Question

If obsessive-compulsive disorder (OCD) in an individual is quite debilitating and does not respond to pharmacological or behavioural treatment, surgery is an option. In some cases, patients receive implants for deep brain stimulation targeting the subthalamic nucleus. Why would stimulating the subthalamic nucleus lead to a reduction of OCD symptoms? Cite specific findings or studies to support your explanation.

Answer 1

The deep brain stimulation (DBS) of the subthalamic nucleus (STN) interrupts the disturbed information-processing using a mixture of mechanisms. This leads to the normalization of connectedness within the cortico-basal ganglia-thalamo-cortical circuits and to the reduction of OCD symptoms. Based on the strategic position of the STN within cortico-basal ganglia-thalamo-cortical circuits and its involvement in action and selection mechanisms responsible for many core OCD symptoms, the subthalamic nucleus is a mechanism-rooted target for deep brain stimulation in OCD. Thus stimulating the subthalamic nucleus would lead to a reduction of OCD symptoms.

The explanation can be seen in several studies like "DBS in the treatment of OCD by Blomstedt P, et al." and "DBS for OCD: subthalamic nucleus target" by Chabardès S et al.