It would seem that obsessive compulsive disorders (OCD) and body-focus repetitive behaviours share similar characteristics on the surface: Both involve urges to perform repetitive behaviours. But unlike compulsions experienced with OCD, body-focused repetitive behaviours are soothing and can even be pleasurable.
The pulling, picking or biting behaviour is rarely the result of specific obsessions that would characterise a compulsive disorder. This distinction is crucial because medication is a first-line treatment for OCD in the UK, but currently there is no approved medication to treat body-focused repetitive behaviours.
The critical distinction between ‘normal’ scab picking, nail biting, and hair plucking is when the behaviour does not stop, and goes on to cause significant distress, while the person feels unable to stop the actions. The causes of body-focus repetitive behaviours are poorly understood, though responses to different interventions may provide clues to the biological underpinnings.
For example, medications that target the neurotransmitter serotonin, such as Fluoxetine (Prozac), have not proven effective in reducing body-focus repetitive behaviours for most people—though medications, such as Clomipramine that act as a serotonin and norepinephrine re-uptake inhibitor, have been shown to be effective for short term treatment of trichotillomania .
This is significant as it was proposed that norepinephrine is released from Merkel cells upon mechanical stimulation to subsequently activate β2 adrenergic receptors on Merkel disc nerve endings leading to nerve impulses . It is likely it is this nerve impulse that attracts the pulling for the sensation it will give, rather than as an act of self-harm or a destructive venture.