Sensitive period-regulating genetic pathways and exposure to adversity shape risk for depression

ASMT determines gut microbiota and increases neurobehavioral adaptability to exercise in female mice

N-acetylserotonin O-methyltransferase (ASMT) is responsible for melatonin biosynthesis. The Asmt gene is located on the X chromosome, and its genetic polymorphism is associated with depression in humans. However, the underlying mechanism remains unclear. Here, we use CRISPR/Cas9 to delete 20 bp of exon 2 of Asmt, and construct C57BL/6J mouse strain with Asmt frameshift mutation (Asmtft/ft). We show that female Asmtft/ft mice exhibit anxiety- and depression-like behaviors, accompanied by an obvious structural remodeling of gut microbiota. These behavioral abnormalities are not observed in male. Moreover, female Asmtft/ft mice show a lower neurobehavioral adaptability to exercise, while wild-type shows a "higher resilience". Cross-sectional and longitudinal analysis indicates that the structure of gut microbiota in Asmtft/ft mice is less affected by exercise. These results suggests that Asmt maintains the plasticity of gut microbiota in female, thereby enhancing the neurobehavioral adaptability to exercise.

A critical period plasticity framework for the sensorimotor-association axis of cortical neurodevelopment

To understand human brain development it is necessary to describe not only the spatiotemporal patterns of neurodevelopment but also the neurobiological mechanisms that underlie them. Human neuroimaging studies have provided evidence for a hierarchical sensorimotor-to-association (S-A) axis of cortical neurodevelopment. Understanding the biological mechanisms that underlie this program of development using traditional neuroimaging approaches has been challenging. Animal models have been used to identify periods of enhanced experience-dependent plasticity - 'critical periods' - that progress along cortical hierarchies and are governed by a conserved set of neurobiological mechanisms that promote and then restrict plasticity. In this review we hypothesize that the S-A axis of cortical development in humans is partly driven by the cascading maturation of critical period plasticity mechanisms. We then describe how recent advances in in vivo neuroimaging approaches provide a promising path toward testing this hypothesis by linking signals derived from non-invasive imaging to critical period mechanisms.

Early life adversities and lifelong health outcomes: A review of the literature on large, social, long-lived nonhuman mammals

Social nonhuman animals are powerful models for studying underlying factors related to lifelong health outcomes following early life adversities (ELAs). ELAs can be linked to lifelong health outcomes depending on the species, system, sensitive developmental periods, and biological pathways. This review focuses on the literature surrounding ELAs and lifelong health outcomes in large, social, relatively long-lived nonhuman mammals including nonhuman primates, canids, hyenas, elephants, ungulates, and cetaceans. These mammals, like humans but unlike the most-studied rodent models, have longer life histories, complex social structures, larger brains, and comparable stress and reproductive physiology. Collectively, these features make them compelling models for comparative aging research. We review studies of caregiver, social, and ecological ELAs, often in tandem, in these mammals. We consider experimental and observational studies and what each has contributed to our knowledge of health across the lifespan. We demonstrate the continued and expanded need for comparative research to inform about the social determinants of health and aging in both humans and nonhuman animals.

Association of Neural Connectome With Early Experiences of Abuse in Adults

IMPORTANCE

More than 10% of children experience sexual, physical, or emotional abuse, and abuse experienced during sensitive neurodevelopmental periods is associated with a greater risk of psychiatric disorders.

OBJECTIVE

To investigate the extent to which a history of abuse is associated with alterations in the intrinsic functional connectome of the adult brain independent from the restriction of associated psychiatric conditions.

DESIGN, SETTING, AND PARTICIPANTS

This cohort study assessed data from 768 adult participants from the greater Sydney, Australia, area who were included in the study without diagnostic restrictions and categorized based on a history of childhood sexual, physical, and/or emotional abuse. Data were collected from January 1, 2009, to December 31, 2015; data analysis was performed from October 1, 2020, to March 31, 2022.

MAIN OUTCOMES AND MEASURES

Outcomes were structured psychiatric interview responses, self-report of the frequency and extent of various types of negative experiences in childhood and adolescence, and intrinsic functional connectivity derived from 5 functional magnetic resonance imaging tasks and estimated among 436 brain regions, comprising intranetwork and internetwork connectivity of 8 large-scale brain networks.

