Androgenetic Alopecia
Androgenetic alopecia is inherited hair loss in which genetically susceptible follicles shrink in response to androgens, producing a smaller hair with each cycle. It follows a recognised pattern in each sex and continues to progress whether or not surgery is performed.
Androgenetic alopecia is inherited sensitivity, expressed over time. It is not a disease the scalp catches. Certain follicles are genetically programmed to respond to androgens by shrinking, and each cycle they run produces a smaller hair than the last. Everything visible — recession, thinning, a widening crown — is that process becoming apparent.
It is the ordinary case, not the unusual one. Roughly half of men are affected by the age of fifty, rising to around four in five by seventy; in women incidence rises markedly after menopause (Ho, Sood & Zito, Androgenetic Alopecia, StatPearls).
| Male pattern | Female pattern | |
|---|---|---|
| Where it starts | Temples and vertex | Diffuse widening at the part |
| Frontal hairline | Recedes | Usually preserved |
| Graded with | The Norwood scale | The Ludwig scale |
It is progressive, and surgery does not interrupt it. A transplant places resistant follicles among susceptible ones; the susceptible ones carry on. This is why planning is done against the pattern a person is expected to reach rather than the one they have, and why medical treatment and surgery are usually discussed together rather than as alternatives.
Not every gradual thinning is this. Diffuse shedding, thinning that includes the back of the head, and loss with visible scalp changes all point elsewhere and are worth separating before anything is planned.
Related terms
For how male pattern loss is staged, see the Norwood scale. For whether surgery is the right step, see should I get a hair transplant.
