The approach may help "enable neural biomarker identification, a prerequisite for future development of adaptive DBS for OCD and other psychiatric disorders," the study team writes in Nature Medicine.
"Neuropsychiatric illnesses are not static - symptoms wax and wane, and in some cases they are exacerbated by environmental, social, or internal triggers as in OCD," explained senior author Dr. David Borton, an associate professor of biomedical engineering at Brown University and a biomedical engineer at the U.S. Department of Veterans Affairs Center for Neurorestoration and Neurotechnology. "Current DBS therapy is effective, but it does not automatically adjust to the moment-by-moment needs of patients."
"In this study, we collected brain recordings from the same device delivering the DBS therapy, from five participants over 1,000-plus hours during daily activities," Dr. Borton told Reuters Health by email. "In this data, we have found evidence of objective markers that could be used to update stimulation settings moment-to-moment, in sync with the needs of people with OCD."
The patients in the study had severe OCD and were eligible for DBS treatment. The neurosurgeon on the team implanted an investigational DBS device from Medtronic that was capable of both delivering stimulation and recoding local field potentials (LFPs).
Along with the electrical data, the team also collected a suite of behavioral biomarkers via video and smart watch, which provided information such as heart rate and activity levels. The behavioral measures were then time-synched with the brain sensing data, which enabled the researchers to look for correlations between the two.
Using computer-vision machine-learning techniques, the researchers discovered that behavioral features could be associated with electrical changes in the brain. In particular, they noted a correlation between frequencies of 0-4 Hz, the delta band, and OCD-symptom intensity.
"This is the first study to collect brain recordings and behavioral data across a wide range of settings in neuropsychiatric participants - understanding the full scope of the findings will take many years," Dr. Borton said.
The new study is "a nice piece of work," said Dr. Brian Kopell, director of the Center of Neuromodulation at the Mount Sinai Health System in New York City, who was not involved in the research. "The big challenge in treating psychiatric disease has been the utter reliance on patient reporting on the aspects of their symptomatology. At the end of the day, that is incredibly limited."
DBS devices like the one used by Dr. Borton and his colleagues may be able to get around that problem because they "not only stimulate the brain, but also listen to the key circuits. Correlating that data with all sorts of aspects of human behavior - for example facial movement - can give us ways to measure the way humans interact with the environment and hopefully help us redefine what these diseases are and hopefully guide the treatments."
The hard part, Dr. Kopell said, is finding ways to marry the different types of data together to show the way to better treatments. "Until the data we collect has demonstrated real utility, it's just a fun science project," he added.
"This study is methodologically very important because for the first time the authors show the feasibility of collecting intracranial electrophysiological events, LFPs, not only in a lab setting but at the patients' homes and while they were experiencing symptoms using the ecological momentary assessment methods or EMA," said Dr. Nicola Cascella, an assistant professor in the department of psychiatry and a faculty member of the Johns Hopkins Schizophrenia Center in Baltimore, Maryland.
"The findings of a correlation between the delta band and symptoms intensity will need to be replicated in a bigger sample but it shows the potential of identifying a biomarker that is objectively related to OCD symptoms," Dr. Cascella told Reuters Health by email. "If confirmed it will be the foundation of adaptive DBS system to treat OCD."
"I think that this methodology and the tools used in this study could be used to study other neuropsychiatric disorders," Dr. Cascella said. "Indeed, we have applied for NIMH funding for a very similar study in treatment-resistant schizophrenia where we will monitor auditory verbal hallucinations using EMA methods and, in the lab setting, while recording LFPs and EEG."
SOURCE: https://go.nature.com/3DSCLz3 Nature Medicine, online December 9, 2021.
By Linda Carroll
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