Abstract: Deep Brain Stimulation (DBS), a rapidly developing neurotechnology, is emerging as a promising treatment for treatment-resistant depression (TRD). The clinical outcomes are certainly valid for people who have already failed all pharmacological and psychotherapeutic options; however, the prospect of DBS changing personality or identity, or impairing emotional depth, opens a slew of ethical, legal, and neuroscientific issues. Individual autonomy needs to be balanced with a moral consideration for the authenticity of the individual and the continuity of personhood.

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Introduction  

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Major depressive disorder (MDD) is one of the leading causes of disability worldwide; approximately 30% of individuals diagnosed with MDD present with treatment-resistant depression, characterized by having failed multiple lines of antidepressant treatments [1]. Deep Brain Stimulation (DBS), a specific neurosurgical procedure that places electrodes that deliver electrical signals to specific regions of the brain, has shown early efficacy for getting relief from their TRD symptoms. However, as DBS modifies neuronal activity in the mood-regulating network, questions arise regarding whether DBS not only affects depressive symptoms but could also affect aspects of personality, identity, or sense of self. Should society take the risk that the procedure may alter personality and identity in exchange for the possibility of symptomatic relief?

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Neuroscientific Basis for Concern 

 

     In the case of depression, DBS typically aims to modulate regions including the subcallosal cingulate cortex (Brodmann Area 25), ventral capsule/ventral striatum (VC/VS), and nucleus accumbens, all of which are intimately implicated in processes of affect regulation, motivation, and reward processing [4]. These regions do not operate in isolation; instead, they are nodes in distributed neural circuits that support cognition, emotion, and behavior. Because DBS modulates activity within these circuits, it raises concern over the extetn in which DBS produces meaningful changes to personality, behaviors or values. Each patient’s experience prompts existential questions about whether treatment restores the patient's identity or, in effect, transforms identity; and whether the post-DBS patient is the same agent who undertook the act to consent to the operation. Although a new hope, neuroscience adds a new level of uncertainty: where is the line between therapeutic change and undesired transformation?

     There is promising but still inconclusive clinical data regarding the effect of DBS in cases of TRD. A systematic review and meta-analysis carried out in 2024 investigated the data obtained from seven randomized controlled studies and eight open label trials. The analysis showed that there were positive results with regard to reduction of depression symptoms, but DBS is described by the researchers as an investigational intervention and the outcomes vary, which makes further investigations necessary [5]. This shows that the use of DBS can bring significant improvement in the treatment of certain patients with TRD, but at the moment its effectiveness cannot be considered proven. This ambiguity is especially important for ethical considerations, since when considering any benefits of an invasive procedure one needs to take into account the gaps in the existing evidence base [5]. 

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Philosophical and Ethical Considerations: Authenticity and Autonomy 

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     This question hinges on two criticisms that are related but distinct: authenticity and autonomy. Authenticity relates to the aspect of how much one's thoughts, feelings, and behavior embody their core identity. If DBS changes mood and behavior, and if this changes those behaviors in ways that feel superficial to the person through modification, this has implications for authenticity, even if that person may feel happier and more consistently happy. Consider learning about a person who has undergone DBS and wonders if they have lost their previously enjoyed hobbies and leisure activities; ended relationships that were important to them; and adopted values that feel profoundly unlike their own. Are they living someone else's life? Autonomy, on the other hand, revolves around having the ability to perform, provided they have both adequate information and are acting without coercion. An example of this would be a person who is extremely burdened by chronic severe depression may not be able to evaluate this information properly and may be in a state of impaired decision-making capacity because of hopelessness and cognitive perceptual distortions. Interestingly, if DBS minimizes or eradicates the symptoms of depression, it might restore autonomy that the depressive condition has eroded as a side effect. At the same time, though, this restoration of agency may also mean that the "self" deciding to undergo DBS is a different "self" than had been incapacitated by depression, and then perhaps they cannot be the person who gave consent to have the procedure done. 

