Researchers have identified evidence supporting a potential subtype of clinical depression, known as “circadian depression,” defined by disrupted sleep-wake patterns and associated with more severe symptoms and poorer responses to commonly prescribed antidepressants, according to a study published Oct. 20 in The British Journal of Psychiatry.
The study, led by researchers from the University of Sydney’s Brain and Mind Centre, analyzed data from 11,380 adults with depression in the Australian Genetics of Depression Study. Researchers classified participants as having a circadian subtype if they met at least three of six criteria related to sleep and circadian disruption: social jetlag, seasonality, delayed sleep midpoint, evening chronotype, morning tiredness and hypersomnia. They compared clinical characteristics, self-reported antidepressant responses and genetic risk profiles between groups.
Here are five things to know:
1. Twenty-three percent of participants met criteria for the proposed subtype. Of the 11,380 participants, 2,604 were classified as having circadian depression.
2. The subtype was associated with earlier depression onset and more severe symptoms. Participants reported an average onset age of 18.68 years, compared with 23.20 years among those without the subtype. They also reported greater psychological distress, suicidal ideation and psychotic-like experiences.
3. Participants reported poorer responses to common antidepressants. The circadian subtype was associated with lower self-reported efficacy of selective serotonin reuptake inhibitors (odds ratio 0.88) and serotonin-norepinephrine reuptake inhibitors (odds ratio 0.89), along with more side effects.
4. The subtype was associated with higher genetic risk for several conditions. Researchers identified higher genetic risk scores for major depression, bipolar disorder, anxiety and attention-deficit hyperactivity disorder, as well as metabolic and inflammatory traits.
5. Further research is needed before the subtype can guide treatment. Researchers said the findings support the potential clinical utility of circadian depression, but independent replication and additional research are needed to establish its biological basis and predictive value.
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