Androgenic Alopecia

Overview

Androgenic alopecia, also known as male/female pattern baldness, is a common form of hair loss in both men and women. The condition is caused by the over-production of dihydrotestosterone (DHT), a male sex hormone. DHT causes the hair follicles to shrink, which eventually leads to the death of the hair follicles. As a result, the hair that grows back is thinner and shorter than normal. Androgenic alopecia can affect men and women of any age, but it is most common in men aged 25-40 years old and women after age 40. The condition can be treated with prescription medications or surgery, but there is no cure for androgenic alopecia.

Symptoms

People with androgenic alopecia may experience a variety of symptoms, including: hair loss on the scalp, thinning hair, a receding hairline, or bald patches. The hair loss is often gradual and may be accompanied by a sense of hair thinning or scalp tightness. In severe cases, the person may experience total baldness.

Causes

Although the root cause of androgenetic alopecia is not fully understood, it is thought to be caused by a combination of genetic and environmental factors. Research suggests that this form of hair loss is linked to hormones called androgens, specifically dihydrotestosterone. Not only are androgens vital for normal male sexual development before birth and during puberty, but they also play a role in regulating hair growth and sex drive in both genders. Hair growth starts from follicles located under the skin. The average strand of hair can last anywhere from 2 to 6 years before it falls out and the cycle begins anew with a new strands growing in its place. Excessive levels of androgens in hair follicles can result in a decreased length of the growth cycle, as well as thinner and shorter strands of hair. In addition, there is often a delay in the growth of new hairs to take the place of those that have been shed. Researchers believe that multiple genes contribute to androgenetic alopecia, but only variations in the AR gene have been backed by scientific studies. The AR gene provides instructions for creating an androgen receptor protein. Androgen receptors let the body respond properly to dihydrotestosterone and other related hormones. Although it's not fully understood how, studies show that changes to the AR gene result in more active androgen receptors in hair follicles. This activity is thought to up the risk of hair loss in men and women with a genetic predisposition.

Treatment

Minoxidil (Rogaine)

Minoxidil was originally used as a blood pressure medication, however, over time doctors noticed and unintended side effect of excess hair growth. Minoxidil was subsequently formulated into a topical form. As a topical medication it is applied to the scalp once or twice daily. It is available over-the-counter (OTC) in 2% and 5% concentrations. Minoxidil is thought to work by dilating blood vessels and encouraging hair follicles to enter the growth phase of the hair cycle. The length of time it takes to see results varies, but it is generally thought to take at least four months.

More recently, low dose oral minoxidil has been used to provide similar if not better efficacy than topical minoxidil while limiting side effects including lower blood pressure. Many patients prefer the convenience of a once daily pill.

Finasteride

Finasteride (propecia) is a prescription medication that is taken orally. It was originally formulated to treat enlarged prostate glands but, over time, doctors noticed an increase in hair growth in some of their patients. Finasteride is available in 1mg tablets and is typically taken once daily. It works by inhibiting the production of dihydrotestosterone, a hormone that is thought to play a role in androgenetic alopecia. Results vary but, in general, it is thought to take at least three months to see any benefit. Side effects of finasteride include decreased libido, erectile dysfunction, and gynecomastia.

Dutasteride

Dutasteride is very similar to finasteride and functions in a similar manner. It is available in 0.5mg capsules and is typically taken once daily. Like finasteride, it can take several months to see results. Side effects are also similar to those seen with finasteride and include decreased libido, erectile dysfunction. Dutasteride has a longer half than finasteride and blocks two types of 5-alpha reductase receptors. Studies have shown dutasteride to be more effective with a similar side effect profile to finasteride in treating androgenic alopecia.

Hair Transplantation

Hair transplantation is a surgical procedure in which hair follicles are removed from one area of the scalp and transplanted to another. This can be used to restore hair to balding or thinning areas. The most common type of hair transplant is called follicular unit transplantation. In this procedure, individual follicular units (containing 1-4 hairs) are removed from the donor area and transplanted to the recipient area. This results in a more natural appearance as opposed to the older "plug" transplantation methods.

Hair transplantation is considered a permanent solution to hair loss but, it is important to note that it does not stop the progression of androgenetic alopecia. In addition, transplantation is a expensive procedure with costs ranging from $4,000 to $15,000.

Lower level laser therapy (LLLT)

LLLT is a relatively new treatment for hair loss. It uses low levels of laser energy to stimulate hair growth. The exact mechanism by which it works is not fully understood but, it is thought to increase ATP production and cell metabolism in hair follicles. LLLT is typically administered using a hand-held device that is applied to the scalp for 20-30 minutes, three times per week. A course of treatment typically lasts 8-16 weeks. LLLT is generally considered safe with few side effects. The most common side effect is scalp irritation.

Microneedling

Microneedling is a minimally invasive procedure in which tiny needles are used to create micro-wounds in the skin. This stimulates the production of collagen and elastin, which can lead to hair growth. Microneedling is typically done with a device that contains multiple needles that are rotated to create the micro-wounds. A numbing cream is typically applied to the scalp prior to treatment. A course of treatment typically lasts 6-8 weeks. Microneedling is considered safe with few side effects. The most common side effect is scalp irritation.

PRP therapy

PRP therapy uses platelet-rich plasma (PRP) to stimulate hair growth. PRP is a concentration of platelets that contains growth factors. These growth factors are thought to promote hair growth. PRP therapy is typically done in a series of three treatments, spaced 4-6 weeks apart. A course of treatment typically lasts 12 weeks. PRP therapy is considered safe with few side effects. The most common side effect is scalp irritation.

Diagnosis

Androgenetic alopecia is often diagnosed based on a person's family and medical history, as well as a physical examination. A biopsy might be recommended if the diagnosis is not clear, however, dermoscopy (magnified hair analysis) is typically sufficient to diagnose androgenetic alopecia by identifying miniaturized hair and brown perihilar casts. These features can help distinguish androgenetic alopecia from diffuse alopecia areata, which can look similar to male pattern baldness.

Outlook/prognosis

Androgenic alopecia is often progressive. Over time, hair continues to miniaturize until it eventually disappears completely.   Some patients with androgenic alopecia may retain a few scalp hairs, while others may develop truly bald areas. Women with androgenic alopecia often show thinning of the crown rather than developing bald spots.

Androgenic alopecia can have a significant impact on patients psychologically. In addition, males with androgenic alopecia are at increased risk for actinic damage to the scalp due to exposure to ultraviolet light. Treatment options for androgenic alopecia are available, but there is no cure for this condition. Early diagnosis and treatment is important in order to minimize hair loss and preserve as much hair as possible.