Sex-specific association between infant caudate volumes and a polygenic risk score for major depressive disorder

Depressive symptoms during the transition to adolescence: Left hippocampal volume as a marker of social context sensitivity

The transition to adolescence is a critical period for mental health development. Socio-experiential environments play an important role in the emergence of depressive symptoms with some adolescents showing more sensitivity to social contexts than others. Drawing on recent developmental neuroscience advances, we examined whether hippocampal volume amplifies social context effects in the transition to adolescence. We analyzed 2-y longitudinal data from the Adolescent Brain Cognitive Development (ABCD®) study in a diverse sample of 11,832 youth (mean age: 9.914 y; range: 8.917 to 11.083 y; 47.8% girls) from 21 sites across the United States. Socio-experiential environments (i.e., family conflict, primary caregiver's depressive symptoms, parental warmth, peer victimization, and prosocial school environment), hippocampal volume, and a wide range of demographic characteristics were measured at baseline. Youth's symptoms of major depressive disorder were assessed at both baseline and 2 y later. Multilevel mixed-effects linear regression analyses showed that negative social environments (i.e., family conflict, primary caregiver's depressive symptoms, and peer victimization) and the absence of positive social environments (i.e., parental warmth and prosocial school environment) predicted greater increases in youth's depressive symptoms over 2 y. Importantly, left hippocampal volume amplified social context effects such that youth with larger left hippocampal volume experienced greater increases in depressive symptoms in more negative and less positive social environments. Consistent with brain-environment interaction models of mental health, these findings underscore the importance of families, peers, and schools in the development of depression during the transition to adolescence and show how neural structure amplifies social context sensitivity.

Windows of Opportunity: How Age and Sex Shape the Influence of Prenatal Depression on the Child Brain

Maternal prenatal depression can affect child brain and behavioral development. Specifically, altered limbic network structure and function is a likely mechanism through which prenatal depression impacts the life-long mental health of exposed children. While developmental trajectories are influenced by many factors that exacerbate risk or promote resiliency, the role of child age and sex in the relationship between prenatal depression and the child brain remains unclear. Here, we review studies of associations between prenatal depression and brain structure and function, with a focus on the role of age and sex in these relationships. After exposure to maternal prenatal depression, altered amygdala, hippocampal, and frontal cortical structure, as well as changes in functional and structural connectivity within the limbic network, are evident during the fetal, infant, preschool, childhood, and adolescent stages of development. Sex appears to play a key role in this relationship, with evidence of differential findings particularly in infants, with males showing smaller and females larger hippocampal and amygdala volumes following prenatal depression. Longitudinal studies in this area have only begun to emerge within the last 5 years and will be key to understanding critical windows of opportunity. Future research focused on the role of age and sex in this relationship is essential to further inform screening, policy, and interventions for children exposed to prenatal depression, interrupt the intergenerational transmission of depression, and ultimately support healthy brain development.

Insight into brain sex differences of typically developed infants and brain pathologies: A systematic review

The continually advancing landscape of neuroscientific and imaging research has broadened our comprehension of sex differences encoded in the human brain, expanding from the hypothalamus and sexual behaviour to encompass the entire brain, including its diverse lobes, structures, and functions. However, less is known about sex differences in the brains of neonates and infants, despite their relevance to various sex-linked diseases that develop early in life. In this review, we provide a synopsis of the literature evidence on sex differences in the brains of neonates and infants at the morphological, structural and network levels. We also briefly overview the present evidence on the sex bias in some brain disorders affecting infants and neonates.

The effect of prenatal maternal distress on offspring brain development: A systematic review

BACKGROUND

Prenatal maternal distress can negatively affect pregnancy outcomes, yet its impact on the offspring's brain structure and function remains unclear. This systematic review summarizes the available literature on the relationship between prenatal maternal distress and brain development in fetuses and infants up to 12 months of age.

METHODS

We searched Central, Embase, MEDLINE, PsycINFO, and PSYNDEXplus for studies published between database inception and December 2023. Studies were included if prenatal maternal anxiety, stress, and/or depression was assessed, neuroimaging was used to examine the offspring, and the offspring's brain was imaged within the first year of life. The quality of the included studies was evaluated using the Quality Assessment of Diagnostic Accuracy Studies-II.

RESULTS

Out of the 1516 studies retrieved, 71 met our inclusion criteria. Although the studies varied greatly in their methodology, the results generally pointed to structural and functional aberrations in the limbic system, prefrontal cortex, and insula in fetuses and infants prenatally exposed to maternal distress.

CONCLUSIONS

The hippocampus, amygdala, and prefrontal cortex have a high density of glucocorticoid receptors, which play a key role in adapting to stressors and maintaining stress-related homeostasis. We thus conclude that in utero exposure to maternal distress prompts these brain regions to adapt by undergoing structural and functional changes, with the consequence that these alterations increase the risk for developing a neuropsychiatric illness later on. Future research should investigate the effect of providing psychological support for pregnant women on the offspring's early brain development.

