Age of puberty and Sleep duration: Observational and Mendelian randomization study

Methodological approaches, challenges, and opportunities in the application of Mendelian randomisation to lifecourse epidemiology: A systematic literature review

Diseases diagnosed in adulthood may have antecedents throughout (including prenatal) life. Gaining a better understanding of how exposures at different stages in the lifecourse influence health outcomes is key to elucidating the potential benefits of disease prevention strategies. Mendelian randomisation (MR) is increasingly used to estimate causal effects of exposures across the lifecourse on later life outcomes. This systematic literature review explores MR methods used to perform lifecourse investigations and reviews previous work that has utilised MR to elucidate the effects of factors acting at different stages of the lifecourse. We conducted searches in PubMed, Embase, Medline and MedRXiv databases. Thirteen methodological studies were identified. Four studies focused on the impact of time-varying exposures in the interpretation of "standard" MR techniques, five presented methods for repeat measures of the same exposure, and four described methodological approaches to handling multigenerational exposures. A further 127 studies presented the results of an applied research question. Over half of these estimated effects in a single generation and were largely confined to the exploration of questions regarding body composition. The remaining mostly estimated maternal effects. There is a growing body of research focused on the development and application of MR methods to address lifecourse research questions. The underlying assumptions require careful consideration and the interpretation of results rely on select conditions. Whilst we do not advocate for a particular strategy, we encourage practitioners to make informed decisions on how to approach a research question in this field with a solid understanding of the limitations present and how these may be affected by the research question, modelling approach, instrument selection, and data availability.

Longitudinal course and outcome of social jetlag in adolescents: A 1-year follow-up study of the adolescent sleep health epidemiological cohorts

The discrepancy in sleep timing between weekdays and weekends - social jetlag (SJL) - is known to negatively affect student quality of life (QOL). However, the association between social jetlag and physical/mental QOL among adolescents and the precise effect of social jetlag on depressive symptoms and daytime sleepiness remains unknown. This study investigated the longitudinal course, risk factors, and effects of social jetlag, a circadian misalignment, in a school-based cohort. The participants were 427 students (13.3 ± 0.6 years, 45.2% girls) from five junior high schools. We performed a baseline survey in 2019 and a 1-year follow-up survey in 2020. Depressive symptoms, QOL, and daytime sleepiness were assessed using the Birleson Depression Self-Rating Scale for Children, Paediatric Quality of Life Inventory, and Paediatric Daytime Sleepiness Scale. In the baseline survey, 49.6% of the students reported SJL ≥1 h, and 17.1% reported SJL ≥2 h. Among them, 37.2% and 6.8% reported persistent SJL at follow-up, respectively. New incidences of SJL ≥1 h were associated with older age, non-attainment of menarche or voice changes, and longer duration of smartphone use, whereas its persistence was associated with a later chronotype. Persistence of SJL ≥1 h and ≥2 h predicted depressive symptoms and daytime sleepiness at follow-up, whereas new incidences of SJL ≥2 h predicted lower QOL. In conclusion, social jetlag has a persistent course, and daytime functioning can deteriorate as social jetlag becomes chronic. Our findings suggest the need for intensive interventions for social jetlag among adolescents.

Influence of the typology and timing of childhood trauma in psychoticism

PURPOSE

Child maltreatment (CM) is associated with psychosis; however little is known about the frequency, type, and timing of abuse in the personality pathology domain of psychoticism (PSY) in the DSM-5. The purpose of this study was to analyze childhood trauma typology and frequency according to gender and to identify sensitive periods of susceptibility to CM in women with high PSY.

METHODS

The Maltreatment and Abuse Chronology Exposure (MACE) scale was used to evaluate the frequency, severity and timing of each type of maltreatment. The full sample consisted of 83 participants with different psychiatric diagnoses. Psychoticism was assessed with the DSM-5 Personality Inventory (PID-5). To identify the differences in CM exposure between the PSY+ (high psychoticism) and PSY- (low psychoticism) groups, the Mann-Whitney U test, the chi square test and random forest (RF) test were used.

RESULTS

Comparing PSY + and PSY-, revealed gender differences in the impact of abuse, with highly frequent and severe types of abuse, in women. In women, PSY + and PSY-, were differentiated especially in non-verbal emotional abuse, peer physical bullying and parental verbal abuse. Several periods with a major peak at age seven followed by peaks at age 17 and 12 years old were identified.

CONCLUSION

Increased exposure to CM occurs in women with PSY+. A sensitivity to CM exposure during early childhood and late adolescence could be a risk factor for psychoticism in women.

Sleep deprivation alters pubertal timing in humans and rats: the role of the gut microbiome

STUDY OBJECTIVES

Evidence implied that sleeping duration is associated with the timing of puberty and that sleep deprivation triggers early pubertal onset in adolescents. Sleep deprivation can affect metabolic changes and gut microbiota composition. This study investigated the effects of sleep deprivation on pubertal onset and gut microbiota composition in animal models and a human cohort.

