Current status of deep brain stimulation

Deep brain stimulation (DBS) is the most focal method for stimulation of the human brain. It has been established as a useful adjunct therapy for severe, medication-refractory movement disorders, and it remains an investigational treatment for other neurological conditions as well as in neuropsychiatry. In movement disorders, DBS targets are based on those of earlier lesion procedures and on knowledge of anatomical networks thought to be involved in illness pathophysiology. In contrast to earlier techniques, DBS is nonablative, offering the advantages over previously available neurosurgical treatments of reversibility and adjustability. The adjustable quality of DBS permits therapeutic effectiveness to be enhanced, or stimulation-related side effects to be minimized. Preclinical and clinical studies have shown effects of DBS on brain regions functionally connected to the target of stimulation. Although its mechanisms of action are not fully elucidated, several effects have been proposed to underlie the therapeutic effects of DBS in movement disorders, and potentially in other conditions as well. Understanding the mechanisms of action of DBS is the current focus of a number of clinical and preclinical laboratories. Experience to date suggests that DBS may have potential to offer a degree of hope for patients with severe and treatment-resistant neuropsychiatric illness. The most data are available for obsessive-compulsive disorder, with consistently positive results across multiple smaller-scale studies. In contrast, work in treatment-resistant depression, which also suggests therapeutic potential, is at a much earlier stage. Further development of DBS for these illnesses will require a major commitment of resources across disciplines, including psychiatry, neurosurgery, neurology, neuropsychology, bioengineering, and bioethics. Investigations into new therapeutic indications for DBS should proceed cautiously.