Genetic Influences on the Developing Young Brain and Risk for Neuropsychiatric Disorders

Imaging genetics provides an opportunity to discern associations between genetic variants and brain imaging phenotypes. Historically, the field has focused on adults and adolescents; very few imaging genetics studies have focused on brain development in infancy and early childhood (from birth to age 6 years). This is an important knowledge gap because developmental changes in the brain during the prenatal and early postnatal period are regulated by dynamic gene expression patterns that likely play an important role in establishing an individual's risk for later psychiatric illness and neurodevelopmental disabilities. In this review, we summarize findings from imaging genetics studies spanning from early infancy to early childhood, with a focus on studies examining genetic risk for neuropsychiatric disorders. We also introduce the Organization for Imaging Genomics in Infancy (ORIGINs), a working group of the ENIGMA (Enhancing NeuroImaging Genetics through Meta-Analysis) consortium, which was established to facilitate large-scale imaging genetics studies in infancy and early childhood.

Polygenic risk for neuroticism is associated with externalizing symptoms in 2-year-old boys

Recent advances in genome-wide association studies have enabled the estimation of genetic risk of complex traits, including neuroticism, with polygenic risk scores (PRS). Neuroticism PRS has been associated with psychiatric disorders and symptoms in adults, but studies in children are scarce. We studied whether neuroticism PRS, and its subscales, worry PRS and depressive affect PRS, were associated with externalizing and internalizing symptoms in 2-year-olds. We also examined parental neuroticism PRSs' association with children's externalizing and internalizing symptoms and whether parental depressive symptoms mediated the effect. Participants from two Finnish birth cohorts, CHILD-SLEEP and FinnBrain Birth Cohort Study, who had DNA and data on Brief Infant-Toddler Social and Emotional Assessment (BITSEA) available were included in the study (N = 806 and N = 987, respectively). PRSs were calculated based on GWAS data from UK Biobank. Child's neuroticism PRS, and its subscale worry PRS, were positively associated with externalizing symptoms in 2-year-old boys, but not in girls. Mother's depressive symptoms mediated the association between maternal neuroticism PRS and externalizing and internalizing symptoms in boys, but not in girls. Our results suggest that neuroticism PRS, and its subscale worry PRS, are associated with externalizing symptoms in already as young as 2-year-old boys, and, that subclinical symptoms of maternal depression that are based on genetic disposition, have an effect on boy's internalizing and externalizing symptoms. As we did not find any associations in girls, our study supports the suggestion that girls and boys may differ in how genetic and environmental factors contribute to their development.

Mapping gene by early life stress interactions on child subcortical brain structures: A genome-wide prospective study

Background

Although it is well-established that both genetics and the environment influence brain development, they are typically examined separately. Here, we aimed to prospectively investigate the interactive effects of genetic variants-from a genome-wide approach-and early life stress (ELS) on child subcortical brain structures, and their association with subsequent mental health problems.

Method

Primary analyses were conducted using data from the Generation R Study (N = 2257), including genotype and cumulative prenatal and postnatal ELS scores (encompassing life events, contextual risk, parental risk, interpersonal risk, direct victimisation). Neuroimaging data were collected at age 10 years, including intracranial and subcortical brain volumes (accumbens, amygdala, caudate, hippocampus, pallidum, putamen, thalamus). Genome-wide association and genome-wide-by-environment interaction analyses (GWEIS, run separately for prenatal/postnatal ELS) were conducted for eight brain outcomes (i.e., 24 genome-wide analyses) in the Generation R Study (discovery). Polygenic scores (PGS) using the resulting weights were calculated in an independent (target) cohort (adolescent brain cognitive development Study; N = 10,751), to validate associations with corresponding subcortical volumes and examine links to later mother-reported internalising and externalising problems.

Results

One GWEIS-prenatal stress locus was associated with caudate volume (rs139505895, mapping onto PRSS12 and NDST3) and two GWEIS-postnatal stress loci with the accumbens (rs2397823 and rs3130008, mapping onto CUTA, SYNGAP1, and TABP). Functional annotation revealed that these genes play a role in neuronal plasticity and synaptic function, and have been implicated in neuro-developmental phenotypes, for example, intellectual disability, autism, and schizophrenia. None of these associations survived a more stringent correction for multiple testing across all analysis sets. In the validation sample, all PGSgenotype were associated with their respective brain volumes, but no PGSGxE associated with any subcortical volume. None of the PGS associated with internalising or externalising problems.

Conclusions

This study lends novel suggestive insights into gene-environment interplay on the developing brain as well as pointing to promising candidate loci for future replication and mechanistic studies.

Subcortical brain volumes in young infants exposed to antenatal maternal depression: Findings from a South African birth cohort

BACKGROUND

Several studies have reported enlarged amygdala and smaller hippocampus volumes in children and adolescents exposed to maternal depression. It is unclear whether similar volumetric differences are detectable in the infants' first weeks of life, following exposure in utero. We investigated subcortical volumes in 2-to-6 week old infants exposed to antenatal maternal depression (AMD) from a South African birth cohort.

