Trichotillomania - Causes and Pathophysiology

Causes and Pathophysiology

Anxiety, depression and obsessive–compulsive disorder are more frequently encountered in people with trichotillomania. Trichotillomania has a high overlap with post traumatic stress disorder, and some cases of trichotillomania may be triggered by stress. Another school of thought emphasizes hair pulling as addictive or positively reinforcing as it is associated with rising tension beforehand and relief afterward. A neurocognitive model — the notion that the basal ganglia plays a role in habit formation and that the frontal lobes are critical for normally suppressing or inhibiting such habits —sees trichotillomania as a habit disorder.

Abnormalities in the caudate nucleus are noted in OCD, but there is no evidence to support that these abnormalities can also be linked to trichotillomania. One study has shown that individuals with trichotillomania have decreased cerebellar volume. These findings suggest some differences between OCD and trichotillomania. There is a lack of structural MRI studies on trichotillomania. In several MRI studies that have been conducted, it has been found that people with trichotillomania have more gray matter in their brains than those who do not suffer from the disorder.

It is likely that multiple genes confer vulnerability to trichotillomania. One study identified mutations in the SLITRK1 gene, another identified differences in the serotonin 2A receptor genes, and mice with a mutation on the HOXB8 gene showed abnormal behaviors including hair pulling. These data are preliminary, but could indicate a genetic component in trichotillomania. The more research that surrounds this relatively newly understood phenomenon, the closer that experts come to determining whether or not it is indeed gene linked.