Effect of cortisol diurnal rhythm on emotional memory in healthy young adults

DNA methylation in blood cells is associated with cortisol levels in offspring of mothers who had prenatal post‐traumatic stress disorder

Maternal stress during pregnancy is associated with differential DNA methylation in offspring and disrupted cortisol secretion. This study aimed to determine methylation signatures of cortisol levels in children, and whether associations differ based on maternal post-traumatic stress disorder (PTSD). Blood epigenome-wide methylation and fasting cortisol levels were measured in 118 offspring of mothers recruited from the Kosovo Rehabilitation Centre for Torture Victims. Mothers underwent clinically administered assessment for PTSD using Diagnostic and Statistical Manual of Mental Disorders. Correlations between offspring methylation and cortisol levels were examined using epigenome-wide analysis, adjusting for covariates. Subsequent analysis focussed on a priori selected genes involved in the hypothalamic-pituitary-adrenal (HPA) axis stress signalling. Methylation at four sites were correlated with cortisol levels (cg15321696, r = -0.33, cg18105800, r = +0.33, cg00986889, r = -0.25, and cg15920527, r = -0.27). In adjusted multivariable regression, when stratifying based on prenatal PTSD status, significant associations were only found for children born to mothers with prenatal PTSD (p < 0.001). Several sites within HPA axis genes were also associated with cortisol levels in the maternal PTSD group specifically. There is evidence that methylation is associated with cortisol levels, particularly in offspring born to mothers with prenatal PTSD. However, larger studies need to be carried out to independently validate these findings.

Do your troubles today seem further away than yesterday? On sleep's role in mitigating the blushing response to a reactivated embarrassing episode

The "sleep to forget and sleep to remember hypothesis" proposes that sleep weakens the emotional tone of an experience while preserving or even enhancing its content. Prior experimental research however shows contradictory findings on how emotional reactivity changes after a period of sleep, likely explained by methodological variations. By addressing these inconsistencies, we investigated the mitigating effect of overnight sleep on emotional reactivity triggered by memory reactivation. Using a karaoke paradigm, we recorded participants' singing of two songs, followed by exposing them to one of the recordings (rec1) to induce an embarrassing episode. After a 12-hr period of either day-time wakefulness (N = 20) or including nighttime sleep (N = 20), we assessed emotional reactivity to the previously exposed recording (rec1) and the newly exposed recording (rec2). Emotional reactivity was assessed with a physiological measure of facial blushing as the main outcome and subjective ratings of embarrassment and valence. Sleep and wake were monitored with diaries and actigraphy. The embarrassing episode was successfully induced as indicated by objective and subjective measures. After controlling for an order effect in stimulus presentation, we found a reduction in blushing response to the reactivated recording (rec1) from pre- to post-sleep compared to wakefulness. However, emotional reactivity to the reactivated recording (rec1) and the new recording (rec2) did not differ after sleep and wakefulness. This study shows that facial blushing was reduced following overnight sleep, while subjective ratings were unaffected. Whether the beneficial effect of sleep is due to changes in memory representation or rather emotion regulation remains elusive.

Adult Neurogenesis under Control of the Circadian System

The mammalian circadian system is a hierarchically organized system, which controls a 24-h periodicity in a wide variety of body and brain functions and physiological processes. There is increasing evidence that the circadian system modulates the complex multistep process of adult neurogenesis, which is crucial for brain plasticity. This modulatory effect may be exercised via rhythmic systemic factors including neurotransmitters, hormones and neurotrophic factors as well as rhythmic behavior and physiology or via intrinsic factors within the neural progenitor cells such as the redox state and clock genes/molecular clockwork. In this review, we discuss the role of the circadian system for adult neurogenesis at both the systemic and the cellular levels. Better understanding of the role of the circadian system in modulation of adult neurogenesis can help develop new treatment strategies to improve the cognitive deterioration associated with chronodisruption due to detrimental light regimes or neurodegenerative diseases.

Hypothalamic-Pituitary-Adrenal Axis Activity in Childhood Predicts Emotional Memory Effects and Related Neural Circuitry in Adolescent Girls

Negative emotional experiences can be more difficult to forget than neutral ones, a phenomenon termed the "emotional memory effect." Individual differences in the strength of the emotional memory effect are associated with emotional health. Thus, understanding the neurobiological underpinnings of the emotional memory effect has important implications, especially for individuals at risk for emotional health problems. Although the neural basis of emotional memory effects has been relatively well defined, less is known about how hormonal factors that can modulate emotional memory, such as glucocorticoids, relate to that neural basis. Importantly, probing the role of glucocorticoids in the stress- and emotion-sensitive period of late childhood to adolescence could provide actionable points of intervention. We addressed this gap by testing whether hypothalamic-pituitary-adrenal (HPA) axis activity during a parent-child conflict task at 11 years of age predicted emotional memory and its primary neural circuitry (i.e., amygdala-hippocampus functional connectivity) at 16 years of age in a longitudinal study of 147 girls (104 with complete data). Results showed that lower HPA axis activity predicted stronger emotional memory effects, r(124) = -.236, p < .01, and higher emotional memory-related functional connectivity between the right hippocampus and the right amygdala, β = -.385, p < .001. These findings suggest that late childhood HPA axis activity may modulate the neural circuitry of emotional memory effects in adolescence, which may confer a potential risk trajectory for emotional health among girls.