METHODS

This study comprised 459 boys and 959 girls from the Taiwan Pubertal Longitudinal Study. Sleep duration was evaluated using the self-report Pittsburgh Sleep Quality Index questionnaire. Early sexual maturation was defined by pediatric endocrinologist assessments. Mediation analyses were done to examine the association between sleep parameters, obesity, and early sexual maturation. Besides, Sprague Dawley juvenile rats were exposed to 4 weeks of chronic sleep deprivation. Vaginal opening (VO) and preputial separation (PS) were observed every morning to determine pubertal onset in female and male rats.

RESULTS

The sleep-deprived juvenile rats in the sleep-deprived-female (SDF) and sleep-deprived-male (SDM) groups experienced delayed VO (mean VO days: 33 days in control; 35 days in SDF; p-value < 0.05) and PS (mean PS days: 42 days in control; 45 days in SDM; p-value < 0.05), respectively. Relative to their non-sleep-deprived counterparts, the sleep-deprived juvenile rats exhibited lower body weight and body fat percentage. Significant differences in relative bacterial abundance at genus levels and decreased fecal short-chain-fatty-acid levels were identified in both the SDF and SDM groups. In the human cohort, insufficient sleep increased the risk of early sexual maturation, particularly in girls (OR, 1.44; 95% CI: 1.09 to 1.89; p-value < 0.01). Insufficient sleep also indirectly affected early sexual maturation in girls, with obesity serving as the mediator.

CONCLUSIONS

Overall, sleep deprivation altered the timing of puberty in both animal and human models but in different directions. In the rat model, sleep deprivation delayed the pubertal onset in juvenile rats through gut dysbiosis and metabolic changes, leading to a low body weight and body fat percentage. In the human model, sleep deprivation led to fat accumulation, causing obesity in girls, which increased the risk of early puberty.

Advances in circadian clock regulation of reproduction

The mammalian circadian clock is an endogenously regulated oscillator that is synchronized with solar time and cycle within a 24-h period. The circadian clock exists not only in the suprachiasmatic nucleus (SCN) of the hypothalamus, a central pacemaker of the circadian clock system, but also in numerous peripheral tissues known as peripheral circadian oscillators. The SCN and peripheral circadian oscillators mutually orchestrate the diurnal rhythms of various physiological and behavioral processes in a hierarchical manner. In the past two decades, peripheral circadian oscillators have been identified and their function has been determined in the mammalian reproductive system and its related endocrine glands, including the hypothalamus, pituitary gland, ovaries, testes, uterus, mammary glands, and prostate gland. Increasing evidence indicates that both the SCN and peripheral circadian oscillators play discrete roles in coordinating reproductive processes and optimizing fertility in mammals. The present study reviews recent evidence on circadian clock regulation of reproductive function in the hypothalamic-pituitary-gonadal axis and reproductive system. Additionally, we elucidate the effects of chronodisruption (as a result of, for example, shift work, jet lag, disrupted eating patterns, and sleep disorders) on mammalian reproductive performance from multiple aspects. Finally, we propose potential behavioral changes or pharmaceutical strategies for the prevention and treatment of reproductive disorders from the perspective of chronomedicine. Conclusively, this review will outline recent evidence on circadian clock regulation of reproduction, providing novel perspectives on the role of the circadian clock in maintaining normal reproductive functions and in diseases that negatively affect fertility.

Mechanism of leptin-NPY on the onset of puberty in male offspring rats after androgen intervention during pregnancy

OBJECTIVES

The time of onset of puberty has been increasingly earlier, but its mechanism is still unclear. This study aimed to reveal the mechanism of leptin and NPY in the onset of puberty in male offspring rats after androgen intervention during pregnancy.

METHODS

Eight-week-old specific pathogen-free (SPF) healthy male Sprague-Dawley (SD) rats and 16 female SD rats were selected and caged at 1:2. The pregnant rats were randomly divided into the olive oil control group (OOG) and testosterone intervention group (TG), with 8 rats in each group. Olive oil and testosterone were injected from the 15th day of pregnancy, for a total of 4 injections (15th, 17th, 19th, 21st day). After the onset of puberty, the male offspring rats were anesthetized with 2% pentobarbital sodium to collect blood by ventral aorta puncture and decapitated to peel off the hypothalamus and abdominal fat. Serum testosterone (T), free testosterone (FT), dihydrotestosterone (DHT), dehydroepiandrosterone (DHEA), sex hormone binding globulin (SHBG), and leptin were detected by ELISA, and then the free androgen index (FAI) was calculated. The mRNA levels of androgen receptor (AR), estrogen receptor α (ERα), NPY, leptinR, and NPY2R in the hypothalamus and abdominal fat were detected by RT-PCR. Protein expression levels of AR, ERα, NPY, leptinR, and NPY2R in the arcuate nucleus (ARC) of the hypothalamus were detected by immunohistochemistry.

