An Australian study has linked a pattern of sleep and seasonal symptoms with an earlier start to depression. People meeting the researchers’ proposed criteria reported that their illness began earlier and that they had more severe symptoms than the comparison group. The British Journal of Psychiatry (source, opens in new tab)The British Journal of PsychiatryClinical and genetic correlates of a circadian subtype of depression in the Australian Genetics of Depression StudyOpen source (opens in new tab)
The researchers call the pattern a proposed ‘circadian’ subtype, after the body’s roughly 24-hour system for regulating sleep and waking. They used reported symptoms and habits rather than direct measurements of biological clocks. The question is whether recognising this pattern could eventually help tailor assessment and treatment.
The analysis covered 11,380 people with depression who had information on at least three of the features being assessed. Of these, 2,604 — 23% — met the proposed criteria. All participants were part of the Australian Genetics of Depression Study. This was a selected study group, so the percentage should not be read as an estimate for everyone with depression.
Participants qualified if they met at least three of six criteria: different sleep times on workdays and free days, known as social jetlag; seasonal variation; a later sleep midpoint, the halfway point between falling asleep and waking; a preference for evenings; morning tiredness; and sleeping much more than usual during their worst depressive episode.
The proposed group reported lower effectiveness for two antidepressant classes: selective serotonin reuptake inhibitors (SSRIs) and serotonin–noradrenaline reuptake inhibitors (SNRIs). The same association was not found for two other antidepressants, mirtazapine and amitriptyline. These findings reflect participants’ own accounts of treatment effectiveness. The group also reported more medication side-effects.
The study, published in The British Journal of Psychiatry, analysed self-reported information collected at one point in time and was limited to people of genetically inferred European ancestry. It cannot establish cause and effect.
The proposed grouping needs independent replication. For now, the study does not establish that this symptom pattern can guide the choice of an antidepressant. It offers a lead for investigating whether differences in the experience of depression could eventually help guide care.
- The British Journal of Psychiatry · Peer-reviewed studyClinical and genetic correlates of a circadian subtype of depression in the Australian Genetics of Depression Studycambridge.org · opens in new tab
