How common is Trichotillomania?
There have been as of yet no large scale epidemiological studies of TTM, so it is difficult to obtain an accurate estimate of the prevalence of TTM. One study done in 1991 using the official diagnostic criteria noted above, estimated a lifetime prevalence rate for TTM of 0.6% for both male and female college freshmen. Once they expanded their definition to "chronic and repetitive hair pulling" and eliminated the requirement for the tension/relief cycle, the lifetime prevalence rose to 2.5% for both sexes combined (3.4% of females and 1.5% of males). Using the more realistic figure of 2.5%, the rate of occurrence of TTM is about the same as that for OCD.
The above figures would seem to suggest that TTM is more frequent in women than in men, yet that may not be the case. Men can more easily hide bald spots by shaving their beards and/or heads. Women often have more of their self-esteem wrapped up in their looks than do men and so may be more apt to be more distressed by their pulling and thus more likely to see pulling as a problem.