Neurotechnology is rapidly expanding the realm of medical possibility. Consider, for example, individuals with paralysis who have lost the ability to communicate. Recent advancements in brain computer interfaces (BCIs) offer reason for hope for these patients: By establishing a connection between the brain and a digital device, these systems grant patients a new means by which to express themselve and interact with the world. (Learn more in this NeuroExplainer.)

Although assistive communication is the most imminent application of BCI, with clinical trials slated to begin over the next year, it’s hardly the only application under consideration. This technology could revolutionize how we treat conditions ranging from motor deficits to treatment-resistant mental illness—allowing millions of people to live happier, healthier, and more enriching lives. 

Direct neural-to-digital communication

The brain engages in constant conversation with the rest of the body. Your sensory organs tell your brain what’s happening in the world around you; and, in turn, your brain tells your muscles what to do. When these communication channels are compromised, sensory or motor impairment follows. For example, if your eyes can't communicate with your brain, you will experience blindness; and if your brain can’t dialogue with your muscles, you’ll suffer from motor impairment. 

BCI offers a solution to this type of problem. By establishing a lingua franca among biological and digital signals, this technology creates a new channel for passing information into and out of the brain. In someone with paralysis, for instance, the interface might gather signals from neurons in the motor cortex and use this data to guide a wheelchair, exoskeleton, or prosthetic limb. And, indeed, BCI control of robotic prosthetics has been achieved in clinical trials.  

Reconnecting lost senses

Likewise, BCI systems can bridge the gap where sensory function is lost. That is, a prosthetic sensor–such as a digital microphone or a camera—collects information from the environment and delivers it to an interface that electrically stimulates the brain. For example, people are currently benefiting from auditory brainstem implants—devices that receive input from a microphone and translate this data into a stimulation pattern that the brain understands as sound. Scientists are also investigating new solutions for deafness.

For some people, sensory and motor impairment come as a tragic package deal. Those with paralysis often lack the ability both to control and feel the affected body parts. Researchers are therefore honing BCI systems that would solve both problems at once, bidirectional systems that provide both neurosensing and neurostimulation. For instance, a BCI used in conjunction with a bioelectronic sleeve restored some movement and sensation to the hand of a patient paralyzed by spinal cord injury.

Note that, even as these systems advance, they don’t perfectly simulate a lost sense or limb. “Seeing” with a bionic eye is not the same as seeing with a biological eye; just as a BCI-guided prosthetic will never feel quite the same as the arm it replaces. Yet, as technology advances, complete functional restoration may be possible. In fact, it is reasonable to anticipate a future in which BCI enables capabilities humans do not currently possess–like the ability for bionic eyes to “see” in infrared

Treatment for tricky neurological disorders

Globally, as many as one billion people live with neurological disorders, with about one-third of  Americans affected by at least one of the more than 1000 neurological disorders, such as multiple sclerosis, epilepsy, stroke, and dementia. Despite these staggering statistics and decades of research, many sufferers lack effective treatment options. For example, little can be done to curb the effects of progressive dementia; and 1 in 5 people with epilepsy do not respond to medication. As such, researchers are looking to new approaches, including BCI, to manage these conditions.

A precedent exists for using implantable technology to treat neurological disorders. Since its FDA approval in 2002, certain individuals with Parkinson’s disease (PD) have benefited from deep brain stimulation (DBS)–a kind of neural pacemaker that delivers electrical pulses to brain cells involved in movement. By correcting abnormal firing patterns, DBS can control PD symptoms like tremor, slow movement, and rigidity. 

The success of DBS for PD demonstrates that implantable neurotechnology can be a safe, practical, and effective means by which to treat debilitating disease–particularly for patients who don’t improve with traditional medications. This opens the door for BCI to fill therapeutic gaps left by drugs ill-equipped to resolve complex brain disorders. In fact, BCI may prove more effective and widely applicable than DBS because it allows for recording of brain signals, concurrent with stimulation. This bidirectional action allows clinicians to better understand the brain network involved in disease, permitting  dynamic and personalized treatment. Such an approach is well suited to neurodegenerative disorders that require treatment to evolve with the disease. 

BCI may also play a significant role in the future of disease recovery. Stroke survivors, for instance, risk developing speech problems, cognitive impairment, depression, paralysis, and more. This population would therefore benefit from BCIs for assistive communication and motor impairment, as previously described. The FDA has already approved a noninvasive BCI system that restores hand movement in post-stroke patients. Though these devices show promise, implantable BCIs stand to dramatically surpass their effectiveness, as this technology interacts with the brain in a much more precise and reliable way. 

