on the scalp usually looks normal^[9].

A family history of similar hair loss can support the diagnosis, as genetic predisposition plays a significant role. However, family history is not always predictive because the expression of hair loss is variable^[3].

Healthcare providers may also perform a hair-pull test and use dermoscopy (a technique that allows magnified visualization of the scalp and hair) to examine the hair and scalp more closely^[2].

Laboratory tests can play a role in patient assessment, although they are not always necessary. In women, if signs of excess male hormones are evident, tests for testosterone and DHEA-sulfate may be ordered. If a thyroid disorder is suspected, thyroid hormone levels may be tested. To test for iron deficiency, which can contribute to hair loss, iron levels and related markers may be checked^[6].

A biopsy is rarely necessary to make the diagnosis of androgenetic alopecia but may be performed in clinically challenging cases^[2][6]. If a biopsy is obtained, it typically shows miniaturized hairs and may reveal a mildly increased ratio of resting-phase hairs to growing-phase hairs^[6].

Treatment Options

Although there is no cure for androgenetic alopecia, several treatment options are available to slow down the progression of hair loss, and in some cases, stimulate new hair growth. The condition tends to progress very slowly, from several years to decades, and an earlier age of onset may lead to quicker progression^[9].

FDA-Approved Medications

Only two drugs currently have FDA approval for the treatment of androgenetic alopecia: minoxidil and finasteride^[6][10].

Minoxidil is available as a topical solution or foam that is applied directly to the scalp. Although the exact method of action is not fully understood, minoxidil appears to lengthen the duration of the growth phase and may increase the blood supply to the follicle^[11]. It is marketed as a 2% or 5% solution, with the 5% solution being somewhat more effective^[11]. In general, women respond better to topical minoxidil than men^[11]. The solution or foam should be applied to the affected scalp (not the hair) and does not need to be massaged in^[9]. Regrowth is more pronounced at the crown than in the frontal areas and is not usually noted for at least 4 months, and possibly up to 12 months^[9][11]. Any benefit is only maintained for as long as the treatment is used; discontinuation produces a rapid reversion to the pretreatment pattern^[11]. Minoxidil can cause skin reactions such as dryness, redness, scaling, or itchiness at the site of application, and may cause an initial increase in hair shedding during the first 4-6 weeks of treatment^[9].

Finasteride is an oral medication available only for men. It is a 5-alpha reductase type 2 inhibitor that works by reducing levels of DHT^[9][11]. The drug can diminish the progression of androgenetic alopecia and, in many patients, has stimulated new regrowth. Continuous use for up to 14 months can be required before a benefit is usually seen^[9]. Although it affects crown balding more than frontal hair loss, the medication has been shown to increase regrowth in the frontal area as well^[11]. Decreased libido and erectile problems are recognized side-effects in approximately 2% of patients taking this treatment^[9]. Finasteride must be continued indefinitely because discontinuation results in loss of benefit within 6 to 12 months^[11]. The drug cannot be used by women because it can produce birth defects in a developing male fetus^[3][11].

Other Treatment Options

Several other treatments are available, though they may not have FDA approval specifically for androgenetic alopecia.

Low-level laser therapy (LLLT) is an FDA-approved treatment that uses light energy to stimulate hair growth^[10][13]. Devices are available for home use.

Hair transplant surgery involves transplanting hair from areas resistant to DHT (typically the back of the head) to areas affected by hair loss. This surgical procedure can produce satisfactory cosmetic results, and newer techniques like micrografting produce a more natural appearance than older methods^[3][6]. The transplanted hairs retain their resistance to DHT, a principle known as “donor dominance”^[3].

Platelet-rich plasma (PRP) therapy involves injecting a concentrated preparation of the patient’s own blood platelets into the scalp. This treatment has shown encouraging results in some studies^[10][13].

Other options being used or studied include topical finasteride, oral minoxidil (used off-label), hormonal therapies (particularly for women), microneedling, and various nutritional supplements^[10][13].

Cosmetic options such as wigs, hairpieces, hair extensions, and creative styling techniques can also be very helpful in disguising hair loss^[3][9].

Emotional and Psychological Impact

Hair loss from androgenetic alopecia doesn’t affect physical health, but it can have a significant impact on emotional well-being and quality of life. This is particularly true for women, for whom hair loss is often less socially acceptable than it is for men^[5].

The condition can severely affect self-esteem, body image, and self-confidence. People with androgenetic alopecia may experience emotional stress, anxiety, and depression^[4]. Women who lose hair can feel a loss of femininity and youth, which can have devastating psychological impacts^[3]. Female hair loss often becomes a source of distress, and many women mistakenly believe they are alone in suffering from this condition^[3].

Early recognition and treatment can help halt progression and preserve as much hair as possible, which can improve self-reported quality of life^[8]. It’s important for anyone experiencing unusual hair loss to see their primary care provider or a dermatologist to determine the cause and discuss appropriate treatment options. Healthcare providers can also provide referrals to therapists or support groups to address emotional difficulties^[5].