MedicalResearch.com Interview with:
Laura Lyall MA; MSc; PhD
Institute of Health and Wellbeing
University of Glasgow
MedicalResearch.com: What is the background for this study?
Response: Previous studies have suggested a link between disturbed circadian rhythms and depression and bipolar disorder. These studies have however usually used small samples, subjective measures of circadian disruption, or have not accounted for potential confounding factors like sociodemographic and lifestyle characteristics. The UK Biobank cohort has accelerometry (activity monitor) data as well as mental health, lifestyle, BMI and sociodemographic data for over 91,000 individuals, and means we can address this question using objective measures of circadian rhythmicity on a large scale.
We derived a measure of relative amplitude from the UK Biobank’s accelerometry data, which was recorded for 7 days between 2013-2014 from around 100,000 participants. Relative amplitude reflects the distinction, in terms of activity levels, between an individual’s most active 10 hours and least active 5 hours, in an average day. If an individual is inactive during the day, or has disturbed sleep at night, the will show low relative amplitude, consistent with disturbed circadian rest-activity patterns.
MedicalResearch.com: What are the main findings?
Response: We then examined associations between this measure and a range of mental health and wellbeing variables in a sample of 91,105 individuals. Lower relative amplitude was associated with greater risk of lifetime history of major depressive disorder and bipolar disorder, and was also associated with greater loneliness, lower self-rated happiness and health satisfaction, higher neuroticism and mood instability, and slower reaction time, a marker of cognitive ability. These associations remained after controlling for a range of sociodemographic and lifestyle characteristics, including alcohol intake, smoking, BMI and childhood trauma.
MedicalResearch.com: What should readers take away from your report?
Response: We provide evidence that relative amplitude, an objective, accelerometry-derived measure of disturbed circadian rest-activity patterns, is associated with adverse mental health and wellbeing outcomes, in a sample of over 91,000 individuals. The findings are consistent with previous suggestions that circadian disruption is a core feature of mood disorders. Novel findings that circadian disruption is also associated with a number of wellbeing and personality risk factors for mood disorder (e.g., neuroticism, loneliness) are consistent with the idea that lower relative amplitude may be associated with greater vulnerability to mood disorder.
This was however a cross-sectional, observational study and so we are not able to infer causality – we can’t tell if circadian disruption leads to mood disorder or lower subjective wellbeing or vice versa.
MedicalResearch.com: What recommendations do you have for future research as a result of this work?
Response: To more clearly address the question of causality, longitudinal studies in which accelerometry, lifestyle, mental health and wellbeing data is collected from the same individuals at several timepoints would be useful. This might allow us to examine, for example, whether lower relative amplitude of rest-activity rhythms can reliably predict onset of episodes of depression or mania. Genetic analysis including mendelian randomisation studies may also help establish whether circadian disruption is causally linked to poorer mental health and wellbeing.
Lyall L, et al “Association of disrupted circadian rhythmicity with mood disorders, subjective wellbeing, and cognitive function: A cross-sectional study of 91 105 participants from the UK Biobank” Lancet Psychiatry 2018; DOI: 10.1016/ S2215-0366(18)30139-1.
Association of disrupted circadian rhythmicity with mood disorders, subjective wellbeing, and cognitive function: a cross-sectional study of 91 105 participants from the UK Biobank
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