As men age, hair loss becomes increasingly common. Studies have reported that 30 to 50% of men under age 50 have already begun to experience male pattern hair loss, and the risk continues to go up with each passing decade. Studies in some populations have found that up to 96% of men will eventually experience hair loss. This condition is more common in Caucasian men, but men from any racial group can experience male pattern balding.
Male pattern baldness is medically known as androgenetic alopecia, or AGA. (AGA can also occur in women, although the pattern of hair loss is different; this is known as female pattern baldness.) The specific pattern of hair loss that occurs in male pattern balding can vary somewhat. In general, the hairline will recede and the crown of the head will develop a bald
spot, although the specific order can vary between men. In the most advanced stage, there will be only a strip of hair remaining near the ears and around the bottom part of the scalp.
It’s believed that AGA in men is caused by a variety of factors. Research has established that a particular form of testosterone called DHT is involved. This hormone affects the hair follicles, causing them to shrink and to spend more time in the resting phase. There are higher levels of DHT in bald areas of the scalp, and medications that decrease DHT levels (such as finasteride) are effective for treating male pattern balding.
Although DHT is known to be important in causing AGA, other factors are also important. Studies also indicate that genetic influences explain 80% of a man’s risk of experiencing hair loss. There may be additional environmental influences that also increase the risk, although more research is needed in this area.
Although male pattern hair loss is not life-threatening, it does raise the risk of skin cancer on the scalp. Diligent sun protection will help to reduce this risk. In addition, this condition can have serious impacts on a man’s self-esteem and confidence, and may increase the risk of depression. The psychological impact tends to be greatest in those who begin losing their hair while they’re younger. Most men manage to cope with hair loss, but it’s important to recognize that this condition can cause significant distress.
In general, AGA follows one of a few predictable patterns in men:
● Bitemporal regression, in which hair is first lost above the temples on both sides, creating an “M” shape to the hairline. This is the most typical pattern of AGA in men.
● Vertex hair loss, in which a spot of hair is lost at the crown of the head, and this spot slowly expands. Usually, this occurs after some bitemporal regression has already begun. In some men, this phase begins earlier, while in others, hair isn’t lost at the crown of the head until after the hairline has significantly receded.
● Frontal hair loss, in which the hair above the forehead gradually becomes thinner until it’s lost. Later, hair is lost from the crown of the head. This is a less typical pattern than bitemporal regression, but is experienced by some men. With all of these types, male pattern hair loss is typically symmetrical, meaning that it’s the same on the left and right sides of the head. The hair loss is also progressive, meaning that it will gradually get worse over time.
The Hamilton-Norwood scale (sometimes simply called the Norwood scale) is the most common method used to describe how advanced a man’s hair loss is. There are seven stages, with stage 1 being early hair loss and stage 7 being the most advanced. There are some variations on stages 2 through 5, based on which of the specific patterns of hair loss a man is experiencing.
In the advanced stages, male pattern hair loss generally results in the loss of most or all of the hair from the top and sides of the head, leaving just some hair around the ear and a strip of hair around the bottom part of the scalp. It’s rare that AGA will cause a man to lose absolutely all of his hair; there will usually be a little hair remaining, even in the most advanced stages. Other causes of hair loss may result in different patterns. For example, alopecia areata is an autoimmune condition that causes patchy hair loss, which can occur on any part of the scalp. Low thyroid hormone levels can cause diffuse hair loss across the entire scalp. A professional medical evaluation can determine whether a man is experiencing male pattern balding, or whether he may have a medical condition causing (or contributing to) his hair loss.
Although AGA is extremely common, researchers are still working to discover all of the mechanisms involved in causing male pattern hair loss. This condition appears to be caused by a combination of a few different factors. Hormones are very important, with genetics also playing a major role in determining whether and when a man will experience male pattern hair loss. Environmental causes, like stress and unhealthy lifestyle choices, may also play a role.
AGA occurs due to the actions of dihydrotestosterone, or DHT. This is the most potent form of testosterone. An enzyme called 5α reductase acts to convert testosterone into DHT. This enzyme is found in various parts of the skin and scalp, including both oil glands and hair follicles. In areas of the scalp that are balding due to AGA, 5α-reductase activity and DHT levels are increased, compared with other areas that still retain their hair.
