People with depression show disrupted brain 'clock'

Gene activity in the brains of depressed people fail to follow healthy 24-hour cycles, according to a new study published in Monday’s journal Proceedings of the National Academy of Sciences. Through comparing post-mortem brain samples from mentally healthy donors and those of people who had major depression at the time of their death, researchers found that people with clinical depression show disrupted circadian rhythms across brain regions. In healthy people, of the 16 genes that showed the clearest patterns of cycling, 11 genes cycled around the clock in four or more brain regions. By contrast, in people with major depression, only two of these genes showed clear cycling pattern in more than one region, and none cycled in more than three regions. "They seem to have the sleep cycle both shifted and disrupted," said study researcher Jun Li, a professor of human genetics at the University of Michigan. "They seem to be sleeping at the wrong time of the day, and the quality of their sleep is also different from healthy sleep." The researchers found that the sleep-cycle shift which was held in patients who had a diagnosis of major depression but who had not taken antidepressants before death suggests that it's the disease itself and not the treatment that caused the circadian rhythm problems. Already, symptoms of insomnia and excessive sleep in depressed people have inspired treatments such as light therapy to try to reset the body clock, Li said. The research is confirmation that such light therapy approaches could work and drug might be developed to fix the brain clock, he said.