Brainstem volume mediates seasonal variation in depressive symptoms: A cross sectional study in the UK Biobank cohort

Abstract

Seasonal differences in mood and depressive symptoms affect a large percentage of the general population, with seasonal affective disorder (SAD) representing the most common presentation. SAD affects up to 3% of the world's population, and it tends to be more predominant in females than males. The brainstem has been shown to be affected by photoperiodic changes, and that longer photoperiods are associated with higher neuronal density and decreased depressive-like behaviours. We predict that longer photoperiod days are associated with larger brainstem volumes and lower depressive scores, and that brainstem volume mediates the seasonality of depressive symptoms. Participants (N = 9289, 51.8% females and 48.1% males) ranging in age from 44 to 79 years were scanned by MRI at a single location. Photoperiod was found to be negatively correlated with low mood and anhedonia in females while photoperiod was found to be positively correlated with brainstem volumes. In females, whole brainstem, pons and medulla volumes individually mediated the relationship between photoperiod and both anhedonia and low mood, while midbrain volume mediated the relationship between photoperiod and anhedonia. No mediation effects were seen in males. Our study extends the understanding of the neurobiological factors that contribute to the pathophysiology of seasonal mood variations.

Circadian Rhythms of the Hypothalamus: From Function to Physiology

“…The VTA is not the only non-hypothalamic region recently uncovered for its rhythmic role in emotion. In schizophrenia, which is characterized by psychotic behaviors, transcript analysis in post-mortem brain tissues schizophrenia patients reveal altered rhythmic gene expression in the dorsolateral prefrontal cortex [ 330 ]. The hypothalamic region is still likely involved in schizophrenia as other studies have found increases in hypothalamic volume [ 350 ] and attenuated AVP mRNA expression in the hypothalamus [ 351 ].…”

Incidence rate and clinical characteristics of seasonal affective disorders in senior medical students

“…Majrashi и соавт. [18] обнаружена отрицательная корреляция длины светового периода с плохим настроением и ангедонией у женщин. У мужчин не наблюдалось никаких опосредованных эффектов.…”

Amygdala and subregion volumes are associated with photoperiod and seasonal depressive symptoms: A cross‐sectional study in the UK Biobank cohort

“…There is evidence showing the impact of changes in environmental factors such as photoperiod on brain morphology. Recent previous studies (Majrashi, Ahearn, & Waiter, 2020; Majrashi, Ahearn, Williams, & Waiter, 2020; Miller et al, 2015) have found that photoperiod (day length) is positively associated with the volume of brain regions such as the hippocampus and brainstem substructures and that individuals exposed to longer photoperiod days exhibited larger hippocampal and brainstem substructure volumes compared with those exposed to shorter photoperiod days. The amygdala, a region responsible for emotion, cognition and social behaviours (Pessoa, 2010), has also been shown to be affected by seasonal differences in photoperiod in animals (Romeo & Sisk, 2001).…”

“…In humans, seasonal morphological differences in brain volume, particularly the brainstem, have been implicated in seasonal depressive symptoms. Brainstem volume was found to mediate the relationship between seasonal differences in photoperiod and depressive symptoms, including low mood and anhedonia, in females but not in males (Majrashi, Ahearn, & Waiter, 2020). In light of the importance of the amygdala to mood regulation and the lack of research linking seasonal variations in photoperiod to seasonal variations in mood and amygdala volume, the aims of this study were to (a) test the seasonal pattern of amygdala and subregion volumes; (b) explore whether photoperiod is associated with amygdala and subregion volume, as well as depressive symptoms; and if so, (c) explore whether the effect of photoperiod on mood might be mediated by seasonal variations in amygdala morphology.…”