RESULTS

The time of onset of puberty was significantly earlier in the TG than in the OOG (P< 0.05) and was positively correlated with body weight, body length, abdominal fat, and leptinR mRNA levels in adipose tissue in the OOG (P< 0.05), while it was positively correlated with serum DHT and DHEA concentrations and FAI and AR mRNA levels in the hypothalamus in the TG (P< 0.05). The NPY2R mRNA level and protein expression levels of ERα, NPY2R, and leptinR in the TG were significantly higher than those in the OOG, while the protein expression levels of AR and NPY in the TG were significantly lower than those in the OOG (P< 0.05).

CONCLUSIONS

Testosterone intervention during pregnancy led to an earlier onset of puberty in male offspring rats, which may render the male offspring rats more sensitive to androgens, leptin, and NPY at the onset of puberty.

Association between healthy lifestyle pattern and early onset of puberty: based on a longitudinal follow-up study

The present study aimed to explore the association between healthy lifestyle pattern and childhood early onset of puberty. Based on a cohort study in Xiamen of China, a total of 1294 children was followed for three and a half years. Children's lifestyles, including dietary behaviour, physical activity, sleep duration, smoking and drinking behaviour and sedentary behaviour, were collected by questionnaires. Healthy lifestyle pattern was determined mainly according to the recommendations by the Dietary Guidelines for Chinese school-age children and Canadian Guidelines for children and youth. The pubertal development was assessed by clinical examination according to Tanner stages. The association between pre-pubertal lifestyle and early onset of puberty was estimated using linear regression and log-binomial regression. We found that children who adhered to a healthy lifestyle had a 0·36-year delay of the age of puberty onset (coef = 0·36, 95 % CI (0·08, 0·65)) and 53 % lower risk of early onset of puberty (risk ratio = 0·47, 95 % CI (0·27, 0·80)), compared with those who had a poor lifestyle. However, the beneficial effect of favourable lifestyles on the early onset of puberty was found only in boys with normal weight. Boys who adhered to active physical activity and low sedentary behaviour had a relatively delayed age of puberty onset (coef = 0·49, 95 % CI (0·26, 0·72)). This is the first time to find that healthy lifestyle pattern was associated with a substantially lower risk of early onset of puberty, especially in boys with normal weight. Advocating an integrated healthy lifestyle is essential for the development of children.

Association of body composition with pubertal timing in children and adolescents from Guangzhou, China

Objective

An ongoing debate surrounds the relationship between body composition and pubertal timing, in particular for boys. This cross-sectional study aimed to investigate the association of body composition with pubertal timing among children and adolescents.

Methods

A total of 1,493 boys and 1,261 girls who entered puberty were enrolled in Guangzhou, China. Tanner stages were evaluated by examination of breast development for girls and testicular volume for boys. Fat mass (FM) and fat-free mass (FFM) were determined by bioelectrical impedance analysis. Parameters for body composition were transformed into age-and gender-specific Z-scores. The association of body composition with pubertal timing was examined using multinomial logistic regression with inverse probability weighting (IPW) based on the propensity score.

Results

For boys, IPW analysis showed Z-scores of body fat percentage (BF%) and FM index (FMI) were negatively associated with early puberty (OR = 0.75, 95% CI = 0.64-0.87; OR = 0.74, 95% CI = 0.63-0.88). As for girls, in contrast to boys, positive associations were seen between BF% and FMI with early puberty (OR = 1.39, 95% CI = 1.19-1.64; OR = 1.59, 95% CI = 1.33-1.90). With respect to appendicular skeletal muscle mass index (ASMI), there was a positive association with early puberty and a negative one with late puberty in boys (OR = 1.26, 95% CI = 1.07-1.49; OR = 0.82, 95% CI = 0.69-0.99).

Conclusion

There is a positive association of FM with early puberty for girls while negative for boys. FFM yields a positive association with early puberty and a negative one with late puberty in boys, but not in girls. Our findings highlight the gender differences in the connection between body composition and pubertal onset.

