Subjective insomnia symptoms and sleep duration are not related to hypothalamic-pituitary-adrenal axis activity in older adults

Causal Relationship Between Sleep Traits and Hypothalamic-Pituitary-Target Gland Axis Function: A Mendelian Randomization Study

Background

In recent years, multiple observational studies have confirmed the association between sleep traits and various human physiopathological states. However, the causal relationship between sleep traits and hypothalamic-pituitary-target gland axis (HPTGA) function remains unknown.

Methods

We obtained summary statistics on sleep traits (insomnia, chronotype, and sleep duration (long and short)) from the UK Biobank database. Data related to the HPTGA functions were obtained from the publicly available database. Subsequently, a two-sample Mendelian randomization (MR) analysis was performed to investigate the causal relationship between different sleep traits and the HPTGA function. Reverse MR analysis was conducted to examine the direction of causality.

Results

The MR analysis results suggested that chronotype is associated with decreased levels of six hormones in HPTGA. Sleep duration was causally associated with decreased levels of free thyroxine and progesterone. Both long and short sleep durations are detrimental to the secretion of prolactin-releasing peptide, somatostatin, and plasma cortisol, while short sleep duration can promote progesterone secretion. After gender stratification, we found that female reproductive function is more susceptible to the influence of unfavorable sleep traits.

Conclusion

Our MR analysis indicated a significant causal association between chronotype and suppressed gonadal function in healthy adult humans, with no apparent gender-specific effect. Extreme sleep durations were also found to be detrimental to the maintenance of normal HPTGA secretion function. Compared to males, gonadal function in the female cohort is more susceptible to extreme sleep habits. Subsequent observational studies are urgently needed to confirm the underlying mechanisms.

Depression in Older Adults: Do Current DSM Diagnostic Criteria Really Fit?

OBJECTIVES

The great heterogeneity in symptoms and clinical signs of depression in older adults makes the current diagnostic criteria difficult to apply. This scoping review aims to provide an update on the relevance of each of the diagnostic criteria as defined in the DSM-5.

METHODS

In order to limit the risk of bias inherent in the study selection process, a priori inclusion and exclusion criteria were defined. Articles meeting these criteria were identified using a combination of search terms entered into PubMed, PsycINFO, PsycARTICLES and SocINDEX.

RESULTS

Of the 894 articles identified, 33 articles were selected. This review highlights a different presentation of depression in older adults. Beyond the first two DSM core criteria, some symptoms are more common in older adults: appetite change, sleep disturbance, psychomotor slowing, difficulty concentrating, indecisiveness, and fatigue.

CONCLUSIONS

This review provides an updated description of the clinical expression of depressive symptoms in the older population while highlighting current pending issues.

CLINICAL IMPLICATIONS

Somatic symptoms should be systematically considered in order to improve the diagnosis of depression in older adults, even if, in some cases, they may reflect symptoms of age-related illnesses.

The potential of biomarkers for diagnosing insomnia: Consensus statement of the WFSBP Task Force on Sleep Disorders

OBJECTIVES

Thus far, the diagnosis of insomnia is based on purely clinical criteria. Although a broad range of altered physiological parameters has been identified in insomniacs, the evidence to establish their diagnostic usefulness is very limited. Purpose of this WFSBP Task Force consensus paper is to systematically evaluate a series of biomarkers as potential diagnostic tools for insomnia.

METHODS

A newly created grading system was used for assessing the validity of various measurements in establishing the diagnosis of insomnia; these measurements originated from relevant studies selected and reviewed by experts.

RESULTS

The measurements with the highest diagnostic performance were those derived from psychometric instruments. Biological measurements which emerged as potentially useful diagnostic instruments were polysomnography-derived cyclic alternating pattern, actigraphy, and BDNF levels, followed by heart rate around sleep onset, deficient melatonin rhythm, and certain neuroimaging patterns (mainly for the activity of frontal and pre-frontal cortex, hippocampus and basal ganglia); yet, these findings need replication, as well as establishment of commonly accepted methodology and diagnostic cut-off points. Routine polysomnography, EEG spectral analysis, heart rate variability, skin conductance, thermoregulation, oxygen consumption, HPA axis, and inflammation indices were not shown to be of satisfactory diagnostic value.

CONCLUSIONS

Apart from psychometric instruments which are confirmed to be the gold standard in diagnosing insomnia, six biomarkers emerge as being potentially useful for this purpose.

Epigenetics: A missing link between early life stress and depression

Research has suggested a relationship between early life stress, and depression in particular longer episodes of depression with treatment resistant outcomes. However, the underlying mechanisms for this association remain poorly understood. Molecular studies indicate that, in general, the hereditary character of psychiatric disorders are polygenic, multifactorial and highly complex, with innumerable low-effect genetic variants interacting with each other. In addition, the importance of the environment and its interaction with genes has pointed to a fundamental role of epigenetic mechanisms in psychiatric disorders, such as methylation of deoxyribonucleic acid (DNA), alterations, histone actions and regulation of gene expression by non-coding ribonucleic acids (RNAs). This article provides an overview of the interplay of epigenetics, the HPA axis, early life stress and the development of depression. Advances in our knowledge of epigenetics in the context of early life stress and depression provide a new understanding of the genetic influence on psychopathology and could lead to the identification of new targets for clinical intervention.

Jiaotai Pill () Alleviates Insomnia through Regulating Monoamine and Organic Cation Transporters in Rats

OBJECTIVE

To reveal the effect and mechanism of Jiaotai Pill (, JTP) on insomniac rats.

