The Stages of Androgenetic Alopecia
Androgenetic alopecia is the most common form of hair loss in men and one of the most widespread in women.
Although it is often considered a consequence of aging, age actually plays a catalytic role in conjunction with two other factors: the sensitivity of the hair follicle to the hormone DHT and the degenerative effects of this hormone.
The progression of this type of hair loss is gradual. It starts from the front of the scalp and the crown, and it gradually spreads to the sides and back.
The last two regions—the sides and back—remain largely unaffected in most cases.
The progression of this condition in men is described using the stages of the Norwood scale (also known as the Hamilton-Norwood scale).
What is the Norwood Scale?
In the 1950s, James Hamilton developed a seven-stage scale to illustrate the progressive development of male hair loss.
Later, this scale was revised by O’Tar Norwood.
The resulting scale is known as the Hamilton-Norwood scale or simply the Norwood scale.
As this scale shows, the more advanced the stage, the more significant the hair loss becomes.
It should be noted that the time required to transition from one stage to the next is not fixed, as the rate of hair thinning can vary significantly from person to person.
In some cases, hair loss occurs gradually, while in others, an imperceptible thinning may persist for years and then develop rapidly, reaching the final stages of the scale within a relatively short period of time.
Why is the Norwood Scale Important?
The Norwood scale helps diagnose the degree of hair loss and determine the appropriate treatment.
There are many variations of male pattern hair loss. Below are the most typical stages:
Stage 1
This stage is characterized by minimal hair thinning that is essentially unnoticeable.
Hair thinning at this stage may be attributed to aging rather than androgenetic alopecia, which can sometimes lead to confusion.
Stage 2
This stage corresponds to slight hair loss in the frontal hairline.
Hair loss occurs in the central part of the frontal hairline with thinning in the front part of the scalp.
Stage 3
At this stage, further recession of the frontal hairline is observed, forming a pronounced M shape.
For the first time, the effects of hair thinning take on “aesthetic significance.”
There is a more noticeable recession of the frontal hairline and expansion of the areas with weakened hair growth. Hair loss also appears on the crown of the scalp.
Stage 4
At this stage, there is more advanced thinning of both the frontal hairline and the crown, with a tendency for these two areas of thinning to merge.
The thinning spreads in the front and crown of the scalp, forming a semicircle.
Stage 5
Hair thinning extends from the front and crown areas of the scalp, with the two thinning zones merging.
Stage 6
This stage is characterized by further thinning, extending to the sides and back of the scalp.
Stage 7
In the final stage, thinning spreads further to the sides and back, resulting in receding hair growth beyond the parietal (side) and occipital (back) regions.