3.2 childhood maltreatment’s impact on brain development

How does the brain’s plasticity change over time and what factors contribute to this change?

Brain plasticity is highly pronounced during early sensitive or critical periods, shaped by experiences. While not entirely lost, plasticity diminishes with time due to molecular “brakes” that can be influenced by factors like pharmacological interventions or epigenetic modifications

What is the central hypothesis explored in the Teicher et al (2016) review concerning the effects of maltreatment on brain development?

The review investigates the hypothesis that childhood maltreatment, acting as a stressor, triggers physiological and neurohormonal responses that alter brain development, thereby increase if the risk of psychiatric symptoms in genetically susceptible individuals

Describe the potential adaptive value of altered auditory cortex and accurate fasciculus integrity in individuals exposed to parental verbal abuse

The heightened sensitivity to auditory stimuli and altered language processing associated with these changes could be adaptive by making individuals more attuned to potential threats in their environment, particularly in the form of verbal aggression

How do the findings on visual cortex alterations in individuals who witnessed domestic violence align with the concept of experience dependent plasticity?

The reduced volume and thickness in visual cortex regions, specifically those involved in processing emotionally salient visual information, suggest that the brain adapts to recurrent exposure to visual threats, potentially prioritising processing of such stimuli

Explain the proposed “threat detection and response circuit” and how it is impacted by maltreatment.

The “threat detection and response circuit” encompasses regions like the amygdala, hippocampus, prefrontal cortex, and sensory cortices responsible for identifying and reacting to perceived threats. Maltreatment is linked to structural and functional changes in this circuit, potentially leading to hyper-reactivity to perceived threats

Why might findings on amygdala volume in maltreated individuals be inconsistent?

The inconsistency likely arises from the fact that early life stress may initially enlarge the amygdala but simultaneously increase its sensitivity to subsequent stressors, leading to a gradual reduction in volume over time.

What is the relationship between maltreatment and the reward anticipation response in the brain?

Maltreatment is consistently associated with a diminished BOLD response in striatal regions, particularly the ventral striatum, during reward anticipation. This blunted response may contribute to depression and increased vulnerability to substance abuse.

Describe the proposed link between corpus collosum alterations and “black and white” thinking in individuals with a history of maltreatment

The observed reduced thickness and altered microstructure in the corpus callosum, a structure facilitating inter-hemispheric communication, might contribute to the less integrated hemispheric activity observed in maltreated individuals. This lateralisation is suggested to potentially underlie the “black and white” thinking characteristic of borderline personality disorder, acting as a coping mechanism in environments with inconsistent caregiving.

How does the concept of “ecophenotype” apply to the study of mental illness in the context of childhood maltreatment?

The concept of “ecophenotype” acknowledges that the same psychiatric diagnosis can manifest differently depending on the environmental factors like maltreatment. It proposes that maltreated individuals with a particular diagnosis constitute a distinct subtype with unique clinical and neurobiological features.

Explain the concept of resilience in the context of maltreatment and its potential neurobiological underpinnings

Resilience refers to the ability of some maltreated individuals to avoid developing psychopathology despite experiencing neurobiological alterations. This may be due to compensatory brain differences, such as increased connectivity in certain regions, that mitigate the negative effects of maltreatment.

Polymorphisms:

Variations in DNA sequence that can influence individual susceptibility to environmental influences

Epigenetics:

Changes in gene expression that are not caused by alterations in DNA sequence, often influenced by environmental factors.

Default Mode Network (DMN):

A network of brain regions that is active during rest and mind-wandering.

Graph Theory:

A mathematical approach used to analyze networks, including brain networks, by representing them as nodes (brain regions) and edges (connections).

Fractional Anisotropy (FA):

A measure of white matter integrity reflecting the organization and coherence of nerve fibers.

Tract-Based Spatial Statistics (TBSS):

A neuroimaging technique used to analyze white matter pathways in the brain.

Voxel-Based Morphometry (VBM):

A neuroimaging technique used to assess differences in brain volume between groups.

Resilience:

The ability to withstand stress and adversity without developing mental health problems.

Ecophenotype:

A subtype of a disorder that arises from specific environmental influences, such as maltreatment.

Reward Anticipation:

The brain's response to the expectation of a reward, often measured in the striatum.

Threat Detection and Response Circuit:

A network of brain regions involved in identifying and responding to threats, including the amygdala, hippocampus, prefrontal cortex, and sensory cortices.

Sensory Systems:

Systems responsible for processing information from the senses, such as vision, hearing, and touch.

Plastic-Adaptation Hypothesis:

The idea that brain changes observed in response to stress, including maltreatment, might be adaptive and serve to enhance survival in a threatening environment.

Diathesis-Stress Model:

A model proposing that mental disorders arise from a combination of genetic predisposition (diathesis) and environmental stressors.

Stress:

A physiological and psychological response to challenging or threatening situations.

Maltreatment:

Physical, sexual, or emotional abuse or neglect experienced during childhood.

Experience-Dependent Plasticity:

Brain changes that occur in response to specific experiences.

Resilience vs. Susceptibility:

Brain abnormalities associated with maltreatment are not always linked to psychopathology. Some individuals demonstrate resilience despite these alterations, possibly due to compensatory mechanisms in the brain.

Sensory System Specificity:

Maltreatment impacts sensory cortices corresponding to the type of abuse experienced:

○Verbal abuse affects the auditory cortex and arcuate fasciculus.

○Witnessing domestic violence impacts the visual cortex and inferior longitudinal fasciculus.

○Sexual abuse affects visual areas involved in facial recognition and somatosensory areas representing the genitals.

Network Architecture Changes:

Maltreatment affects overall brain network architecture, notably reducing centrality in areas associated with emotional regulation, attention, and social cognition (ACC, temporal pole, middle frontal gyrus), while increasing centrality in regions related to self-awareness (insula and precuneus).

Maltreatment as a Confounding Variable:

Reduced hippocampal volume is commonly linked to depression but appears primarily driven by the maltreated subtype. This highlights the need to control for maltreatment history in psychiatric neuroimaging studies.

Implications for Research and Practice:

●Future research should focus on longitudinal studies with larger sample sizes, controlling for confounding variables like socioeconomic status and genetics.

●Translational studies in animal models are crucial to establish causality and explore the underlying mechanisms.

●Investigating the neurobiological underpinnings of resilience can inform interventions aimed at enhancing adaptive coping mechanisms.

●Differentiating ecophenotypic variants within psychiatric diagnoses is essential for tailoring treatment approaches and improving outcomes.