Sleep and psychiatric disorders

Women's mood at high altitude. sexual dimorphism in hypoxic stress modulation by the tryptophan-melatonin axis

Sexual (and gender)-dimorphism in tolerance to hypobaric hypoxia increasingly matters for a differential surveillance of human activities at high altitude (HA). At low altitudes, the prevalence of anxiety and depression in women has already been found to double when compared with men; it could be expected to even increase on exposure to HA. In purposefully caring for the health of women at HA, the present work explores the potential involvement of the tryptophan (Trp)-melatonin axis in mood changes on exposure to hypobaric hypoxia. The present work highlights some already known anxiogenic effects of HA exposure. Hypoxia and insomnia reduce serotonin (5-HT) availability; the latter defect being expressed as failure of brown adipose tissue (BAT) activation and mood disorders. Rapid eye movement (REM) sleep organization and synapsis restoration that are additionally affected by hypoxia impair memory consolidation. Affective complaints may thus surge, evolving into anxiety and depression. Sex-related differences in neural network organization and hormonal changes during the menstrual cycle, and certainly also during the life cycle, underscore the possibility of 5-HT-related mood alterations, particularly in women on HA exposure. The mean brain rate of 5-HT synthesis at sea level is already 1.5-fold higher in males than in females. sexual dimorphism also evidences the overexpression effects of SERT, a 5-HT transporter protein. Gonadal and thyroid hormones, as influenced by HA exposure, further modulate 5-HT availability and its effects in women. Besides caring for adequate oxygenation and maintenance of one's body core temperature, special precautions concerning women sojourning at HA should include close observations of hormonal cycles and, perhaps, also trials with targeted antidepressants.

Association of Rapid Eye Movement Sleep With Mortality in Middle-aged and Older Adults

Importance

Rapid eye movement (REM) sleep has been linked with health outcomes, but little is known about the relationship between REM sleep and mortality.

Objective

To investigate whether REM sleep is associated with greater risk of mortality in 2 independent cohorts and to explore whether another sleep stage could be driving the findings.

Design, Setting, and Participants

This multicenter population-based cross-sectional study used data from the Outcomes of Sleep Disorders in Older Men (MrOS) Sleep Study and Wisconsin Sleep Cohort (WSC). MrOS participants were recruited from December 2003 to March 2005, and WSC began in 1988. MrOS and WSC participants who had REM sleep and mortality data were included. Analysis began May 2018 and ended December 2019.

Main Outcomes and Measures

All-cause and cause-specific mortality confirmed with death certificates.

Results

The MrOS cohort included 2675 individuals (2675 men [100%]; mean [SD] age, 76.3 [5.5] years) and was followed up for a median (interquartile range) of 12.1 (7.8-13.2) years. The WSC cohort included 1386 individuals (753 men [54.3%]; mean [SD] age, 51.5 [8.5] years) and was followed up for a median (interquartile range) of 20.8 (17.9-22.4) years. MrOS participants had a 13% higher mortality rate for every 5% reduction in REM sleep (percentage REM sleep SD = 6.6%) after adjusting for multiple demographic, sleep, and health covariates (age-adjusted hazard ratio, 1.12; fully adjusted hazard ratio, 1.13; 95% CI, 1.08-1.19). Results were similar for cardiovascular and other causes of death. Possible threshold effects were seen on the Kaplan-Meier curves, particularly for cancer; individuals with less than 15% REM sleep had a higher mortality rate compared with individuals with 15% or more for each mortality outcome with odds ratios ranging from 1.20 to 1.35. Findings were replicated in the WSC cohort despite younger age, inclusion of women, and longer follow-up (hazard ratio, 1.17; 95% CI, 1.03-1.34). A random forest model identified REM sleep as the most important sleep stage associated with survival.

Conclusions and Relevance

Decreased percentage REM sleep was associated with greater risk of all-cause, cardiovascular, and other noncancer-related mortality in 2 independent cohorts.

Depression, mitochondrial bioenergetics, and electroconvulsive therapy: a new approach towards personalized medicine in psychiatric treatment - a short review and current perspective

Major depressive disorder (MDD) is a globally occurring phenomenon and developed into a severe socio-economic challenge. Despite decades of research, the underlying pathophysiological processes of MDD remain incompletely resolved. Like other mental disorders, MDD is hypothesized to mainly affect the central nervous system (CNS). An increasing body of research indicates MDD to also change somatic functioning, which impairs the physiological performance of the whole organism. As a consequence, a paradigm shift seems reasonable towards a systemic view of how MDD affects the body. The same applies to treatment strategies, which mainly focus on the CNS. One new approach highlights changes in the bioenergetic supply and intracellular network dynamics of mitochondria for the pathophysiological understanding of MDD. Mitochondria, organelles of mostly all eukaryotic cells, use carbon compounds to provide biochemical energy in terms of adenosine triphosphate (ATP). ATP is the bioenergetic currency and the main driver for enzymatic activity in all cells and tissues. Clinical symptoms of MDD including fatigue, difficulties concentrating, and lack of motivation were reported to be associated with impaired mitochondrial ATP production and changes in the density of the mitochondrial network. Additionally, the severity of these symptoms correlates negatively with mitochondrial functioning. Psychotherapy, antidepressant medication, and electroconvulsive therapy (ECT), a method used to treat severe and treatment-resistant forms of MDD, achieve robust antidepressant effects. The biological mechanisms beyond the treatment response to antidepressant strategies are partially understood. Here, mitochondrial functioning is discussed as a promising new biomarker for diagnosis and treatment effects in MDD.