Do Androgens Cause Hair Loss?

It is well known that androgen hormones contribute to some types of hair loss.  The main culprit is the androgen hormone “DHT” or dihydrotestosterone, which is made from testosterone.  There are several pieces of evidence over the last few years that support the relationship between androgens and the development of androgenetic alopecia. This relationship is more direct in men than women.

First, it was appreciated even in ancient times that castrated young men do not go on to develop androgenetic alopecia, or male pattern balding.   Later it was understood that these men maintain low testosterone levels.  It was J.B. Hamilton in the 1940s who showed that wen testosterone was given back to castrated men later years, they developed male pattern balding.  Further evidence of the role of androgen hormones in hair loss came from study a group of men in the living in the Dominican Republic. Many of these men lacked the ability to convert testosterone to the potent androgen DHT.  Interestingly, these men did not develop male pattern baldness. Finally, we now have several medications available, such as finasteride and dutasteride, which block the ability of the body to covert testosterone to DHT. These medications can halt male pattern baldness in a significant proportion of men.

Most studies have shown that men with androgenetic alopecia have similar levels of blood testosterone compared to men who are not bald.  It appears therefore that men with androgenetic alopecia inherited hair follicles that are "more sensitive" to the effects of androgens rather than simply having higher levels of testosterone.

The relationship between androgens and hair loss is more complex in women. Androgens do play a role in the development of androgenetic alopecia, but likely not to the same degree as in men. Therefore, we now appreciated that the cause of androgenetic alopecia in women is much more complex.  It is for this reason that oral anti-androgen medications are helpful in treating hair loss in women, but do not have the same profound effects as in men.