Closed-loop systems for deep brain stimulation to treat neuropsychiatric disorders.

Introduction: A closed-loop or feedback-control system is a process which considers the system's output in order to automatically adjust the input. Compared to a traditional open-loop system, a closed-loop system allows for a higher degree of accuracy with minimal human intervention. Novel methods of closed loop 'adaptive' deep brain stimulation DBS (aDBS) are being developed.

Areas covered: This review focuses on the current state of aDBS for various neuropsychiatric conditions: common movement disorders such as Parkinson's disease, dystonia, essential tremor, and Tourette syndrome, as well as psychiatric disorders of depression and obsessive-compulsive disorder. Finally, the future directions of closed-loop neuromodulation treatments are also discussed.

Expert opinion: Recently, aDBS has been shown to offer benefits compared to open-loop DBS. Understanding the biomarkers of pathological states across various disorders is, however, crucial to implementation of aDBS, and improved sensing-capable hardware and advances in machine learning are poised to allow its effective implementation.