By Katrina Muñoz

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Adaptive deep brain stimulation (aDBS) systems are still in development but have emerged as a promising intervention to manage severe, refractory disorders from essential tremor to obsessive compulsive disorder (OCD). Unlike conventional DBS devices that simply deliver stimulation to the brain, aDBS is a closed-loop system that is responsive to a patient’s neural activity. This closed-loop system contains three defining features: the ability to measure neural activity, to automatically adjust stimulation, and to store neural activity data.

The potential promise of aDBS systems is that they will detect neural activity associated with symptoms, then adjust the delivery of stimulation in real time, modifying neural activity and managing symptoms (Arlotti et al., 2016; Shute et al., 2016). aDBS systems could be developed to deliver stimulation only when pathological brain activity is identified or as a continuous low amount of stimulation that increases when pathological activity is detected. This may reduce overtreatment, side effects, and depletion of batteries that need to be surgically replaced (Beudal and Brown, 2016; Hosain et al., 2014; Shukla et al., 2017). Moreover, the device’s ability to automatically adjust stimulation may prevent patients from having to experience suboptimal symptom management before their clinician is able to adjust stimulation, resulting in better patient outcomes (Klein, 2020).

Despite the potential promises of aDBS, bioethicists have raised concerns about these devices, arguing that the defining features of aDBS that give it promise could also heighten certain neuroethics concerns. For example, aDBS could potentially exacerbate concerns about patient agency and autonomy because devices modify stimulation automatically and these modifications likely occur outside patients’ conscious awareness (Gilbert et al., 2018; Gilbert et al., 2018; Goering et al., 2017). These concerns surface when discussing the degree of control that patients and clinicians should have over aDBS functionality. Promoting patient autonomy requires that clinicians do not have an excessive amount control and that patients have sufficient control over how their device operates (Fins, 2009; Goering et al., 2017). Clinicians can, for example, give patients control over stimulation parameters within a fixed range. Patients could also be given the ability to block an upcoming stimulation change that their aDBS device could alert them about. 

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However, promoting patient autonomy also requires that patients do not have too much control, as this could result in autonomy actually being undermined for certain patients. For example, in the case of OCD, the target is often the ventral striatum. Stimulation of this region of the brain can lead to hypomania (i.e., elevated mood and/or energy levels) and potentially to stimulation abuse. Hypomania is often associated with risk-taking behaviors and altered judgment, which may undermine autonomy (De Haan et al., 2017; Gilbert et al., 2017). Determining when a patient is experiencing these side effects is also challenging because clinicians often depend on self-report and caregiver perspectives, which may lead to some patients attempting to hide hypomanic symptoms. Additionally, empirical work (including by our research group) has indicated that patients generally trust their clinicians and may prefer that clinicians have a larger degree of control over stimulation (Klein 2016; Muñoz et al, 2020). Ensuring that clinicians maintain some degree of control over these self-operating devices is important for patients’ safety and sense of security. Clinician control is particularly important during emergencies or situations in which devices could respond to a false positive or false negative and stimulate inappropriately.

In order to find a balance between patient and clinician control over stimulation, it is crucial to evaluate individual patient preferences, different means of device control, and the particular brain target being employed. Clinicians and patients will also need to acknowledge the current experimental nature of aDBS systems given that these systems are still in development, with most projects not yet having found a valid biomarker (i.e., brain activity indicating pathology) to program devices (Provenza et al, 2019). Clinicians and patients should examine available evidence on the efficacy of aDBS for a given condition and assess potential risks that could require clinician intervention. Discussions around device control should include all relevant stakeholders, such as caregivers, patients, clinicians, and device programmers. Clinicians should also have ongoing conversations with patients and caregivers about aDBS functionality and the role of automaticity to ensure that patients feel adequately informed of their aDBS treatment. Our group’s findings suggest that different psychosocial supports, such as pre- and post-operative counseling, could also offer outlets for patients to discuss concerns or uncertainties about their aDBS care, which could allow problems to be prevented early on and at various points along a patient’s treatment trajectory (Muñoz et al., 2020).

Additional research and ethical analysis of device control, patient autonomy, and other challenges of aDBS systems is needed to fully understand and appropriately address potential neuroethics concerns. Bioethicists must specifically engage with the stakeholders that are directly involved in the development of these neurotechnologies, including patients, caregivers, researchers, clinicians, and others. Researchers interviewed by our group reported numerous other pressing ethical issues in aDBS research, including concerns about data security and privacy, automaticity and device programming, risks and safety, among others (Muñoz et al, 2020). Further insights into stakeholder perspectives will play a critical role in promoting the ethical development of aDBS and other next-generation DBS devices.