     On a side note, bioethicists have discussed this in what has been called the "paradox of enhancement" [3], and raised the question of whether changing someone's mood also changes that person's moral agency. Should consent received pre-operatively be reconsidered post-operatively? The raised issues related to DBS identity situate it as an ethically more charged position, and a different ethical territoriality from that of psychotropic drugs or psychotropic therapy. 

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Clinical Ethics: Can DBS Be Offered Responsibly? 

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     While DBS remains ethically fraught, there may still be justification for its use if certain clinical conditions are met: 

1. Improved and Expanded Informed Consent 

Patients must be made aware of not just the procedural risks and therapeutic benefits, but also the risk of personality change, honest dialogue about uncertainty, reversibility, and the fundamental concepts of identity, which should mark the consent process as iterative, not single point-in-time.

2. Long-term Ethical Oversight 

DBS should not be treated as a single mode of intervention. DBS should be accompanied by long-term psychiatric follow-up, ethical review, and psychosocial monitoring, and allow for the clinician and patient to come back to their goals and contextualized experiences long after the treatment.

3. Respect for Narrative Identity 

Clinicians should help patients understand the concept of 'narrative identity,' or how the patient defines themselves over time. For patients who express concern that the procedure may change them into someone they do not know or recognize as their 'self/identity,' then this concern must be treated as being serious, and likely means the procedure will not be tolerated. However, if the patient defined relief from TRD as a return to the patient’s 'true' self, then perhaps DBS is not viewed as distorting a patient's identity but restoring it. 

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Legal and Policy Dimensions 

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     Legally, DBS creates significant issues of capacity, liability, and consent. Courts have recognized surgical interventions in cases of intractable conditions for multiple decades, as long as the patient could make decisions. Nevertheless, if DBS engenders new forms of judgment or unexpected behaviors (e.g., increased impulsivity, risk-taking), there could be liability for the clinicians and the manufacturer of the device. Legal challenges with psychiatric DBS include obtaining proper consent and attributing responsibility for any unforeseen consequences of the procedure. As DBS is an invasive procedure with long-term uncertain effects, the clinicians have to ensure the patients understand both the risks and benefits of the treatment. While depressed patients may find decision making harder, depression in itself is not enough for diagnosing the incapacity of the patient to give consent, and the capacity needs to be determined on a case-by-case basis. Should the DBS procedure lead to any unexpected alterations in judgment or behavior, the question of who bears the legal responsibility for the consequences whether the patient, the clinician, or the producer of the device, may be challenging. 

     Since deep brain stimulation for treatment-resistant depression is an investigational therapy, the development of DBS intervention also brings up issues related to research regarding evaluation of outcomes other than improvement of depressive symptoms. Variation in DBS outcomes was found in the 2024 systematic review of clinical trials of DBS according to anatomical targets and study design, which illustrates the need for further research not only regarding the efficacy but also the potential adverse effects of DBS [5]. Because DBS is an invasive intervention whose benfits must be weighed agaisnt the risks, the limitations of the current evidence are also relevant to the ethical question of how and when DBS should be offered, especially when considering the changes in quality of life and other parameters of well-being, as considered by patients. 

     In particular, neuroethics research on DBS has focused on such aspects of the self as identity, authenticity, and autonomy and suggested that these aspects could be used in the assessment of the impact of neuromodulation [6]. Even though this line of research has not confirmed the fact that DBS necessarily changes the identity of patients, it is possible to state that patients' perception of their own treatment is important in addition to the traditional assessment methods. 

 

Conclusion 

 

     DBS for treatment-resistant depression holds both promise and danger. It has the potential to give some individuals trapped in suffering the experience of living again, while there is the possibility of an altered identity. Should we offer it? Yes, but thoughtfully and with a system of ethical oversight is necessary to provide care that sees patients as people with stories, fears, and values rather than brains needing fixing. Autonomy and authenticity do not need to be adversaries when the clinical world is anchored in humility, integrity, and multiple opportunities to care.