Study proposes circadian pattern in depression cohort

Researchers at the University of Sydney have identified a proposed circadian pattern among people with depression, classifying 2,604 of 11,380 participants in an Australian study as fitting the researchers’ criteria. The group represents about 23 percent of the cohort, which included people with severe, recurrent or persistent depression. The findings do not establish a formally recognized subtype or show that targeted treatments work better. The researchers analyzed clinical and genetic data from the Australian Genetics of Depression Study. Participants were classified under the proposed category if they reported at least three of six features linked to sleep and mood: seasonal changes in symptoms, later sleep timing, differences between sleep schedules on workdays and free days, an evening-oriented routine, sleeping longer during depression, and pronounced tiredness on waking. Compared with other participants, those meeting the criteria reported an earlier onset of depression and more severe features, including suicidal thoughts. They also reported less benefit and more side effects from common antidepressants. These treatment findings reflect participants’ past experiences,...