Many neurological disorders disproportionately affect older individuals. Approximately two-thirds of Americans experience some level of cognitive decline at the age of 70 or older. As such, more effective treatment of conditions like stroke and dementia could bring about profound improvements in quality of life among adults in their golden years. In this sense, BCI may radically alter not just brain medicine, but what it means to age. 

Better solutions for people with mental illness

Over 45% of Americans will experience mental illness at some point in their life, with the most common diagnoses being anxiety, depression, obsessive compulsive disorder (OCD), and post traumatic stress disorder (PTSD). To manage these conditions, most people use one or more psychiatric medications, complemented by psychotherapy. In some cases, this approach is effective; in others, however, drugs don’t help or cause disruptive side effects. Up to 40% of people with anxiety, for instance, do not improve with first-line treatments. And about 31% of patients diagnosed with major depressive disorder experience treatment resistance.

The drawbacks of psychiatric medication–both their side effects and lack of efficacy–can be attributed to the fact that they’re not terribly specific. Most drugs travel through the brain without prejudice, affecting groups of neurons that have little to do with the problem at hand. BCI, by contrast, is designed to target only the neurons driving illness.

Again, we can look to DBS as precedent for a neurotechnological approach. Research studies using this technique have shown success for patients with treatment-resistant depression and OCD—conditions that are debilitating without proper management. This treatment has been referred to as a “Pacemaker for the brain”, and has shown early promise.

She tried nearly every treatment: roughly 20 different medications, months in a hospital day program, electroconvulsive therapy, transcranial magnetic stimulation. But as with nearly a third of the more than 250 million people with depression worldwide, her symptoms persisted. Then Sarah became the first participant in an unusual study of an experimental [DBS] therapy. Now, her depression is so manageable that she’s taking data analysis classes, has moved to her own place and helps care for her mother, who suffered a fall. (A ‘Pacemaker for the Brain’: No Treatment Helped Her Depression — Until This, New York Times)

Admittedly, the effectiveness of DBS for mental illness varies, likely because mental illness itself can arise from a wide range of biological causes: the brain of one person with depression may behave quite differently from that of another person with depression. For instance, researchers have shown that different depression subtypes correlate to different patterns of dysfunctional connectivity within the brain’s network. Encouragingly, BCI is well-suited to treating diseases with this kind of etiological diversity. In the future, this technology may be able to identify brain networks driving illness in a particular person and, accordingly, deliver a brain stimulation regimen specific to that network.

Indeed, BCI has the potential to revolutionize not just how we treat psychiatric conditions, but also how we think about them. For decades, mental illness has been modeled as a chemical imbalance, largely because we use chemical medications to treat it. Yet, this model of disease does not adequately explain when and why psychiatric and mood disorders arise. BCI may help us fill some of these critical knowledge gaps. Researchers have identified the relationship between patterns of brain activity and mood and in turn have demonstrated a mood state “decoder”. 

Our goal is to create a technology that helps clinicians obtain a more accurate map of what is happening in a depressed brain at a particular moment in time and a way to understand what the brain signal is telling us about mood. This will allow us to obtain a more objective assessment of mood over time to guide the course of treatment for a given patient. (Maryam Shanechi, PhD, research lead in the mood “decoder” study)

A new medical paradigm

Up until now, the beneficiaries of BCI have been limited to the laboratory setting for patients with paralysis. Yet, as the technology continues to mature, and we learn from early users, a variety of new clinical applications will emerge. For instance, at Paradromics, we are developing the Connexus Direct Data Interface, a BCI which gathers data from an unprecedented number of neurons, offering neural recording with an incredible degree of precision. As such, it has the potential to help scientists and doctors better understand and treat a wide range of neurological and brain disorders. Indeed, BCI represents a powerful new tool that stands to transform brain medicine and, in the process, improve countless lives. 

References

Belluck P. A “Pacemaker for the Brain”: No Treatment Helped Her Depression — Until This. The New York Times. https://www.nytimes.com/2021/10/04/health/depression-treatment-deep-brain-stimulation.html. Published October 4, 2021.

