Neurobiologic system effects

Scientific research has provided considerable evidence involving the destructive effects of chronic child maltreatment that permanently alter brain maturation and interfere with its normal structural formation and function.9,11 These damaging consequences influence the capacity to regulate cognition, emotion, and behavior.10 There are four essential and vulnerable stages in brain development: early childhood (15 months-4 years), late childhood (6-10 years), puberty, and adolescence.10 Any significant or prolonged environmental disruption that occurs during these stages will ultimately produce harmful neurobiologic results. 

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A brief summary regarding some of the features of cerebral development includes neurogenesis, which involves the proliferation of several neural networks that provide pathways for processing information and occurs mainly in utero, with not much further development after birth.11 Neurons initially migrate to the brainstem, or lower brain, then to the cortex, or higher brain.11 This migration occurs in utero, during the perinatal period, throughout childhood, and possibly into adulthood.11 Arborization is the process of dendrite formation that assists neural activity.11 The degree of dendrite density is related to the amount and type of external input children receive while their brains are programmed to incorporate or assimilate complex stimuli.11 During synaptogenesis, the evolving neurons form axons and synapses, which enhance brain function and determine how vast the brain organizes and utilizes information.11

Differentiation involves the production of several neurotransmitters, such as dopamine, norepinephrine, serotonin, corticotropin-releasing factor, and substance P, which are released in response to stress and other emotions.10,11 The levels of these neurochemicals fluctuate widely in children reacting to a traumatic environment, affecting the neurobiologic system. In addition, response to stress affects the levels of many hormones, such as adrenalin and glucocorticoids—specifically cortisol, which is typically elevated in trauma victims.10 Consequently, the erratic production of neurochemicals and hormones may increase heart rate and gastrointestinal activity, induce chronic depression and/or anxiety, or cause immunodeficiency disease, to name only a few effects, while impairing or damaging the neuroendocrine system and various anatomical structures.10,11

A newborn’s external experience promotes “neural differentiation, arborization, and synaptogenesis,” helping to “create functional neural networks.”11 Within the first 8 months of life, synaptic density increases eightfold as neurons form proper connections, indicating that a neurobiologic susceptibility to trauma is enhanced during the first year of life.11 Stimulation of the developing brain induces neural activity and the formation of synaptic connections. When external stimuli is overly stressful, negative, or sparse, as with neglected or abused children, neurons die, and their correct placement fails and/or are displayed in a disorderly fashion (Figure 1),12 while hyper-synaptic activity occurs.10,11 

Among several essential parts of the brain, the prefrontal cortex is responsible for developing memory, controlling impulses, and allows one to learn from negative experience.10 These specific cortical functions are compromised in traumatized children who experienced elevated norepinephrine levels, due to chronic hyper-arousal states.10 In addition to decreased brain volume, a history of childhood trauma may cause deficient growth within areas of the limbic system involving the hippocampus and amygdala, also known as the “emotional brain” [within the link, see p. 111, Fig. 2].10-11 The hippocampus is susceptible to atrophy or lesser development when glucocorticoid levels are elevated in response to traumatic experience. Injury to this subcortical structure compromises the ability to control emotion and the capacity for cognitive or verbal memory.10,11 The amygdala begins to function at birth and permits an infant to sense danger, inducing the release of cortisol and adrenalin, and the ensuing fight-or-flight response.10 As a result of a traumatized upbringing, increased or persistent activation of the amygdala occurs, causing victims to miscalculate the severity of a dangerous situation or person.10 This eventually produces a general unrealistic interpretation of a victim’s environment and perceptions of oneself and others.6,10

Further explanation regarding a victim’s altered self-misconception and of his or her surroundings, is the occurrence of flashbacks, which are conscious or unconscious recollections of abuse triggered by internal or external stimuli involving “affect, vision, tactile, taste, smell, auditory, and motor systems.”9 During a flashback, victims inaccurately respond to emotions, situations, and others due to their distorted insights that confuse past trauma with present experience.1,6,9 Other compromised states of cognizance include an inability to read social cues, memory loss, hypermnesia (atypical vivid memory), and trauma-related nightmares.1 

Affect attunement is the bond between a child and his or her primary caregiver and is crucial for healthy neurobiologic development.10 It plays a critical role in helping a child learn to regulate emotion, behavior, and affect, and it determines the ability to control reactions to stress.9,10 Parental attachments are considered a gateway into a child’s inner self and character formation—the “more disorganized the parent, the more disorganized the child.”10 When these bonds are deficient, dangerous, or overwhelming, a child enters a world of irrational and inflexible responses to nominal tension and circumstances.9 In addition, fragmented relations with caregivers compromise a child’s abstract reasoning, visual-spatial skills, attention or concentration abilities, and capacity for verbal learning.1 

Any considerable disturbance that occurs during neurologic development, such as abuse, neglect, or high levels of stress or violence, will have a profound effect in the brain and lead to various types of psychopathology.11 Primarily, a child’s stage of development at the time of victimization, the degree and nature of the maltreatment, and whether the abuser is an essential caretaker are significantly correlated with the extent of cerebral injury or compromise.4,10,11 

Overall, the neurobiologic impact of DTD appears to extensively interfere with a child’s cognitive, emotional, and sensory development and performance that generally continues into adulthood.