In a small study, researchers funded by the National Institutes of Health captured more than 1,000 hours of brain recordings from patients with OCD in the clinic and at home. These data are a key first step towards designing improved deep brain stimulation (DBS) treatments for neuropsychiatric disorders. DBS has shown great promise for improving the lives of people living with neurological disorders such as Parkinson's disease, and is now gaining traction for treating psychiatric conditions such as obsessive-compulsive disorder (OCD). The study is published in Nature Medicine and funded through the NIH Brain Research Through Advancing Innovative Neurotechnologies (BRAIN) Initiative.
By combining at-home and in-clinic brain recordings, this study could aid in the development of adaptive DBS treatments, which could be transformative for people living with OCD. This kind of far-reaching, high-impact work is precisely what the BRAIN Initiative was established to support."
John J. Ngai, Ph.D., Director, NIH BRAIN Initiative
Researchers, led by David Borton, Ph.D., associate professor of biomedical engineering at Brown University, Providence, Rhode Island, and Wayne K. Goodman, M.D., the D.C. and Irene Ellwood Chair in Psychiatry at Baylor College of Medicine, Houston, collected brain recordings from three patients who were already receiving DBS treatment for OCD. These recordings occurred in the clinic, during teletherapy sessions, and during normal life activities at home. These data will be used to correlate specific brain patterns with OCD symptoms, with the goal being the identification of neural signatures and related behaviors that predict the onset of symptoms and that can be used to further refine DBS treatment. The at-home component to the recordings is a particularly important advancement, since that is the environment where patients are being exposed to the triggers that affect their daily lives.
OCD and other neuropsychiatric disorders are challenging to treat with DBS because the symptoms fluctuate over time. Unlike motor disorders, such as Parkinson's disease that are commonly improved with DBS, the symptoms of OCD come and go over time and can be triggered by the person's environment.
"Currently, DBS therapy for OCD involves implanting the electrodes, turning on the stimulation, and then fine-tuning that stimulation as best as possible in the clinic," said Dr. Borton. "But because symptoms can be triggered by many factors, the clinician is tuning the DBS system for the patient at that moment in the clinic, but their needs could change significantly once they leave the clinic."
Another enormous challenge is the current lack of biomarkers—distinct and measurable changes in brain activity—for OCD symptoms. In addition, changes in symptoms in response to DBS for neuropsychiatric disorders can take weeks or even months to occur once treatment begins. This means that clinicians programming the DBS system must rely on secondary behavioral changes such as a positive affect response—patients feel happier or more talkative when stimulation is turned on.
"Changes in affect can tell us that we are stimulating the right area of the brain, but not necessarily that the stimulation itself is ideally tuned," said Dr. Goodman.
The researchers in this study aimed to tackle these challenges by using a technology similar to what had been previously used by BRAIN Initiative investigators in patients with Parkinson's disease.
In the current study, brain recordings were taken from the same electrodes responsible for delivering the DBS therapy and time-synched to EEG, other physiological recordings, and facial changes when recorded in the clinic; to efforts to evoke symptom responses during teletherapy sessions; and to self-reported symptoms during everyday life and during prescribed tasks at home.
By combining these diverse data sets, the researchers were able to begin identifying candidate neurological signatures for OCD, such as brain activity changes that occurred over time in correlation with clinical scores for OCD symptoms. Going forward, the researchers plan to tweak the stimulation in response to the candidate biomarkers to confirm whether they can be used to impact the onset of symptoms. In addition, recordings from the cortical surface of patients, similar to what was done in the study of Parkinson's disease, will be added to provide an additional layer of information.
Provenza, N.R., et al. (2021) Long-term ecological assessment of intracranial electrophysiology synchronized to behavioral markers in obsessive-compulsive disorder. Nature Medicine. doi.org/10.1038/s41591-021-01550-z.