@MaxVerstappen
Male pattern baldness/hair loss and androgenic alopecia are terms used interchangeably, but they not the same thing. The former refers to the way men lose their hair. The latter is the theory that MPB is caused by androgens.
I say theory because it's not obviously true. Why are babies (of both sexes) born with "androgenic alopecia?" Clearly, babies have not lost their hair due to "DHT miniaturizing the hair follicle." In fact, it grows back.
If you want to propose some theory as to why hair loss occurs, it needs to answer:
- Why are babies born with "male pattern baldness,"
- Why do men start losing their hair in early adulthood, and
- Why do men continue to lose their hair as they age (while androgens fall off).
Preferably, you should also have answers for why finasteride works, why mothers that lose hair post-partum, and why said mothers regrow their hair.
The "androgenic alopecia" theory is obviously attractive because men have androgens and women . But "cumulative exposure to androgens" is a flimsy just-so for 3, and there is nothing to explain newborn hair loss.
I don't have the answers, but I do have a few observations:
- Hair follicles are different from most organs in that they constantly cycle between phases of growth and differentiation. Understanding the difficulty of this task and the factors involved is critical to solving this puzzle.
- It would be very surprising if the hormones involved in controlling growth vs. differentiation in gestation didn't play a role in growing hair follicles.
- Both newborns and post-partum mothers have a lot of progesterone. Could it be that progesterone is enabling the regrowth of hair? Something must be doing that, or at least preventing the hair loss from becoming permanent.
- Tissue growth is an energy-intensive process. Both pregnenolone and progesterone stabilize energy production.
- Young people have a lot of the basic steroid pregnenolone. Pregnenolone production declines steadily with age.
- During puberty, the sex-differentiating steroidogenic enzymes get turned. The relative levels of pregnenolone go down for both sexes, but women get progesterone whereas men get testosterone.
- Finasteride is very similar to progesterone.
Finasteride:
Progesterone:
It seems to me that women keep their hair because of progesterone, rather than men lose their hair because of androgens.