Safety and Neuroethical Consideration of Deep Brain Stimulation as Psychiatric or Dementia Treatment

Introduction

This article will summarise the results of two studies related to the use therapeutic use of deep brain stimulation (DBS) and will provide an overview of some of the key ethical issues related to DBS used both for therapy and for "human enhancement". The study is interview-based and discusses the views of physicians and patients on the use of DBS to treat psychiatric disorders. The article then summarises the results of a Canadian clinical trial of DBS in Alzheimer's patients. The subsequent review of ethical issues raised by DBS for therapeutic as well as cognitive enhancement purposes will address such issues as risk factors, informed consent and conflict of interest questions.

DBS is a surgical medical treatment involving the implantation of a medical artificial device which sends electrical impulses to specific parts of the brain. In DBS, electrodes are connected by wires to a type of pacemaker device (called an impulse generator) implanted under the skin of the chest, below the collarbone. The impulse generator can easily be programmed using a computer that sends radio signals to the device. DBS can directly change brain activities in a controlled manner, and its effects are generally mild and reversible.^{1, 2}

DBS in the selected brain areas has provided remarkable therapeutic benefits to treat a variety of disabling neurological symptoms — most commonly the symptoms of Parkinson's disease (PD), such as tremors, rigidity and slowed movement. At present, the procedure is used only for patients whose symptoms cannot be adequately controlled with medications.

Lately, in advanced nations, the clinical trials of DBS have been applied for various psychiatric disorders, such as obsessive compulsive disorder (OCD), Tourette syndrome (TS) and severe depression.³ It has also been tested in a few patients for other conditions such as Alzheimer's disease (AD), obesity, a minimally conscious state after a traumatic brain injury⁴ and addiction. Though the data are intriguing, there is insufficient evidence to support DBS as a therapeutic modality for these conditions. We must examine the safety of such therapies, and clarify the conditions for proper application of the DBS technique.

Previous medical practices such as prefrontal lobotomy revealed many problems and concerns which needed to be resolved. Prefrontal lobotomy provides a valuable historical lesson as human neuroscience progresses. This operation did help people but had adverse effects that were not fully known or disclosed.⁵ Therefore, the new techniques of DBS must define its criteria, procedure and ethical boundaries in avoiding possible bioethical mistakes.

On the other hand, some scientists are warning that the neural device such as DBS will introduce a possibility of "brain hacking". In spite of this risk, neural devices are not created with security as yet. We will briefly consider neurosecurity as well as neuroethics in this article.

Our Investigation on the Effects and Safety of DBS for Psychiatric Disorders

We researched the effects and safety of DBS therapies for psychiatric disorders under NEDO International Research Project in 2007-2008.⁶ We investigated 1) the safety of DBS electrodes, 2) the safety of DBS procedures for psychiatric purpose, 3) the role of clinical coordinators who mediate between patients (or end users) and DBS clinicians, 4) the social concerns about personality changes/brain plasticity, 5) lessons from the past: re-examination of ethical debates of prefrontal lobotomy, 6) possible use for the purpose of brain enhancement, 7) end users' expectations and fears towards brain stimulation, and 8) a comparison of DBS with electroconvulsive therapy. The main focus of the project was to determine the critical issues of brain stimulation technologies as psychiatric treatment in the Japanese clinical scene.

Research methods were 1) interviews with researchers at academic institutes that are engaged in developing DBS electrodes, 2) interviews with physicians, neurologists, neuroscientists who are involved in DBS therapy, 3) interviews with patients who underwent DBS, 4) interviews with coordinators who mediate between patients and physicians, and 5) a survey of the literature — academic articles, government documents, and other records — both in Japan and the USA.

The hospitals visited, and people interviewed are the following...