Study Suggests New Targets for Noninvasive Brain Stimulation to Treat Insomnia

By Scott Baltic

September 23, 2020

NEW YORK (Reuters Health) - Three specific brain regions - the bilateral supplementary motor area (SMA), right dorsolateral prefrontal cortex (DLPFC), and left superior temporal gyrus (STG) - could be new targets for noninvasive brain stimulation (NIBS) to treat chronic insomnia, researchers in China have found.

NIBS has recently been proposed as insomnia therapy, and most research has relied on DLPFC stimulation, Dr. Liang Gong of Chengdu Second People's Hospital, Chengdu, note in Sleep Medicine. Because the stimulation site could have implications for the technique's efficacy, studies of alternative targets are needed, they add.

"This study offers a more specific cortical 'map' for brain stimulation studies to treat insomnia," said Dr. Daniel J. Buysse, a professor of sleep medicine, psychiatry, and clinical and translational science at the University of Pittsburgh School of Medicine, in Pennsylvania, who was not involved in the work.

"If we know which brain areas to non-invasively stimulate or inhibit in order to affect sleep, we might have another treatment approach for insomnia, one that avoids the potential side effects of medications, and the effortful changes in behavior needed in cognitive behavioral therapy," he told Reuters Health by email.

"Sleep is regulated by multiple brain structures and circuits. Many of these are beneath the cortical surface of the brain, and as such, cannot be reached with NIBS," Dr. Buysse added. "One hopes that by stimulating cortical areas connected to these deeper structures, we might be able to alter sleep, but this has not yet been well demonstrated."

For their study, the researchers first identified sleep-associated regions of interest based on a meta-analysis of 154 previous neuroimaging studies related to sleep. They then assembled a cohort of 50 medication-naive patients (mean age, 38) with chronic insomnia and 33 healthy controls (mean age, 40) matched for age, sex and education.

These participants then underwent resting-state functional-connectivity (rsFC) MRI, which can detect brain networks based on correlated fluctuations in blood oxygenation, using the regions of interest as starting points.

Analysis of the resulting sleep-associated rsFC maps suggested that apart from the bilateral SMA, the right DLPFC and the left STG, the right middle temporal gyrus, the left DLPFC, the precentral lobule and bilateral supramarginal gyrus and angular gyrus, the superior frontal gyrus and the anterior temporal gyrus were could be potential targets for stimulation.

The authors note that "the ideal stimulation site is often ambiguous because the therapeutic mechanisms of NIBS are not clear."

Dr. Douglas Kirsch, medical director for sleep medicine at Atrium Health, in Charlotte, North Carolina, told Reuters Health by email, "Currently, NIBS is not approved in the U.S. for insomnia, solely for depression; however, it has been evaluated in some research related to sleep. Finding targeted sites for NIBS treatment of insomnia may allow NIBS to be used more effectively to improve sleep and become an approved treatment for insomnia."

Insomnia is best treated with cognitive behavioral therapy and, in some cases, medications, added Dr. Kirsch, who is also a clinical professor at the University of North Carolina School of Medicine.

"The search for better treatments, including those discussed in this paper, is important given that 10% of the U.S. population has chronic insomnia," he said. Dr. Kirsch did not participate in the research.

The study had no commercial funding and the researchers declared no conflicts of interest.

SOURCE: Sleep Medicine, online August 28, 2020.