Re: Shampoo for thinning hair?
What ulyssesheart says is basically true, except that the amount of DHT does matter. As you age, your body makes more of the DHT that causes those sensitive follicles to weaken and die. A young man has those same sensitive follicles, but because his body is not producing DHT, he's keeps his hair. It's only when his body produces too much DHT that it affects the follicles.
There are some chemicals that can inhibit the amount of DHT that your body makes (e.g. Finasteride, aka Propecia). There is a non-prescription supplement called saw palmetto that some people believe performs the same function. However, I don't think anyone has ever had dramatic results with any solution. There is still no real cure for hair loss. Whoever invents one will be a billionaire.