White matter changes in children and adolescents with reactive attachment disorder: A diffusion tensor imaging study

Subclinical structural atypicality of retinal thickness and its association with gray matter volume in the visual cortex of maltreated children

Childhood maltreatment is reportedly associated with atypical gray matter structures in the primary visual cortex (V1). This study explores the hypothesis that retinal structures, the sensory organs of vision, are associated with brain atypicality and child maltreatment and examines their interrelation. General ophthalmologic examinations, visual cognitive tasks, retinal imaging, and structural magnetic resonance imaging (MRI) were conducted in children and adolescents aged 9-18 years with maltreatment experiences (CM) and typically developing (TD) children. The retinal nerve fiber layer (RNFL), the most superficial of the ten distinct retinal layers, was found to be significantly thinner in both eyes in CM. While whole-brain analysis using Voxel-based morphometry revealed a significantly larger gray matter volume (GMV) in the thalamus in CM, no significant correlation with RNFL thickness was observed. However, based on region-of-interest analysis, a thinner RNFL was associated with a larger GMV in the right V1. Although it cannot be ruled out that this outcome resulted from maltreatment alone, CM demonstrated subclinical structural atypicality in the retina, which may also correlate with the immaturity of V1 development. Examination of retinal thickness offers a novel clinical approach to capturing characteristics associated with childhood maltreatment.

The neurobiological effects of childhood maltreatment on brain structure, function, and attachment

Childhood maltreatment is a risk factor for psychopathologies, and influences brain development at specific periods, particularly during early childhood and adolescence. This narrative review addresses phenotypic alterations in sensory systems associated with specific types of childhood maltreatment exposure, periods of vulnerability to the neurobiological effects of maltreatment, and the relationships between childhood maltreatment and brain structure, function, connectivity, and network architecture; psychopathology; and resilience. It also addresses neurobiological alterations associated with maternal communication and attachment disturbances, and uses laboratory-based measures during infancy and case-control studies to elucidate neurobiological alterations in reactive attachment disorders in children with maltreatment histories. Moreover, we review studies on the acute effects of oxytocin on reactive attachment disorder and maltreatment and methylation of oxytocin regulatory genes. Epigenetic changes may play a critical role in initiating or producing the atypical structural and functional brain alterations associated with childhood maltreatment. However, these changes could be reversed through psychological and pharmacological interventions, and by anticipating or preventing the emergence of brain alterations and subsequent psychopathological risks.

Diffusion tensor imaging of white-matter structural features of maltreating mothers and their associations with intergenerational chain of childhood abuse

Child abuse causes lifelong adverse outcomes for both physical and mental health, although many are resilient. Efforts to prevent this issue from the parental side require an understanding of the neurobiological basis that leads abusive parents to perpetrate abuse and the influence of the intergenerational chain of childhood abuse. Therefore, this study was conducted to compare the brain white-matter fiber structures between 11 maltreating mothers who had been recognized as having conducted child abuse prior to the intervention and 40 age-matched control mothers using tract-based spatial statistics. There was a significantly reduced axial diffusivity (AD) and a similar trend in fractional anisotropy (FA) in the right corticospinal tract in maltreating mothers compared to control mothers. Therefore, maltreating mothers may have excessive control over the forcefulness of voluntary movements. These features also decreased as the number of childhood abuse experiences increased, suggesting that an intergenerational chain of child abuse may also be involved. Other aspects observed were that the higher the current depressive symptoms, the lower the AD and FA values; however, they were not related to parental practice or empathy. These results corroborate the neurobiological features that perpetrate behaviors in abusive mothers.

The impact of out-of-home care on brain development: a brief review of the neuroscientific evidence informing our understanding of children's attachment outcomes

Researchers interested in the effects of early experiences of caregiving adversity have employed neuroscientific methods to illuminate whether and how such environmental input impacts on brain development, and whether and how such impacts underpin poor socioemotional outcomes in this population. Evidence is compelling in documenting negative effects on the individual's neurodevelopment following exposure to adverse or disadvantaged environments such as institutionalization or maltreatment. Neuroimaging research focused specifically on attachment-relevant processing of socioemotional stimuli and attachment outcomes among children looked-after is scarcer, but largely consistent. This review begins by summarizing the key general brain structural and functional alterations associated with caregiving deprivation. Then, neuroscientific evidence that is more directly relevant for understanding these children's attachment outcomes, both by employing social stimuli and by correlating children's neural markers with their attachment profiles, is reviewed. Brief interpretations of findings are suggested, and key limitations and gaps in the literature identified.

