It is related to general fluid dynamics, and it does get a bit complicated. A simple analogy is a muti storey building with one drainpipe for all the baths in the building. If everyone has a bath, then pulls the plug at the same time, the drainage capacity of the pipe is high (effect of DHT). The highest bath at the end of the system (at the top of the drain), has to drain through the same pipe, but this is being swamped by the other baths lower down. So the drainage from the top is reduced because of the restriction of increased drainage lower down. This is the simplist analogy. Really this comes down to reducing the production of DHT to reduce the restriction, and using topicals on the male pattern baldness area that reduce the formation of inflammation that increases edema. This is generaly the kind of treatment conclusion that people on these boards are reaching by experience. S Foote.