The most common causes of hair thinning in black people include aging, tight styling and improper use of chemicals, including relaxers and dyes, according to About.com. Hair thinning that results from aging is most common in women.
Gentle styling and switching up hair styles may help counter hair thinning that results from aging, explains About.com. Tight braids and ponytails pull hairlines and damage hair follicles, causing hair loss and thinning hair. Putting chemicals on the hairlines may worsen the problem. Changing hair styles often aids in reducing tension that occurs due to tight styling. Frequent or prolonged application of hair relaxers as well as using relaxers in extremely young children or on damaged scalps may cause thinning as well.