Diffuse patterned alopecia (DPA) is a type of hair loss that does not progress to the point of complete baldness in any given area of the scalp, but rather introduces a general overall thinning of the hairs. With DPA, the hairline does not recede, but everywhere else becomes thin with the exception of the donor zone, a strip of hair on the occipital scalp that is resistant to Dihydrotestosterone, the male hormone responsible for causing genetic baldness.
With DPA, the hair will thin in a pattern similar to male pattern hair loss (MPH). In fact, the pattern of hair thinning will match the Norwood/Hamilton hair loss chart, a series of illustrations that depicts the most common stages of MPH. However, the difference is that the hair is not lost, but rather thins enough that the underlying scalp becomes visible.
DPA is considered a form of androgenic alopecia, meaning that the hair loss is caused by an androgen (male sex hormone). In this case, the culprit for hair loss is Dihydrotestosterone (DHT), a byproduct of testosterone after it becomes metabolized with an enzyme called 5 alpha-reductase.
DHT gathers in the scalp’s tissues, where it may negatively impact the hair follicle only if the individual has a genetic sensitivity to the DHT hormone. Not all people are susceptible to DHT, but if such sensitivity is present, then DHT prevents the hair follicle from receiving nutrients by interfering with its pathways to the blood supply. This lack of blood flow causes the follicles to shrink (also known as “miniaturization”). With DPA, instead of ceasing to grow, new hairs emerge thin and brittle.
DPA is genetic, meaning that there is no predetermined age. DPA can begin to manifest itself at any age, but since it is caused by a male sex hormone, it is much more apparent in adult men than women. Women have DHT in their bodies, but their genetic makeup makes them less prone to the damaging effects of DHT on hair follicles. Women are much more likely to develop diffuse unpattern alopecia (DUPA), which is characterized by a thinning of hair even in the donor zone itself.
The severity of DPA can be reduced by taking hair-stimulating medications such as Finasteride and Minoxidil. Finasteride prevents the 5 alpha-reductase from metabolizing testosterone into DHT, which can slow down or even halt the DPA process. Minoxidil widens the hair follicle (thickening the hair), and causes the hair follicle to enter longer stages of anagen (the growth phase), which affords a longer time frame of active grow.
In addition, those affected by DPA often respond well to conventional transplant procedures. Unlike diffuse unpatterned alopecia (DUPA), the donor zone in those with DPA is still largely intact, and may be use for transplantation. For this reason, DPA patients are viable candidates for follicular unit extraction (FUE) and follicular unit strip surgery (FUSS).