There was a good article in the NY Times by a woman with trichotillomania. It describes the anguish some of these people suffer and it hints at adverse events that may have triggered her disorder.
"The voice my suffering has taken through the years is not a voice filled
with words, it is rather my trichotillomania, my O.C.D., the eating
disorders I survived in high school, rising from attempted suicide with
resilience as I realized on the floor of my room — I deserve better."
For more, see:
Surviving the Pain at the Roots by Alexandra Heather Foss.