Early life stress impairs brain and mental development during childhood increasing the risk of developing psychiatric disorders

In recent years, it has become known that stress in childhood, called early life stress (ELS), affects the mental health of children, adolescents, and adults. Child maltreatment (CM) is an inappropriate form of childcare that interferes with children's normal brain and mind development. Previous studies have reported that CM severely affects brain development and function. For example, ELS causes brain vulnerability and increases the risk of developing psychiatric disorders. In addition, it is known that the different types and timing of abuse have different effects on the brain. Epidemiological and clinical studies are being conducted to understand the mechanism underlying abuse on a child's mental health and appropriate brain development; however, they are not fully understood. Therefore, studies using animal models, as well as humans, have been conducted to better understand the effects of CM. In this review, we discuss the effects of comparing previous findings on different types of CM in human and animal models. However, it should be noted that there are differences between animal models and humans such as genetic polymorphism and susceptibility to stress. Our review provides the latest insights into the negative effects of CM on children's development and on psychiatric disorders in adulthood.

Association of adverse childhood experience-related increase in neurite density with sensory over-responsivity in autism spectrum disorder: A neurite orientation dispersion and density imaging study

Sensory over-responsivity (SOR) causes social and daily distress in individuals with autism spectrum disorder (ASD). Compared to typically developed (TD) individuals, ASD individuals are at higher risk of adverse childhood experiences (ACEs), which induce abnormal neuronal development. However, whether or how ACEs are associated with abnormal neural development and SOR in ASD remains to be determined. Forty-five individuals with ASD and 43 TD individuals underwent T1-weighted and neurite orientation dispersion and density imaging; the axonal and dendritic densities were defined as the neurite density index (NDI). Voxel-based analyses were performed to explore the brain regions associated with SOR. The relationships between severity of ACEs and SOR, and NDI in the brain regions were examined. ASD individuals showed a significantly positive association between SOR severity and NDI in the right superior temporal gyrus (STG), which was not found in TD individuals. Severity of ACEs correlated significantly with that of SOR and NDI in the right STG in ASD; ASD individuals having severe SOR showed significantly higher NDI in the right STG than those with mild SOR and TD individuals. In individuals with ASD, NDI in the right STG, but not ACEs, could predict the severity of SOR, which was not shown in TD subjects. Our findings suggest that severe ACEs are involved in excessive neurite density in the right STG in ASD. ACE-associated excessive neurite density in the right STG is critical for SOR in ASD, which may be a therapeutic target in the future.

Review of the Current Knowledge of Reactive Attachment Disorder

Reactive attachment disorder (RAD), classified under Trauma and Stressor Related Disorders in the DSM-5 manual, is a childhood psychiatric illness due to familial or social neglect or due to maltreatment. It is characterized by an inhibited and withdrawn social and emotional behavior toward an adult caregiver, typically before the age of 5. Neurobiological changes in patients with RAD have been shown to be substantially significant with features such as loss of grey matter volume and neurotransmitter deficiencies that not only impact the ability to form healthy attachments but also increase the risk of comorbidities such as depression and anxiety. Different theories, including the current mediation hypothesis and learning theory of attachment, showed childhood maltreatment from caregivers and desensitization toward deficiencies in social development in children from special education teachers to be key components in the development of RAD. Patients with RAD had an increased risk of developing psychiatric comorbidities, including learning disabilities and mood disorders. Institutionalized care and childhood maltreatment have a significant impact on the development of RAD. RAD is an underdiagnosed and underreported condition with significant repercussions that can severely impact the development of a child. By being able to raise awareness and promote further research into refining the diagnostic methodology, treatment protocols, and long-term follow-up, children afflicted with this condition may be able to develop better socio-emotional bonds and reduce the incidence of comorbidities such as depression and attention deficit hyperactivity disorder.

