Seasonality of brain function: role in psychiatric disorders

Abstract

Seasonality patterns are reported in various psychiatric disorders. The current paper summarizes findings on brain adaptations associated with seasonal changes, factors that contribute to individual differences and their implications for psychiatric disorders. Changes in circadian rhythms are likely to prominently mediate these seasonal effects since light strongly entrains the internal clock modifying brain function. Inability of circadian rhythms to accommodate to seasonal changes might increase the risk for mood and behavior problems as well as worse clinical outcomes in psychiatric disorders. Understanding the mechanisms that account for inter-individual variations in seasonality is relevant to the development of individualized prevention and treatment for psychiatric disorders. Despite promising findings, seasonal effects are still understudied and only controlled as a covariate in most brain research. Rigorous neuroimaging studies with thoughtful experimental designs, powered sample sizes and high temporal resolution alongside deep characterization of the environment are needed to better understand the seasonal adaptions of the human brain as a function of age, sex, and geographic latitude and to investigate the mechanisms underlying the alterations in seasonal adaptation in psychiatric disorders.

Optimization and efficiency analysis of deep learning based brain tumor detection

“…𝐶𝑜𝑠𝑡 𝑓𝑢𝑛𝑐𝑖𝑜𝑛 = 𝐿𝑜𝑠𝑠 + 𝑅𝑒𝑔𝑢𝑙𝑎𝑟𝑖𝑧𝑎𝑡𝑖𝑜𝑛 𝑝𝑎𝑟𝑎𝑚𝑒𝑡𝑒𝑟 (1) In L2 or weight decay lambda is known as regularization term which is a hyperparameter whose value is changed for achieving improved results. It forces weight to decay not exactly zero but towards zero, as described in Eq.…”

“…One of the most complicated organs of human body is the brain which controls all the actions of human body by receiving information from different senses and send them back for performing the appropriate action [1]. An abnormality to this organ can create serious effects on the functionality of the human body, this abnormality is well known as the brain tumor [2].…”

How does the macroenvironment influence brain and behaviour – a review of current status and future perspectives

“…Furthermore, seasonal changes directly affect the duration of daylight. Seasonal daylength fluctuations appear to affect mood and behaviour negatively and were associated with a higher prevalence of seasonal affective disorder and earlier onset of bipolar disorder (201). Here it is important to acknowledge that many of these findings are susceptible to bias due to inadequate control of confounders and the risk for an ecological fallacy – the incorrect inference about individuals based on aggregated-level data associations (202).…”

“…Additionally, impairments in the FC of the DMN were observed (210), coupled with prolonged reaction time in cognitive tasks compared with the control group (209,210). A few cross-sectional studies reported positive associations between daylength and volumes of the hippocampus, amygdala, and brain-stem – regions that exhibited seasonal variations in serotonin signalling (201), suggesting that changes in volumes of subcortical regions and neurotransmitter signalling involved in emotional regulation may be involved in the seasonality of mental disorders.…”

Seasonal patterns of sickness absence due to diagnosed mental disorders: a nationwide 12-year register linkage study

“…whereas depressive episodes mostly peak in early winter, and mixed episodes peak in early spring as well as in the middle of or late in the summer (Fellinger et al, 2022;Geoffroy et al, 2014;Zhang and Volkow, 2023). Few studies have focused on anxiety, sleep and substance use disorders, although these have been associated with self-reported SAD (Palmu et al, 2022;Sandman et al, 2016).…”