Discuss Lilskies's answer to: My daughter pulling her hair.its turned to be a habit now.we showed some phycologist too.......but......she is only 12yr old .it started before 3yr.

Trichotillomania is the medical term for a condition that describes young children and adolescents who pull out the hair from their scalp, eyelashes, eyebrows, or other parts of the body, resulting in noticeable bald patches.
It is estimated to affect one to two percent of the population, or four to eleven million Americans, and often begins in childhood and adolescence.
Although the symptoms range greatly in severity, location on the body, and response to treatment, most children with Trichotillomania pull enough hair over a long enough period of time that they have bald spots on their heads (or missing eyelashes, eyebrows, etc.) pubic, or underarm hair), 
Trichotillomania does not cause permanent hair loss, harm to the hair follicles nor does it cause brain damage. When the pulling, twisting or plucking stops, the child's hair will grow back normally. Trichotillomania is quite common in children and the behavior responds well to treatment.
The main concern for the physician diagnosing hair pulling is to rule out other problems that may be related to the hair loss. Medical conditions such as alopecia areata and tinea capitis should be ruled out. In addition, the physician will want to measure how the child is functioning, preferably from both a parent and a teacher, in order  to determine if any stress is playing a role in the child’s hair pulling.
Babies: 1 month to 2 years
Hair pulling at this age is usually a self-comforting habit. It often goes along with thumb sucking. The baby reclines with thumb or fingers in the mouth and twists his/her own or his mother's hair with the other hand. The child finds this relaxing and usually engages in the behavior before falling asleep or when he/she is distressed. Toddlers: 2 to 5 years
When a child has been pulling at their hair since infancy, the toddler will be in the habit of doing it without thinking. At around the age of three, children can tell when parents are reacting to what they do. If parents get worried or upset when their child pulls at his hair, he soon will learn how to get parental attention with this behavior. Hair pulling is used by the toddler as an effective addition to kicking and screaming during a tantrum. Younger children usually twist hair and the older ones pluck at their hair.
School age: 5 to 12 years
Trichotillomania can be a simple habit, an angry protest or a sign that a child is anxious or under stress. When a child only starts pulling their hair out at school age, there may have been other causes for the problem. It may be school-related stress or it can be an indication that something is worrying ythe youngster.