METHODS

The insomniac model was established by intraperitoneal injection of p-chlorophenylalanine (PCPA). In behavioral experiments, rats were divided into control, insomniac model, JTP [3.3 g/(kg•d)], and diazepam [4 mg/(kg•d)] groups. The treatment effect of JTP was evaluated by weight measurement (increasement of body weight), open field test (number of crossings) and forced swimming test (immobility time). A high performance liquid chromatography-electrochemical detection (HPLC-ECD) method was built to determine the concentration of monoamine transmitters in hypothalamus and peripheral organs from normal, model, JTP, citalopram [30 mg/(kg•d)], maprotiline [40 mg/(kg•d)] and bupropion [40 mg/(kg•d)] groups. Expressions of serotonin transporter (SERT), dopamine transporter (DAT), and norepinephrine transporter (NET) were analyzed by quantitative polymerase chain reaction (qPCR) and Western blot in normal, model and JTP groups. A high performance liquid chromatography-electrospray ionization mass spectrometry (HPLC-ESI-MS/MS) method was established to determine the pharmacokinetics, urine cumulative excretion of metformin in vivo, and tissue slice uptake in vitro, which were applied to assess the activity of organic cation transporters (OCTs) in hypothalamus and peripheral organs.

RESULTS

Compared with the insomniac model group, the body weight and spontaneous locomotor were increased, and the immobility time was decreased after treatment with JTP (P<0.01). Both serotonin and dopamine contents in hypothalamus and peripheral organs were increased (P<0.01). The norepinephrine content was increased in peripheral organs and decreased in hypothalamus (P<0.05 or P<0.01). At the same time, SERT, DAT, OCT1, OCT2, and OCT3 were down-regulated in hypothalamus and peripheral organs (P<0.05). NET was down-regulated in peripheral organs and up-regulated in hypothalamus (P<0.05 or P<0.01). Moreover, the activity of OCTs in hypothalamus and peripheral organs was inhibited (P<0.05).

CONCLUSION

JTP alleviates insomnia through regulation of monoaminergic system and OCTs in hypothalamus and peripheral organs.

Metabolic syndrome is associated with better quality of sleep in the oldest old: results from the "Mugello Study"

BACKGROUND AND AIMS

Reduced sleep quality is common in advanced age. Poor sleep quality is associated with adverse outcomes, chiefly cardiovascular, in young and middle-aged subjects, possibly because of its association with metabolic syndrome (MetS). However, the correlates of sleep quality in oldest populations are unknown. We evaluated the association of sleep quality with MetS in a cohort of subjects aged 90+.

METHODS AND RESULTS

We analysed data of 343 subjects aged 90+ living in the Mugello area (Tuscany, Italy). Quality of sleep was assessed using the Pittsburgh Sleep Quality Assessment Index (PSQI). Good quality of sleep was defined by a PSQI score < 5. MetS was diagnosed according to the National Cholesterol Education Program's ATP-III criteria; 83 (24%) participants reported good quality of sleep. MetS was diagnosed in 110 (24%) participants. In linear and logistic models, MetS was inversely associated with PSQI score ((B = - 1.04; 95% CI - 2.06 to - .03; P = .044), with increased probability of good sleep quality (OR = 2.52; 95% CI 1.26-5.02; P = .009), and with a PSQI below the median (OR = 2.11; 95% CI 1.11-3.40, P = .022), after adjusting. None of the single components of MetS were associated with PSQI (all P values > .050). However, an increasing number of MetS components was associated with increasing probability of good quality of sleep (P for trend = .002), and of PSQI below the median (P for trend = .007). Generalized Additive Model analysis documented no smoothing function suggestive of nonlinear association between PSQI and MetS.

CONCLUSION

Our results confirm a high prevalence of poor sleep quality in oldest age; however, in these subjects, MetS seems to be associated with better sleep quality. Additional larger, dedicated studies are required to confirm our results, and, if so, to identify the subsystems involved and the potential therapeutic implications of such an association.

The paradox of paradoxical insomnia: A theoretical review towards a unifying evidence-based definition

Paradoxical insomnia is one of the most intriguing yet challenging subtypes of insomnia. Despite being recognized for a long time by the international community, it is still unclear whether this entity really exists, which are its features and boundaries. Much of the debate is fuelled by the lack of a consensus on its precise definition. To help filling some of the existing gaps, a systematic review of the literature was conducted, through which 19 different quantitative definitions were obtained. These definitions were then applied to two distinct datasets. The first consisted of 200 chronic primary insomnia patients, diagnosed according to the DSM-IV-TR criteria. The second consisted of 200 age- and sex-matched healthy persons without insomnia. For each dataset, available data from the objective sleep parameters and their subjective estimation were imported and analysed in MATLAB. Depending on the definition used, the prevalence of paradoxical insomnia ranged from 8 to 66%, while agreement between different definitions ranged from -0.19 to 0.9 (using Cohen's kappa coefficient). Based on the results garnered, necessary features for a quantitative definition of paradoxical insomnia were identified. Several open questions remain, such as whether there is a minimum number of hours a patient should sleep to fulfill the criteria for a diagnosis of paradoxical insomnia, and whether sleep latency can be used in the definition along with total sleep time. We conclude by advocating continued study of paradoxical insomnia and sleep state misperception and by providing specific directions for future research. STATEMENT OF SIGNIFICANCE: The current understanding of paradoxical insomnia and, more broadly, of sleep state misperception, is greatly hampered by the lack of agreement on a quantitative and evidence-base measure of the discrepancy between subjective and objective sleep evaluation. The current study provides a critical analysis about the strength and the limitations of the available definitions, using both a data-driven and a theory-driven approach. The overarching goal is to motivate a rigorous discussion involving the main experts of the field, to build a consensus, and develop an evidence-based measure of sleep state misperception and/or of paradoxical insomnia.