Bockbrader M. Upper limb sensorimotor restoration through brain–computer interface technology in tetraparesis. Current Opinion in Biomedical Engineering. 2019;11:85-101. doi:10.1016/j.cobme.2019.09.002

Breakthrough brain research could yield new treatments for depression. USC News. Published September 10, 2018. Accessed July 6, 2022. https://news.usc.edu/148570/breakthrough-brain-research-could-yield-new-treatments-for-depression/

Bystritsky A. Treatment-resistant anxiety disorders. Molecular psychiatry. https://pubmed.ncbi.nlm.nih.gov/16847460/. Accessed June 14, 2022

Drysdale AT, Grosenick L, Downar J, et al. Resting-state connectivity biomarkers define neurophysiological subtypes of depression. Nature Medicine. 2016;23(1):28-38. doi:10.1038/nm.4246

Ganzer PD, Colachis SC 4th, Schwemmer MA, et al. Restoring the Sense of Touch Using a Sensorimotor Demultiplexing Neural Interface. Cell. 2020;181(4):763-773.e12. doi:10.1016/j.cell.2020.03.054

Gardner J. A history of deep brain stimulation: Technological innovation and the role of clinical assessment tools. Social Studies of Science. 2013;43(5):707-728. doi:10.1177/0306312713483678

Gooch CL, Pracht E, Borenstein AR. The burden of neurological disease in the United States: A summary report and call to action. Annals of neurology. 2017;81(4):479-484. doi:10.1002/ana.24897

Groiss SJ, Wojtecki L, Südmeyer M, Schnitzler A. Deep brain stimulation in Parkinson's disease. Ther Adv Neurol Disord. 2009;2(6):20-28. doi:10.1177/1756285609339382

Hale JM, Schneider DC, Mehta NK, Myrskylä M. Cognitive impairment in the U.S.: Lifetime risk, age at onset, and years impaired [published correction appears in SSM Popul Health. 2020 Dec 10;12:100715]. SSM Popul Health. 2020;11:100577. Published 2020 Mar 31. doi:10.1016/j.ssmph.2020.100577

Kessler RC, Berglund P, Demler O, Jin R, Merikangas KR, Walters EE. Lifetime prevalence and age-of-onset distributions of DSM-IV disorders in the national comorbidity survey replication. Archives of General Psychiatry. 2005;62(6):593-602. doi:10.1001/archpsyc.62.6.593

Kong ST, Ho CS, Ho PC, Lim SH. Prevalence of drug resistant epilepsy in adults with epilepsy attending a neurology clinic of a tertiary referral hospital in Singapore. Epilepsy Research. 2014;108(7):1253-1262. doi:10.1016/j.eplepsyres.2014.05.005

Kuchta J. Neuroprosthetic Hearing with Auditory Brainstem Implants / Wiederherstellung des Hörens durch auditorische Hirnstammimplantate. Biomedizinische Technik/Biomedical Engineering. 2004;49(4):83-87. doi:10.1515/bmt.2004.017

Lim HH. Development and Translation of an Intracranial Auditory Nerve Implant. Nih.gov. Published 2022. https://reporter.nih.gov/project-details/9588697

Nowik K, Langwińska-Wośko E, Skopiński P, Nowik KE, Szaflik JP. Bionic eye review – An update. Journal of Clinical Neuroscience. 2020;78:8-19. doi:10.1016/j.jocn.2020.05.041

Sani OG, Yang Y, Lee MB, Dawes HE, Chang EF, Shanechi MM. Mood variations decoded from multi-site intracranial human brain activity. Nat Biotechnol. 2018;36(10):954-961. doi:10.1038/nbt.4200

Scangos KW, Makhoul GS, Sugrue LP, Chang EF, Krystal AD. State-dependent responses to intracranial brain stimulation in a patient with depression. Nature Medicine. 2021;27(2):229-231. doi:10.1038/s41591-020-01175-8

Starr PA. Totally Implantable Bidirectional Neural Prostheses: A Flexible Platform for Innovation in Neuromodulation. Frontiers in Neuroscience. 2018;12. doi:10.3389/fnins.2018.00619

Voelker R. Helping Patients Improve Muscle Movement After Stroke. JAMA. 2021;325(21):2143. doi:10.1001/jama.2021.7913

World Health Organization. Neurological Disorders : Public Health Challenges. World Health Organization; 2006.

Wu H, Hariz M, Visser-Vandewalle V, et al. Deep brain stimulation for refractory obsessive-compulsive disorder (OCD): emerging or established therapy? Molecular Psychiatry. Published online November 3, 2020. doi:10.1038/s41380-020-00933-x

Zhdanava M, Pilon D, Ghelerter I, et al. The Prevalence and National Burden of Treatment-Resistant Depression and Major Depressive Disorder in the United States. The Journal of Clinical Psychiatry. 2021;82(2). doi:10.4088/jcp.20m13699