Healthcare (Commonwealth Union) – Scientists in Australia say they have identified a unique form of depression associated with the body’s internal clock. That may be why some patients don’t get much relief from the drugs most often prescribed first.
The University of Sydney team call it “circadian depression”. They said it accounted for nearly a quarter of the people they studied with severe, recurrent or persistent depression.
The team used data from over 10,000 Australians in the Australian Genetics of Depression Study, a national study that combined clinical information with genetic data. The circadian profile was met by 2,604 participants.
Within the group, a cluster of sleep-related features. These included a seasonal illness, sleeping longer than usual when down, waking up exhausted, and a natural tendency to stay up late.
An alternative view of the disease
Participants in the circadian group tended to get sick earlier in life and reported more severe symptoms compared to other participants. These included episodes of mania and increased suicidal ideation.
Their genetic profiles stood out, too. They also had a higher inherited risk of inflammatory and cardiovascular disease and neurodevelopmental disorders, like ADHD.
Most importantly, the group seemed to have differential response to treatment. The first line for depression is usually an antidepressant that works on serotonin, such as SSRIs and the related SNRIs. The researchers said that people with the circadian subtype often get less benefit from these drugs and are more likely to have side effects.
Treatments targeted at the body clock
The team says this group may be better served in other ways. These include light therapy, melatonin and antidepressants that act on melatonin pathways, which all interact with the brain circuits that control sleep and waking.
Clinicians should be thinking about these approaches far earlier for patients with this pattern, said Dr Jacob Crouse, a co-senior author from the university’s Brain and Mind Center. He also urged people who are not getting relief from their medication to talk to their own doctor instead of changing it themselves.
Dr Emiliana Tonini, first author of the work, indicated that the work shows that depression is not one uniform condition. Recognizing its subtypes, could help patients get the right treatment sooner.
Worry for the young
Professor Ian Hickie, co-director of the Brain and Mind Center and clinical psychiatrist, indicated that they really desired young people to get the most appropriate treatment early in their course of illness.
He further pointed out that a majority of young people will be offered SSRIs initially, however for at least 25% there are better circadian-focused medical and behavioral choices that will assit in treating and managing the condition.
Funding and disclosures
Support for the Australian Genetics of Depression Study was provided mainly by the National Health and Medical Research Council (NHMRC) and also by private donations from families affected by mental illness. Several authors were awarded NHMRC investigator grants.
The declarations in the study report that Professor Hickie has undertaken research into agomelatine, a melatonin-based anti-depressant, funded by its manufacturer, Servier. He also has a small equity stake in Innowell, a company developing digital mental health services.
Implications for patients
This is an observational study reporting trends in a large population, and does not show that any individual will respond to a particular treatment. People on antidepressants should not stop or alter them without medical advice.
If you are depressed or have thoughts of self-harm, speak to a doctor or your local crisis service.
