Dr Emin Tuncay Ustuner has written a paper in peer-reviewed journal Plastic and Reconstructive Surgery - Global Open, stating that the "force of downward pull caused by the gravity on the scalp skin" is the key contributor to the events leading to progressive hair loss in male pattern baldness.
Studies have shown that balding areas of the scalp show an increase in a potent form of testosterone called dihydrotestosterone (DHT), and there are a number of drugs that block conversion of testosterone to DHT that slow hair loss.
In the scalp, DHT seems to cause hair follicles to become thinner; however, in other areas of the body, such as the underarms and genital area, DHT and other male sex hormones promote thickening of hair follicles, raising questions as to why the hormone affects scalp hair in one way but hair in other areas in a different way.
Vicious circle
Dr Ustuner’s solution is his ‘gravity theory’ concerning the weight of the scalp on the hair follicles.
In youth, the scalp has sufficient fat tissue under the skin, and it is "capable of keeping itself well-hydrated," buffering the pressure on hair follicles.
With ageing, the skin and subcutaneous fat become thinner, and the pressure on the hair follicles increases.
Ustuner explains that testosterone contributes to thinning of the subcutaneous fat. As the cushion decreases, the hair follicle must strive against higher pressure, requiring more testosterone to achieve normal growth.
This ‘local demand’ leads to a build-up of DHT levels in the scalp, causing further erosion of the subcutaneous fat and creating a ‘vicious circle,’ according to Ustuner.
The hair growth cycle accelerates in response to DHT, but it's not enough to overcome the increased pressure. Over time, the hair follicle becomes smaller and smaller, resulting in progressively increasing hair loss.
Hair loss explained?
According to this theory, if the pressure created by the weight of the scalp is the cause of balding, then hair loss should occur at the top of the head, which the Turkish doctor claims is exactly what happens in AGA.
He believes that individual hair loss patterns are affected by differences in the shape of the head, reflecting variations in scalp pressure.
The weight of the facial soft tissue adds to the pressure at the front of the scalp, contributing to hair loss there. In contrast, the ears help resist the effects of gravity on the scalp, lessening hair loss on the sides of the head.
Scepticism
Ustuner’s ‘gravity theory’ of AGA has met with notable scepticism as it ‘simplifies’ a very complicated problem; however, the Turkish surgeon says there is no other theory that reasonably and satisfactorily explains hair loss in AGA without ascribing a function to DHT that is opposite to its known function.
He notes that, while several factors suggest that genetic factors contribute to male pattern baldness, the increase in scalp DHT levels "is not an occurrence directly determined by genes."