When DHT acts on hair follicles in the scalp, it causes a phenomenon known as miniaturization. This means that the hair follicle becomes much smaller, so the hair that grows from it becomes much thinner. As a result, the hair becomes more difficult to see, like the “peach fuzz” hair on more delicate areas of the skin. The area therefore appears bald.
In addition, DHT causes hair follicles to spend a longer time in the resting phase and a shorter time in the growing phase. Because of this, there are fewer hairs growing on the scalp at any given time. The hairs may grow for only a short time before they fall out; in the advanced stages, they may barely even grow above the surface of the skin before the growth phase ends.
When DHT acts on hair follicles on the face and body, it causes the hairs to become thicker and darker. It’s still not known why DHT seems to have the opposite action on the hairs on certain parts of the scalp. Researchers are still working to understand why this may be.
The effects of DHT on hair follicles don’t cause any scarring. In fact, these effects have been
found to be reversible, at least to some degree. Treatment with a medication that reduces 5α-reductase activity and decreases DHT levels, such as finasteride or dutasteride, can stop or even reverse hair loss in many men.
Some men begin to experience balding at younger ages, while others don’t experience it until they’re much older, and a small percentage of men never lose their hair. This is not necessarily related to different testosterone or DHT levels, but rather reflects the sensitivity of a man’s hair follicles to DHT. This is largely determined by genetics – some men’s hair follicles are much more sensitive to DHT, and they tend to start losing their hair at younger ages as a result.
Research has established that genetics explains about 80% of a man’s risk of AGA. While it’s clear that there are strong genetic influences on a man’s likelihood of experiencing male pattern baldness, it’s still not entirely clear which specific genes are involved.
Studies have discovered 12 different genetic regions that may contribute to the risk of male pattern baldness. The gene coding for the androgen receptor seems to be important; DHT and other androgens (like testosterone) must bind to this receptor in order to act on tissues. Several other genes that may contribute to the risk of AGA are involved in the signaling pathways that DHT activates in hair follicles, or regulate these effects. However, we still need a lot more research in this area, and we don’t yet have a genetic test to determine a particular man’s risk of male pattern baldness.
The action of androgens is definitely an important factor in androgenic alopecia, and genetics have an effect as well. However, recent research indicates that there may also be other contributing factors, including environmental factors.
In fact, prostate cancer, heart disease, diabetes, obesity, and high blood pressure have all been associated with AGA. This could indicate that these conditions actually raise the risk of male pattern baldness, perhaps by increasing stress on the body. However, another explanation is that stresses in the environment accelerate hair loss and also lead to these serious health conditions.
One environmental factor that seems to be important is a chemical process known as oxidative stress. When cells use oxygen for energy, compounds called free radicals are formed. These free radicals cause damage to structures in the cell. Antioxidants are compounds that help to protect the cell from free radicals. Many antioxidants are found in fruits and vegetables, which is one reason that these foods are important in a healthy diet.
When cells are unable to protect themselves from free radicals, this creates oxidative stress. Chronic psychological stress (such as from work), an unhealthy diet, chronic diseases, and the aging process itself can all make it more difficult for the body to neutralize free radicals, leading to increased oxidative stress. Additional free radicals are formed from environmental pollutants, smoke, and even UV light from the sun.
Oxidative stress causes damage to hair follicles at the cellular level, which triggers inflammation. Some researchers believe that this is a major contributor to male pattern hair loss. Because oxidative stress is also related to other serious health conditions, this would explain
why men with AGA may be more likely to experience health problems as well.
People with inflammatory skin conditions like psoriasis and seborrhea (dandruff) may also experience inflammation in and around the hair follicles, and may experience hair loss as a result. Although this type of hair loss is not the same as AGA, it does demonstrate that
inflammation can affect the hair follicles and cause hair loss.
There are two FDA-approved prescription treatments, which have been shown to be effective for AGA. Finasteride is a medication that alters DHT levels and is approved for use only in men, while minoxidil acts on the hair follicle itself and is approved in both men and women. In addition to the prescription treatments, there are other options that have been shown to be effective, such as topical caffeine and melatonin.
Each treatment option has its own potential side effects to consider, and different treatments will work best in different people. If you’d like to explore your options for treating male pattern baldness, it’s best to consult with a qualified dermatologist, who has expertise in treating hair loss. This will give you access to prescription options if you choose that route, and you’ll get professional advice that will help you to feel confident in deciding what treatment plan is right for you.
