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LibraryHair Loss ConditionsWhat is Androgenetic Alopecia?
Last updated    | 8 minute read
Young brunette man photographed from above touching his scalp with both hands. A small bald spot has developed in the centre of his head that is characteristic of androgenetic alopecia.

What is androgenetic alopecia?

Written by
XYON Medical Team
Clinically reviewed by
Dr. C. Han, MD, FRCPC
Dr. S. Pimstone, MD, PhD, FRCPC
Dr. V. Hasson, MD

For many men, having great hair is an instant confidence boost. But for some, androgenetic alopecia (also known as male pattern baldness) can put a damper on things. It’s a common and progressive hair loss condition that can lead to drastic changes in the appearance of hair if left untreated.

In this article, we break down exactly what androgenetic alopecia is, the latest theories about what causes it and how to treat it. Making hair loss a thing of the past begins with having the right information.

What is androgenetic alopecia?

Androgenetic alopecia (AGA) is a form of hereditary and hormonal hair loss that results in balding along the hairline, temples and at the top of the head. It can start anytime after puberty and affects approximately 50% of men by the age of 50, with a higher incidence among Caucasian men (Ho et al., 2020).

The specific hormone implicated in AGA is dihydrotestosterone (DHT), which is related to testosterone. Together, testosterone and DHT belong to a class of hormones called androgens.

While DHT is present throughout the body and serves key functions in biological males, increased sensitivity of hair follicles to DHT can trigger the development of AGA in genetically predisposed individuals (Rossi et al., 2016). These genetic differences cause scalp tissues to respond to, produce and metabolize DHT differently.

What causes androgenetic alopecia?

A primary cause of male pattern hair loss is increased activity of DHT. When DHT attaches to its hormone receptor on hair follicles in the scalp, a process called follicular miniaturization is triggered.

Follicular miniaturization
Follicular miniaturization is a gradual process that involves changes to the timing of the hair growth cycle and shrinking of the hair follicle. These changes are thought to occur during the transition periods between phases of the growth cycle.

The mechanisms responsible for miniaturization are still being studied, but one theory is that the attachment of DHT triggers premature cell death (Cranwell & Sinclair, 2016). When the cells of the dermal papilla region (How does hair grow?) of the hair follicle are affected, the follicle may not regenerate properly.

Miniaturized hairs also have a distinctive appearance. They are referred to as vellus hairs and are often shorter, finer and lighter in colour. In advanced AGA, hairs may become too fragile or short to break the surface of the scalp, leading to the appearance of bald spots (Rathnayake & Sinclair, 2010).

Miniaturization may progress to the point where hairs lose contact with the skin structures that hold them in place. When this occurs, hairs fall out leaving behind empty follicles (Cranwell & Sinclair, 2016). At this stage, follicles are said to be dormant and hair loss is very difficult, if not impossible to reverse. This is one of the reasons why timely and consistent treatment of AGA is so critical.

Microinflammation of the hair follicle
In addition to hormones, researchers have also looked at other factors that may contribute to male pattern baldness. One proposed mechanism is microinflammation, or localized, long-term inflammation of the hair follicle.

Inflammation is one aspect of the body’s overall immune response and can be triggered by environmental, biological or physical factors such as:

  • toxins produced by the overgrowth of bacteria naturally present on the scalp
  • excessive sun exposure, which causes cells to produce reactive oxygen species, or byproducts of cell metabolism capable of causing damage to building blocks of cells (Rossi et al., 2016).

These agents prompt the body to release molecules that coordinate an inflammatory response. Some of these molecules have been associated with premature cell death (apoptosis), leading some scientists to speculate that inflammation could play a role in follicular miniaturization.

How to treat male pattern hair loss

There are a number of options when it comes to treating AGA. They vary in their effectiveness and some have important safety considerations. These include: 5-alpha reductase inhibitors (5-ARIs or DHT blockers), hair growth stimulants, minimally-invasive procedures and non-pharmacological alternatives such as hair care products and dietary supplements.

Depending on the severity of your hair loss, it may not be reversible. But action can still be taken to slow or halt its progression. We recommend talking to a physician to identify the best course of treatment for your specific case of hair loss.

