Megan Brooks

June 05, 2013

BALTIMORE, Maryland — Dysfunction in the neural circuitry underlying emotion regulation may have a role in insomnia, new research hints. The findings could have implications for the risk relationship between insomnia and depression, the researchers say.

"Insomnia has been consistently identified as a risk factor for the subsequent development of depression, but it is not clear why this is the case," lead researcher Peter Franzen, PhD, assistant professor of psychiatry, University of Pittsburgh School of Medicine in Pennsylvania, told Medscape Medical News.

"Abnormalities in how emotion is processed, and perhaps more importantly, how one is able to voluntarily alter their emotional responses" may be involved, he explained.

Dr. Franzen will present the study findings here June 5 at the SLEEP 2013: Associated Professional Sleep Societies 27th Annual Meeting.

Emotional Overdrive?

The study involved 14 individuals with chronic primary insomnia without other primary psychiatric disorders as well as a control group of 30 good sleepers.

Dr. Peter Franzen

All participants underwent functional MRI during an emotion-regulation task in which they were shown negative or neutral pictures. They were asked to passively view the images or to decrease their emotional responses using cognitive reappraisal, a voluntary emotion-regulation strategy in which the subject interprets the meaning depicted in the picture in order to feel less negative about it.

The researchers observed in the primary insomnia group that activity in the amygdala — the brain's emotional processing and regulation center — was significantly higher during cognitive reappraisal than during passive viewing (P = .01).  This response pattern is opposite that observed in previous studies of healthy individuals, they say.

In analysis between groups, amygdala activity during reappraisal trials was significantly greater in the primary insomnia group than in good sleepers (P = .05). The 2 groups did not significantly differ when negative pictures were passively viewed.

"Previous studies have demonstrated that successful emotion regulation using reappraisal decreases amygdala response in healthy individuals, yet we were surprised that activity was even higher during reappraisal of, versus passive viewing of, pictures with negative emotional content in this sample of individuals with primary insomnia," Dr. Franzen commented in a conference statement.

"Although our findings are preliminary, they do suggest a link between insomnia and depression in how the brain deals with emotion," he told Medscape Medical News. "Not just how the brain responds to an emotional stimulus, but while trying to explicitly downregulate emotions through voluntary processes, and perhaps in a way similar to depression — a disorder characterized by impairments in the regulation of emotion."

Noteworthy Study

This study is "noteworthy because it may be shedding light on a very poorly understood diagnosis: primary insomnia," Christopher Winter, MD, who wasn't involved in the study, told Medscape Medical News.

"The vast majority of individuals who suffer from insomnia, suffer as a result of some underlying issue," explained Dr. Winter, medical director, Martha Jefferson Hospital Sleep Medicine Center in Charlottesville, Virginia, and member of the American Academy of Sleep Medicine.

"For example, if an individual loses their job, they may develop insomnia," he said. "Through poor coping mechanisms and treatment, this insomnia may become chronic.  Either way, this was a secondary insomnia, meaning it was the symptom of something else."

The idea of primary insomnia is different, Dr. Winter noted. "It basically proposes that there are underlying neurological abnormalities in these individuals that prevent them from sleeping well. This study addresses a proposed mechanism for this type of insomnia and works towards establishing the mechanism and how it might relate to the depression that is often seen in these patients," Dr. Winter said.

He believes the team's observations have both clinical and research implications. "Perhaps in the future, functional MRI scans could be utilized to help differentiate this primary insomnia from more common forms of insomnia. This would have direct implications as to the kinds of therapy employed to help these individuals. Given that primary insomnia is often lifelong, this research may help lead to earlier detection and intervention with these patients," Dr. Winter said.

Dr. Franzen said among the next research steps is to see whether treatment of insomnia will regularize abnormalities in the neural circuitry underlying emotion regulation. "If so, this would further justify treatment of insomnia to help prevent depression for developing," Dr. Franzen told Medscape Medical News.

The authors and Dr. Winter have disclosed no relevant financial relationships.

SLEEP 2013: Associated Professional Sleep Societies 27th Annual Meeting. Abstract: 0560. Presented June 5, 2013.


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