A few days ago there was a post on your blog, the question was asking the effectiveness of finasteride in the time of a year, at the end of the first paragraph of your responce you talk about how effective it is in men at a young age unless they are headed for NW3 by age 23. Why is it different for men of that extreme case and what can they expect from taking finasteride? Is it pointless for them?
If there was confusion, allow me to clarify. Propecia should work better in men who are actively balding and have progressive miniaturization of their hair. The thicker the hair shafts are in the miniaturization process, the better the Propecia will work. People who have ‘twigs’ for hair (those at the end of the miniaturization process in the affected areas) or those who have completely lost their hair in the impacted pattern, are unlikely to get regrowth or thickening of the hair shafts, which is probably the way Propecia works anyway.
This drug may not work as well if you are heading to a Norwood Class 6 or 7 with existing balding areas, particularly if the miniaturization process is nearing the end of its process. For the very young man in his early 20s, advanced balding patterns are indications of an aggressive balding process and the drug may be less effective than those with mild (Class 3) balding patterns. If you lost all your hair in a Class 6 or 7 pattern or have been a Class 3 for years with little change, for example, Propecia probably will not be much benefit, because the hair is long since gone. Moreover, for reasons unknown, Propecia is reported to work best in the top/crown areas, not over the frontal areas.
It all depends upon what your rate of genetic hair loss will be and the degree of balding you may undergo. At 20 years old, it is almost impossible to determine this.