Chronotype, Longitudinal Volumetric Brain Variations Throughout Adolescence, and Depressive Symptom Development

The subjective amplitude of the diurnal rhythm matters - Chronobiological insights for neuroimaging studies

Multiple aspects of human psychophysiology, including mood and cognition, are subjected to diurnal rhythms. While the previous magnetic resonance imaging (MRI) studies have focused solely on the morningness-eveningness (ME) preference dichotomy, i.e. the circadian phase, the second key dimension of the diurnal rhythms, i.e. the strength of these preferences (amplitude; AM), has been completely overlooked. Uncovering the neural correlates of AM is especially important considering its link with negative emotionality. Structural T1-weighted neuroimaging data from 79 early (EC) and 74 late (LC) chronotypes were analysed to compare grey matter (GM) volume and cortical thickness. The study aimed to elucidate whether the subjective AM and its interaction with ME was a significant predictor of individual brain structure. Both GM volume and cortical thickness of the left primary visual cortex was negatively correlated with AM scores across the entire sample. Furthermore, EC and LC differed in their association between AM scores and the GM volume in the right middle temporal gyrus, with the positive and negative correlations reported respectively in the two groups. The current study underlines the importance of the visual system in circadian rhythmicity and provides possible neural correlates for AM-related differences in negative affect processing. Furthermore, the presence of the opposite correlations between brain anatomy and AM in the two groups suggests that the behavioural and neuronal chronotype differences might become more pronounced in individuals with extreme diurnal differences in mood and cognition, highlighting the necessity to additionally account for AM in neuroimaging studies.

Commentary: Advancing our understanding of the sleep-circadian pas de deux for adolescent psychopathology - a reflection on Cooper et al. (2023)

This is an exciting time for research in sleep and psychopathology during the period of adolescence. The study by Cooper et al. (Journal of Child Psychology and Psychiatry, 2023) is a much-welcome addition to a rapidly accumulating body of work, examining change in eveningness preference throughout adolescence and its prediction of internalizing and externalizing psychopathology. The study has a number of strengths, including a four-wave longitudinal design, multi-informant ratings of psychopathology, and an examination of white matter development in a subsample of participants. This commentary discusses the study's strengths and findings, while also providing directions for future research to build on the target article.