Is it because of these little fellers:
Demodex Folliculorum is a common eyebrow mite that was discovered in the 1840’s. It produces an enzyme, lipase, that has been identified as a factor in thinning hair.
Demodex is believed to appear in the human scalp during adolescence and is present in most adults by middle age. Nioxin researchers found demodex in the hair follicles of people with thinning hair. The mites, found on the scalp, produce the enzyme, lipase, which can adversely affect the condition of hair.
http://www.madison-avenue.com/nioxin7.htm:scared: