Despite conscientious compliance and adherence to treatment according to internationally accepted evidence based treatment algorithms, some patients with psychiatric disorders do not respond to pharmacotherapy and psychotherapy treatment. Such patients are treatment refractory and are severely incapacitated and have a very low quality of life .

Deep brain stimulation (DBS) is under investigation as a new treatment for an increasing number of psychiatric conditions. Pilot studies in recent years have begun to demonstrate efficacy of DBS as a possible novel therapeutic modality for patients suffering from a severe form of these psychiatric disorders.

DBS for psychiatric disorders has evolved from a history of stereotactic ablative neurosurgery . If research of DBS proves non-inferiority in comparison to ablative techniques, DBS may be more acceptable than brain lesioning for patient and general public due to its adjustability and reversibility.

Obsessive compulsive disorder (OCD) was the first psychiatric disorder where the use of DBS was investigated, and sustained beneficial effects were documented by several research groups worldwide [3, 7, 11, 14]. Increasingly, DBS becomes a focus of research for other psychiatric indications such as major depressive disorder [9, 12, 16], addiction [13], eating disorders [8] and impulse control disorders [10].

In this developing domain of DBS for psychiatric disorders, it is of crucial importance to define and accept guidelines that respect the cultural and religious diversity and heterogeneity of healthcare environments of internationally collaborating partners. Such guidelines state a set norms at a given time but can and will evolve in an iterative process, taking into account the evolution of scientific findings, the continuing technical developments and the clinical experience gathered from patients living with DBS. They are meant to guide ethical and effective research and represent an international multidisciplinary consensus on best ethical practices, norms and professional behaviors, both in clinical and research settings [15].

Due to the stringent inclusion criteria, the year prevalence of DBS in psychiatric disorders during the last decade is low [6]. Patients that are candidates for DBS trials have a longstanding course of impairment and are disappointed by many failed treatments.

The DBS process in order to optimize treatment outcome can be divided in sequential phases: ethics of the clinical decision making process, selection procedure of appropriate candidates and preoperative evaluation, surgical intervention, post-surgery treatment and long term follow-up. Problems can emerge at each phase and a patient’s progress through this DBS process requires careful monitoring and adequate interventions from multidisciplinary team.

According to the World Health Organization [19] it is a patient’s right to be offered a treatment that can alleviate suffering and permits improvement in quality of life . If there is enough evidence that DBS can lead to significant relief of symptoms and improvement of quality of life , it seems unethical not to consider the issue of DBS for carefully selected patients.

The protection of the human rights and dignity of psychiatric patients is a major issue and provides the frame to discuss the ethical principles of this ultimate therapeutic approach. Specific normative problems have to be considered such as safety concerns, the best interest of the patient, questions of patient’s autonomy and ability to give free informed consent.

The risk/benefit ratio of the surgical intervention should be favorable Expectations and values of the patient and significant others are considered against the potential benefits of the procedure, as established in the context and at the time of the DBS procedure.

The compliance of patients to former treatment plays a role in the decision-making process as a good follow-up after the neurosurgical procedure is a crucial factor. Not only the symptom relief, but transformation of symptom relief into improvement in general wellbeing and amelioration in quality of life depends on this compliance.

The clinical decision making process needs to be considered in the context of a given era and society, with its specific role definitions, customs, moral views and laws. Knowledge of treatment efficacy, risks and alternative treatments and ethical status of DBS may change over time. The perspective of the patient, his/her values, quality of life and consent to treatment need to be taken into account. Regular accurate reviews of available literature on targets, indications, results and adverse events are crucial in this developing field. Honest and solid scientific reporting on the effectiveness and burden of these invasive procedures are an ethical duty of research centers who engage themselves in DBS for psychiatric disorders . To improve benefits and reduce risks, research into the precise definition of the brain target may help. Improvements in the field of technology and biomedical engineering may make interventions less invasive and less destructive. Advances in structural and functional neuroimaging and anatomic and electrophysiological studies, along with microelectrode technology, allow for more precise characterization of the neural pathways involved in certain disease states. However, microelectrode recording may increase the risk for brain haemorrhage, especially when approaching new brain areas via new trajectories, and this increased risk should be weighed against the possible advantage of its use.

DBS influences signal transduction and brain activity. The intention of “ideal” DBS is to normalize pathological brain signals without impact on non-pathological brain activity. The precise neurophysiologic mechanisms of psychiatric disorders and mechanism(s) of action of DBS are not yet fully understood. At the current level of knowledge, we have no strict delineation between pathological and non-pathological brain activity for psychiatric disorders. Knowledge on electrophysiological biomarkers is only very preliminary. DBS is under investigation in several different brain targets and for different psychiatric indications. DBS is not ultimately accurate. It does not only modulate pathological brain circuits. It may also influence other areas which cause unwanted effects. Furthermore, a brain circuit may dysfunction only intermittently. DBS in that circuit may at certain moments be beneficial for the patient, and at other moments have no influence, or even provoke unwanted effects.

The concept of autonomy in this chronically ill, severely impaired patient population needs further development and differentiation [1]. Respect for self-determination is undeniably important, but the intense chronic suffering and vulnerability influence the patients’ decision-making process. Some patients want to be fully involved in the deliberative consent process, others defer decision-making to significant others or the physician in charge [18]. A psychiatric disorder does not affect patients alone, but can have a profound and devastating impact on those around them. The involvement of significant others and caregivers in medical decision-making process needs to be acknowledged [2]. Patients depend on these caregivers. Assessment of the expectations and values of both patient and significant others is crucial. Caregivers and patients may have divergent values and priorities, influenced by the burden created by patient’s disorder. This can represent an additional, largely unrecognized, source of vulnerability in psychiatric patients. The influence of caregivers or close thirds can potentially translate into taking on additional ‘involuntary’ risks, including clinical trial enrollment. A dependent relation may result in undesirable pressure on the patient to adopt the caregivers preferences, and their involvement can counter patient autonomy and best interests. An acceptable approach is to consider the psychiatric disorder as a problem of a particular patient as well as to bear in mind the disruptive effects of the patient’s psychiatric disorder on significant others. Conceivable secondary gains and expectations from caregivers need clarification before the patient decides to undergo DBS [4]. The effects of DBS reach (indirectly) beyond effects on disease symptoms and not only the patient but also these significant others will have to adapt to a new situation.

Although in psychiatric disorders cognitive distortions and biases may be present, carefully instructed patients (eventually with the aid of a family member, trusted counselor and/or legal guardian) are able to consent to complex, high-risk treatment or research proposals. Patients with treatment refractory psychiatric disorders often initiate the plea for DBS themselves. The very strong and demanding claim for surgery looks in fact closer to a desire than to a statement for informed consent. They may request disproportionate treatments and their desperation may impair their ability to rationally weigh the benefits against the risks. It is this paradoxical ease of securing consent in these patients that requires a higher degree of responsibility from DBS teams in the informed consent process. The patient must fully understand the risks and possible benefits and special attention regarding the concept of therapeutic misconception in the case DBS is required. This concept needs to be actively addressed, without withdrawing every hope the patient has put in the intervention. Furthermore, we want to emphasize the ethical requirement that individuals, participating in trials on DBS for psychiatric disorders, should not be used merely as a mean to increase our scientific knowledge, but always as an entity of their own. The aim of research on therapeutic innovations such as DBS for psychiatric disorders gives priority to the patient, who’s safety exceeds the stringent application of the research protocol.

DBS is an intracranial neurosurgical procedure that comes with limited but significant risks. Aside from multidisciplinary assessment to determine suitability for the procedure, the patient must be able to give informed consent. Patients should also be counselled for the possibility that they may derive no benefit from DBS or not tolerate it well, necessitating the devices to be either switched of, or even their complete removal.