METHODS

AMD was measured with the Beck Depression Inventory 2nd edition (BDI-II) at 28-32 weeks gestation. T2-weighted structural images were acquired during natural sleep on a 3T Siemens Allegra scanner. Subcortical regions were segmented based on the University of North Carolina neonatal brain atlas. Volumetric estimates were compared between AMD-exposed (BDI-II ⩾ 20) and unexposed (BDI-II < 14) infants, adjusted for age, sex and total intracranial volume using analysis of covariance.

RESULTS

Larger volumes were observed in AMD-exposed (N = 49) compared to unexposed infants (N = 75) for the right amygdala (1.93% difference, p = 0.039) and bilateral caudate nucleus (left: 5.79% difference, p = 0.001; right: 6.09% difference, p < 0.001). A significant AMD-by-sex interaction was found for the hippocampus (left: F(1,118) = 4.80, p = 0.030; right: F(1,118) = 5.16, p = 0.025), reflecting greater volume in AMD-exposed females (left: 5.09% difference, p = 0.001, right: 3.54% difference, p = 0.010), but not males.

CONCLUSIONS

Volumetric differences in subcortical regions can be detected in AMD-exposed infants soon after birth, suggesting structural changes may occur in utero. Female infants might exhibit volumetric changes that are not observed in male infants. The potential mechanisms underlying these early volumetric differences, and their significance for long-term child mental health, require further investigation.

Maternal depressive symptoms, neonatal white matter, and toddler social-emotional development

Maternal prenatal depression is associated with increased likelihood of neurodevelopmental and psychiatric conditions in offspring. The relationship between maternal depression and offspring outcome may be mediated by in-utero changes in brain development. Recent advances in magnetic resonance imaging (MRI) have enabled in vivo investigations of neonatal brains, minimising the effect of postnatal influences. The aim of this study was to examine associations between maternal prenatal depressive symptoms, infant white matter, and toddler behaviour. 413 mother-infant dyads enrolled in the developing Human Connectome Project. Mothers completed the Edinburgh Postnatal Depression Scale (median = 5, range = 0-28, n = 52 scores ≥ 11). Infants (n = 223 male) (median gestational age at birth = 40 weeks, range 32.14-42.29) underwent MRI (median postmenstrual age at scan = 41.29 weeks, range 36.57-44.71). Fixel-based fibre metrics (mean fibre density, fibre cross-section, and fibre density modulated by cross-section) were calculated from diffusion imaging data in the left and right uncinate fasciculi and cingulum bundle. For n = 311, internalising and externalising behaviour, and social-emotional abilities were reported at a median corrected age of 18 months (range 17-24). Statistical analysis used multiple linear regression and mediation analysis with bootstrapping. Maternal depressive symptoms were positively associated with infant fibre density in the left (B = 0.0005, p = 0.003, q = 0.027) and right (B = 0.0006, p = 0.003, q = 0.027) uncinate fasciculus, with left uncinate fasciculus fibre density, in turn, positively associated with social-emotional abilities in toddlerhood (B = 105.70, p = 0.0007, q = 0.004). In a mediation analysis, higher maternal depressive symptoms predicted toddler social-emotional difficulties (B = 0.342, t(307) = 3.003, p = 0.003), but this relationship was not mediated by fibre density in the left uncinate fasciculus (Sobel test p = 0.143, bootstrapped indirect effect = 0.035, SE = 0.02, 95% CI: [-0.01, 0.08]). There was no evidence of an association between maternal depressive and cingulum fibre properties. These findings suggest that maternal perinatal depressive symptoms are associated with neonatal uncinate fasciculi microstructure, but not fibre bundle size, and toddler behaviour.

Infant and Child MRI: A Review of Scanning Procedures

Magnetic resonance imaging (MRI) is a safe method to examine human brain. However, a typical MR scan is very sensitive to motion, and it requires the subject to lie still during the acquisition, which is a major challenge for pediatric scans. Consequently, in a clinical setting, sedation or general anesthesia is often used. In the research setting including healthy subjects anesthetics are not recommended for ethical reasons and potential longer-term harm. Here we review the methods used to prepare a child for an MRI scan, but also on the techniques and tools used during the scanning to enable a successful scan. Additionally, we critically evaluate how studies have reported the scanning procedure and success of scanning. We searched articles based on special subject headings from PubMed and identified 86 studies using brain MRI in healthy subjects between 0 and 6 years of age. Scan preparations expectedly depended on subject's age; infants and young children were scanned asleep after feeding and swaddling and older children were scanned awake. Comparing the efficiency of different procedures was difficult because of the heterogeneous reporting of the used methods and the success rates. Based on this review, we recommend more detailed reporting of scanning procedure to help find out which are the factors affecting the success of scanning. In the long term, this could help the research field to get high quality data, but also the clinical field to reduce the use of anesthetics. Finally, we introduce the protocol used in scanning 2 to 5-week-old infants in the FinnBrain Birth Cohort Study, and tips for calming neonates during the scans.