1. 5-alpha reductase inhibitors (5-ARIs) and DHT blockers
5-alpha-reductase inhibitors (also referred to as DHT blockers) are a class of medications that target the 5-alpha reductase (5-AR) enzyme which converts testosterone to DHT. Examples include the FDA-approved finasteride (1 mg oral/daily) and newer dutasteride, which is currently undergoing clinical trials. By binding to 5-AR and preventing DHT synthesis, blood and scalp levels of DHT are reduced.

Reduced scalp DHT levels have been associated with hair regrowth and delayed follicular miniaturization in individuals with AGA (Cranwell & Sinclair, 2016). However, because 5-AR and DHT are involved in other biological reactions, decreased levels of this enzyme and hormone have been linked to sexual and psychiatric side effects in some men. In most cases, these side effects are minor and transient. They usually resolve once the medication is discontinued or with continued use.

It is important to know that women of childbearing potential should not use and avoid exposure to finasteride in any form. This is due to the medication’s effects on male sex steroid hormone levels and potential to harm a developing male fetus.

Topical Finasteride, with SiloxysSystem™ Gel is a compounded preparation of finasteride. It must be prescribed by a physician and can only be obtained from a compounding pharmacy. Topical forms of finasteride are generally associated with a lower risk of side effects.

2. Hair growth stimulants
The purpose of hair growth stimulants is to increase vasodilation (blood flow) in the scalp and support the development of hair cells. Although the exact ways in which these agents work are still being investigated, some researchers theorize that hair growth stimulants are involved in biochemical signaling important to cell growth (Rathnayake & Sinclair, 2010).

Arguably, the most well-known medication in this category is minoxidil, which is available over-the-counter as a topical solution or foam. It has been approved by the FDA for the treatment of AGA in men and women at a concentration of either 2% or 5%. It may help push hair follicles in the rest phase of the hair growth cycle into the active growth phase early (Badri et al., 2021).

Unlike finasteride, minoxidil does not affect the production of DHT, so it cannot stop follicular miniaturization. Because of this, it should not be thought of as a long-term treatment for AGA.

In addition, depending on the formulation, certain ingredients added to enhance absorption of minoxidil may cause skin irritation. Minoxidil may also trigger excess hair growth outside of the scalp and has been shown in laboratory studies to potentially have an effect on the structural integrity of collagen, an important skin protein (Messenger & Rundegren, 2004).

3. Minimally-invasive treatments
Minimally-invasive treatments for AGA include hair transplantation and platelet-rich plasma (PRP) therapy.

Hair transplantation may be an option if pharmacological treatment alone is not sufficient to treat your hair loss. Hair transplantation involves surgically removing hair follicles that are more resistant to miniaturization and re-inserting them into areas of the scalp that have been affected by AGA (Rathnayake & Sinclair, 2010). Over time the procedure can help restore the look of fuller, thicker hair.

PRP is an experimental therapy that involves delivering microinjections of a concentrated plasma solution into the scalp. Plasma is a component of blood which is rich in proteins and other molecules involved in wound healing and tissue regrowth.

Once introduced into the scalp, these growth agents are thought to target stem cells of the bulge region of the hair follicle and help signal hair growth and follicle regeneration. PRP may also promote blood vessel formation (Rossi et al., 2016). However, it is a costly treatment and there is currently a lack of conclusive clinical evidence for its efficacy in treating AGA.

4. Natural ingredients that stimulate hair growth
Increasingly, plant-derived ingredients are being explored for their anti-androgenic, antioxidant and anti-inflammatory properties. Examples of these agents include: saw palmetto extract, pea sprout extract, rosemary oil and ginseng. Many have been studied in small-scale clinical trials and could be beneficial to hair growth. They’re often incorporated into hair care or styling products or taken as supplements.

Additional data is needed to standardize formulations and establish clinical efficacy of these natural alternatives. When used alone, they may not be sufficient to treat or prevent AGA.

The takeaway

AGA affects millions of people worldwide. It is a treatable condition and individuals usually respond well to therapy, provided hair loss is identified and treated early.

Being proactive about AGA is not just a matter of saving your hair. At XYON, we understand the potential impact of hair loss on all aspects of your life. If you know that you have a family history of balding or have started to notice thinning hair or unusual shedding, consider talking to a physician to determine if treatment may be necessary.


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