How do androgens cause baldness?
The male hormones involved in the mechanism of androgenetic hair loss are called androgens. The answer to the question “How do androgens cause baldness?” will need explaining in more than the space of a few lines.
There are a number of reasons behind the cause:
- Androgens act by interacting with specific receptors found on cell membranes or inside cells, as all other hormones do.
- Several forms of the androgen hormone can affect the hair follicles and different areas of the skin respond to the same androgen in various ways.
- For example, hairs located on the armpit respond to androgens by growing, whereas hairs in the scalp fall out in response to them.
Testosterone and Dihydrotestoterone
The two types of androgens involved in male pattern hair loss are testosterone and dihydrotestosterone (DHT hormone).
- The enzyme- 5-alpha reductase turns inactive testosterone into a more powerful form which is called dihydrotestosterone.
- 5-alpha reductase is the key enzyme involved in androgenetic hair loss.
- Once dihydrotestosterone is formed it has the ability to overpower any androgen molecule present on a hair follicle, leading to hair loss.
- Plain testosterone can also act on the follicles, but its effect of causing hair loss is weaker.
The impact of testosterone and dihydrotestoterone
The combination of testosterone and dihydrotestoterone, result in enduring changes to hairs covering the scalp and ends with hair loss.
- The power of these two hormones grouped together break down the hair growth cycle by making the anagen (growth) phase progressively shorter.
- The catagen (intermediate) and telogen (shedding or resting) phases remain the same resulting in an increased number of resting hair follicles within the hair growth process.
- The more hairs that enter the resting phase increase the number of shedding hairs.
- The shedding process starts with a decrease in length and fullness. Hairs grow thinner and shorter leading to brittle hairs that are prone to fall out.