In the first study of its kind, a team of international scientists have identified a dozen inherited traits related to sleep, wake, and activity cycles that are associated with severe bipolar disorder.
The researchers, who were from the University of Texas Southwestern Medical Center and UCLA, also were able to tie the traits to specific chromosomes, providing important clues to the genetic nature of the disorder, as well as potential new avenues for prevention and treatment.
“We were able to identify 13 sleep and activity measures, most of which are inherited, that correlated with whether an individual had bipolar disorder. In addition, we were able to trace some of these traits to a specific chromosome,” said Dr. Joseph Takahashi, Chairman of Neuroscience at UT Southwestern.
“This study represents a key step in identifying the genetic roots of this disorder and, in turn, providing targets for new approaches to preventing and treating bipolar disorder,” said Dr. Nelson Freimer, who directs the Center for Neurobehavioral Genetics and holds the Maggie Gilbert Chair of Psychiatry at UCLA.
Bipolar disorder, or manic-depressive illness, causes dramatic mood shifts – often called episodes – in which the person is overly excited, extremely sad or depressed, or a mixed state of both, including irritable or explosive behavior, according to the National Institute of Mental Health, part of the National Institutes of Health.
Causes of bipolar disorder (BP) are thought to be both genetic and environmental, and researchers have long suspected that disruption in normal daily circadian rhythms, including sleep and wake cycles, can precede mood shifts.
Researchers here found that those with bipolar disorder awoke later and slept longer, on average were awake fewer minutes overall, and were active for shorter periods than those without the disorder. Researchers also found that those with bipolar disorder displayed lower activity levels while awake and had greater variations in sleep and wake cycles. The findings are reported in the journal Proceedings of the National Academy of Sciences.
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