Traumatic Brain Injury Characteristics Predictive of Subsequent Sleep-Wake Disturbances in Pediatric Patients

Simple Summary

Traumatic brain injury is a leading cause of death and disabilities in children and adolescents. Poor sleep after brain injury can slow recovery and worsen outcomes. We investigated clinical sleep problems following pediatric brain injury. We examined characteristics of the injury and details about the patients that may be risk factors for developing sleep problems. The number of patients that developed problems with their sleep after a brain injury was similar between genders. The probability of insomnia increased with increasing patient age. The probability of ‘difficulty sleeping’ was highest in 7–9 year-old brain-injured patients. Older patients had a shorter time between brain injury and sleep problems compared to younger patients. Patients with severe brain injury had the shortest time between brain injury and development of sleep problems, whereas patients with mild or moderate brain injury had comparable times between brain injury and the onset of poor sleep. Multiple characteristics of brain injury and patient details were identified as risk factors for developing sleep problems following a brain injury in children. Untreated sleep problems after a brain injury can worsen symptoms, lengthen hospital stays, and delay return to school. Identifying risk factors could improve the diagnosis, management, and treatment of sleep problems in survivors of pediatric brain injury.

Abstract

The objective of this study was to determine the prevalence of sleep-wake disturbances (SWD) following pediatric traumatic brain injury (TBI), and to examine characteristics of TBI and patient demographics that might be predictive of subsequent SWD development. This single-institution retrospective study included patients diagnosed with a TBI during 2008–2019 who also had a subsequent diagnosis of an SWD. Data were collected using ICD-9/10 codes for 207 patients and included the following: age at initial TBI, gender, TBI severity, number of TBIs diagnosed prior to SWD diagnosis, type of SWD, and time from initial TBI to SWD diagnosis. Multinomial logit and negative-binomial models were fit to investigate whether the multiple types of SWD and the time to onset of SWD following TBI could be predicted by patient variables. Distributions of SWD diagnosed after TBI were similar between genders. The probability of insomnia increased with increasing patient age. The probability of ‘difficulty sleeping’ was highest in 7–9 year-old TBI patients. Older TBI patients had shorter time to SWD onset than younger patients. Patients with severe TBI had the shortest time to SWD onset, whereas patients with mild or moderate TBI had comparable times to SWD onset. Multiple TBI characteristics and patient demographics were predictive of a subsequent SWD diagnosis in the pediatric population. This is an important step toward increasing education among providers, parents, and patients about the risk of developing SWD following TBI.

Age, Period, and Cohort Effects of Internalizing Symptoms Among US Students and the Influence of Self-Reported Frequency of Attaining 7 or More Hours of Sleep: Results From the Monitoring the Future Survey 1991-2019

Adolescent internalizing symptoms have increased since 2010, whereas adequate sleep has declined for several decades. It remains unclear how self-reported sleep attainment has affected internalizing-symptoms trends. Using 1991-2019 data from the Monitoring the Future Study (n ~ 390,000), we estimated age-period-cohort effects in adolescent internalizing symptoms (e.g., loneliness, self-esteem, self-derogation, depressive affect) and the association with yearly prevalence of a survey-assessed, self-reported measure of attaining ≥7 hours of sleep most nights. We focused our main analysis on loneliness and used median odds ratios to measure variance in loneliness associated with period differences. We observed limited signals for cohort effects and modeled only period effects. The feeling of loneliness increased by 0.83% per year; adolescents in 2019 had 0.68 (95% CI: 0.49, 0.87) increased log odds of loneliness compared with the mean, which was consistent by race/ethnicity and parental education. Girls experienced steeper increases in loneliness than boys (P < 0.0001). The period-effect median odds ratio for loneliness was 1.16 (variance = 0.09; 95% CI: 0.06, 0.17) before adjustment for self-reported frequency of getting ≥7 hours sleep versus 1.07 (variance = 0.02; 95% CI: 0.01, 0.03) after adjustment. Adolescents across cohorts are experiencing worsening internalizing symptoms. Self-reported frequency of <7 hours sleep partially explains increases in loneliness, indicating the need for feasibility trials to study the effect of increasing sleep attainment on internalizing symptoms.

Impact of sleep patterns upon female neuroendocrinology and reproductive outcomes: a comprehensive review

Sleep is vital to human bodily function. Growing evidence indicates that sleep deprivation, disruption, dysrhythmia, and disorders are associated with impaired reproductive function and poor clinical outcomes in women. These associations are largely mediated by molecular-genetic and hormonal pathways, which are crucial for the complex and time sensitive processes of hormone synthesis/secretion, folliculogenesis, ovulation, fertilization, implantation, and menstruation. Pathologic sleep patterns are closely linked to menstrual irregularity, polycystic ovarian syndrome, premature ovarian insufficiency, sub/infertility, and early pregnancy loss. Measures of success with assisted reproductive technology are also lower among women who engage in shift work, or experience sleep disruption or short sleep duration. Extremes of sleep duration, poor sleep quality, sleep disordered breathing, and shift work are also associated with several harmful conditions in pregnancy, including gestational diabetes and hypertensive disorders. While accumulating evidence implicates pathologic sleep patterns in impaired reproductive function and poor reproductive outcomes, additional research is needed to determine causality and propose therapeutic interventions.