Cerebellar engagement in the attachment behavioral system

Brain structural bases of individual differences in attachment are not yet fully clarified. Given the evidence of relevant cerebellar contribution to cognitive, affective, and social functions, the present research was aimed at investigating potential associations between attachment dimensions (through the Attachment Style Questionnaire, ASQ) and cerebellar macro- and micro-structural measures (Volumetric and Diffusion Tensor Imaging data). In a sample of 79 healthy subjects, cerebellar and neocortical volumetric data were correlated with ASQ scores at the voxel level within specific Regions Of Interest. Also, correlations between ASQ scores and age, years of education, anxiety and depression levels were performed to control for the effects of sociodemographic and psychological variables on neuroimaging results. Positive associations between scores of the Preoccupation with Relationships (ASQ subscale associated to insecure/anxious attachment) and cortical volume were found in the cerebellum (right lobule VI and left Crus 2) and neocortex (right medial OrbitoFrontal Cortex, OFC) regions. Cerebellar contribution to the attachment behavioral system reflects the more general cerebellar engagement in the regulation of emotional and social behaviors. Cerebellar properties of timing, prediction, and learning well integrate with OFC processing, supporting the regulation of attachment experiences. Cerebellar areas might be rightfully included in the attachment behavioral system.

Sex and sensitive period differences in potential effects of maltreatment on axial versus radial diffusivity in the corpus callosum

Corpus callosum (CC) abnormalities have been observed in several psychiatric disorders. Maltreatment has also been associated with marked differences in CC anatomy and microstructure, though rarely controlled for in psychiatric neuroimaging studies. The aim of this study was to identify type and timing of maltreatment associated with alterations in CC microstructure and to ascertain if they differ by sex. T1 and diffusion-weighted MRIs were obtained from 345 (135 M/210 F) healthy 18-25-year-olds. The Maltreatment and Abuse Chronology of Exposure scale provided retrospective data on exposure to ten types of maltreatment across each year of childhood. AI predictive analytics were used to identify the most significant type and time risk factors. The most striking maltreatment-associated alterations in males were in axial diffusivity and were most specifically associated with exposure to emotional abuse or neglect during segment-specific sensitive periods. In contrast, maltreatment was associated with marked alteration in radial diffusivity and fractional anisotropy in females and was most specifically associated with early physical neglect during one common sensitive period involving all segments except the splenium. Overall sex differences, controlling for maltreatment, brain size, and sociodemographic factors were limited to the genu with greater fractional anisotropy in males and radial diffusivity in females. These findings suggest that maltreatment may target myelinization in females and axonal development in males and that these sex differences need to be taken into account in studies seeking to delineate the contribution of CC abnormalities and interhemispheric communication to psychiatric disorders.

A multi-modal MRI analysis of brain structure and function in relation to OXT methylation in maltreated children and adolescents

Child maltreatment dysregulates the brain's oxytocinergic system, resulting in dysfunctional attachment patterns. However, how the oxytocinergic system in children who are maltreated (CM) is epigenetically affected remains unknown. We assessed differences in salivary DNA methylation of the gene encoding oxytocin (OXT) between CM (n = 24) and non-CM (n = 31), alongside its impact on brain structures and functions using multi-modal brain imaging (voxel-based morphometry, diffusion tensor imaging, and task and resting-state functional magnetic resonance imaging). We found that CM showed higher promoter methylation than non-CM, and nine CpG sites were observed to be correlated with each other and grouped into one index (OXTmi). OXTmi was significantly negatively correlated with gray matter volume (GMV) in the left superior parietal lobule (SPL), and with right putamen activation during a rewarding task, but not with white matter structures. Using a random forest regression model, we investigated the sensitive period and type of maltreatment that contributed the most to OXTmi in CM, revealing that they were 5-8 years of age and physical abuse (PA), respectively. However, the presence of PA (PA+) was meant to reflect more severe cases, such as prolonged exposure to multiple types of abuse, than the absence of PA. PA+ was associated with significantly greater functional connectivity between the right putamen set as the seed and the left SPL and the left cerebellum exterior. The results suggest that OXT promoter hypermethylation may lead to the atypical development of reward and visual association structures and functions, thereby potentially worsening clinical aspects raised by traumatic experiences.