RESULTS

Among the 647 individuals with usable data (330 female [51.0%]; mean [SD] age, 33.3 [12.0] years; age range, 18.2-69.2 years), history of abuse was associated with greater likelihood of a current psychiatric illness (odds ratio, 4.55; 95% CI, 3.07-6.72; P < .001) and with greater depressive, anxiety, and stress symptoms (mean difference, 20.4; 95% CI, 16.1-24.7; P < .001). An altered connectome signature of higher connectivity within somatomotor, dorsal, and ventral attention networks and between these networks and executive control and default mode networks was observed in individuals with a history of abuse experienced during childhood (n = 127) vs those without a history of abuse (n = 442; mean difference, 0.07; 95% CI, 0.05-0.08; familywise, Bonferroni-corrected P = .01; Cohen d = 0.82) and compared with those who experienced abuse in adolescence (n = 78; mean difference, 0.06; 95% CI, 0.04-0.08]; familywise, Bonferroni-corrected P < .001; Cohen d = 0.68). Connectome alterations were not observed for those who experienced abuse in adolescence. Connectivity of this signature was transdiagnostic and independent of the nature and frequency of abuse, sex, or current symptomatic state.

CONCLUSIONS AND RELEVANCE

Findings highlight the associations of exposure to abuse before and during adolescence with the whole-brain functional connectome. The experience of child abuse was found to be associated with physiologic changes in intrinsic connectivity, independent of psychopathology, in a way that may affect functioning of systems responsible for perceptual processing and attention.

Sensitive periods in development and risk for psychiatric disorders and related endpoints: a systematic review of child maltreatment findings

Variation in the mental health of people who have experienced childhood maltreatment is substantial. One hypothesis is that this variation is attributable, in part, to the timing of maltreatment-specifically, whether maltreatment occurs during sensitive periods in development when the brain is maximally sensitive to particular types of environmental input. To determine whether there is scientific consensus around when periods of peak sensitivity occur, we did a systematic review of human observational studies. Although 89 (75%) of the 118 unique cross-sectional or longitudinal cohort studies we identified reported timing effects, no consistent sensitive periods were identified for any of the most studied outcomes. Thus, observational research on childhood maltreatment has yet to converge on a single period (or set of periods) of increased vulnerability. We identified study characteristics that might contribute to these between-study differences and used observations from our Review to suggest a comprehensive set of recommendations for future research.

Examining the epigenetic mechanisms of childhood adversity and sensitive periods: A gene set-based approach

BACKGROUND

Sensitive periods are developmental stages of heightened plasticity when life experiences, including exposure to childhood adversity, have the potential to exert more lasting impacts. Epigenetic mechanisms, including DNA methylation (DNAm), may provide a pathway through which adversity induces long-term biological changes. DNAm shifts may be more likely to occur during sensitive periods, especially within genes that regulate the timing of sensitive periods. Here, we investigated the possibility that childhood adversity during specific life stages is associated with DNAm changes in genes known to regulate the timing and duration of sensitive periods.

METHODS

Genome-wide DNAm profiles came from the Avon Longitudinal Study of Parents and Children (n = 785). We first used principal component analysis (PCA) to summarize DNAm variation across 530 CpG sites mapped to the promoters of 58 genes previously-identified as regulating sensitive periods. Gene-level DNAm summaries were calculated for genes regulating sensitive period opening (n_genes = 15), closing (n_genes = 36), and expression (n_genes = 8). We then performed linear discriminant analysis (LDA) to test associations between seven types of parent-reported, time-varying measures of exposure to childhood adversity and DNAm principal components. To our knowledge, this is the first time LDA has been applied to analyze functionally grouped DNAm data to characterize associations between an environmental exposure and epigenetic differences.

RESULTS

Suggestive evidence emerged for associations between sexual or physical abuse as well as financial hardship during middle childhood, and DNAm of genetic pathways regulating sensitive period opening and expression. However, no statistically significant associations were identified after multiple testing correction.

CONCLUSIONS

Our gene set-based method combining PCA and LDA complements epigenome-wide approaches. Although our results were largely null, these findings provide a proof-of-concept for studying time-varying exposures and gene- or pathway-level epigenetic modifications.