The Neurobiology of Childhood Maltreatment

Liana W. Shelby MA
Hawaii School of Professional Psychology, Honolulu, Hawaii
liana.shelby@gmail.com


Introduction

One area of research that has been receiving increasing focus involves the effects of abuse and neglect on the developing brain, especially during infancy and early childhood (Child Welfare Information Gateway, 2009). Children's experiences, including their interactions with other people, have a significant impact on how they react to and express themselves in different situations. Both genetic factors and life experiences are necessary for optimum brain development (Shonkoff & Phillips, 2000).
     The brain's ability to adapt to its environment is a part of normal development. All children need stimulation and nurturance for healthy development. If these are lacking (e.g., if a child's caretakers are indifferent or hostile) the child's brain development may be impaired. Researchers believe that there are sensitive periods for development of certain capabilities (CWIG, 2009). These refer to periods of time in the developmental process when certain parts of the brain may be most susceptible to particular experiences. If a child's caregivers are unresponsive or threatening, and the attachment process is disrupted, the child's ability to form any healthy relationships during his or her life may be impaired (Perry, 2000a).
     The organizing framework for children's development is based on the creation of memories (CWIG, 2009). When repeated experiences strengthen a neuronal pathway, the pathway becomes encoded, and it eventually becomes a memory. If the early environment is abusive or neglectful, brains will create memories of these experiences that may adversely color children's view of the world throughout their life. Sometimes, children who have been abused or suffered other trauma may not retain or be able to access explicit memories for their experiences (CWIG, 2009). However, they may retain implicit memories of the physical or emotional sensations, and these implicit memories may produce flashbacks, nightmares, or other uncontrollable reactions (Applegate & Shapiro, 2005).
     This literature review studies how the brain develops from infancy through adolescence, and the subsequent effects of this maltreatment on brain development. Further, the psychopathology associated with childhood maltreatment, the neurobiological mechanisms, and the cognitive consequences are described.


Effects of Maltreatment on Brain Development
Abuse

Physical abuse can cause direct damage to a baby's or child's developing brain (CWIG, 2009). In the long-term, shaking can damage the fragile brain so that a child develops a range of sensory impairments, as well as cognitive, learning, and behavioral disabilities. Further, children who experience the stress of abuse will focus their brain's resources on survival and responding to threats in their environment. This chronic stimulation of the brain's fear response means that the regions of the brain involved in this response are frequently activated (Perry, 2000a). Other regions of the brain, such as those involved in complex thought and abstract cognition, are less frequently activated, and the child becomes less competent at processing this type of information. Early maltreatment experiences may alter a child's brain neuro-chemical balance which subsequently alters their ability to interact positively with others (CWIG, 2009). Additionally, altered brain development in children who have been maltreated may be the result of their brains adapting to their negative environment (CWIG, 2009). The result may be a child who has difficulty functioning when presented with a world of kindness, nurturing, and stimulation.

Neglect

Malnutrition, a classic example of neglect, both before and during the first few years after birth, can result in stunted brain growth and slower passage of electrical signals in the brain (Shonkoff & Phillips, 2000). This is due, in part, to the negative effect of malnutrition on the myelination process in the developing brain (Zero To Three, 2009). The most common form of malnutrition in the United States, iron deficiency, can affect the growing brain and result in cognitive and motor delays, anxiety, depression, social problems, and attention problems (Shonkoff & Phillips, 2000).  For children to master developmental tasks, they need opportunities, encouragement, and acknowledgment from their caregivers. If this stimulation is lacking during children’s early years, the weak neuronal pathways that had been developed in expectation of these experiences may wither and die, and the children may not achieve the usual developmental milestones.

Global Neglect

Researchers use the term “global neglect” to refer to deprivations in more than one domain, (i.e., language, touch, and interaction with others; CWIG, 2009). One study found that these children had significantly smaller brains than the norm, suggesting decreased brain growth (Perry, 2001).  The extreme lack of stimulation may result in fewer neuronal pathways available for learning. The lack of opportunity to form an attachment with a nurturing caregiver during infancy may mean that some of these children will always have difficulties forming meaningful relationships with others (Perry, 2001).

Impact of abuse and neglect on adolescents

For adolescents who have experienced abuse, neglect or trauma, this impulsive behavior may be even more apparent (CWIG, 2009). Often, these youth have developed brains that focus on survival, at the expense of the more advanced thinking that happens in the brain’s cortex (Chamberlain, 2009). An underdeveloped cortex can lead to increased impulsive behavior, as well as difficulties with tasks that require higher-level thinking and feeling. These teens may show delays in school and in social skills as well (Chamberlain, 2009).

Psychopathology

Physical, sexual, and psychological childhood abuse may lead to psychiatric difficulties which may appear in childhood, adolescence, or adulthood (Teicher, 2000).   These difficulties can be directed inward to foster symptoms of depression, anxiety, suicidal ideation, and post-traumatic stress or be directed outward as aggression, impulsiveness, delinquency, hyperactivity, and substance abuse.  Childhood abuse may lead to a range of persistent psychiatric disorders such as somatoform disorder or agoraphobia (Teicher, 2000).  More complex, difficult-to-treat disorders correlated with childhood maltreatment are borderline personality disorder, dissociative identity disorder, and eating disorders.  Children may also experience PTSD, ADHD, and reactive attachment disorder.

Discussion

Children who experience maltreatment typically have chemical imbalances in the brain due to over stimulation or under stimulation various areas of the brain during these critical periods.  The results of these chemical imbalances are a variety of disorders which can manifest in childhood, adolescence, or adulthood.  The four symptoms that serve as a basis for these difficulties are persistent fear response, hyper-arousal, dissociation, ad disrupted attachment processes.

Persistent fear response

Chronic stress or repeated traumas can result in a number of biological reactions, including a persistent fear state (Perry, 2006). Neuro-chemical systems are affected, which can cause a cascade of changes in attention, impulse control, sleep, and fine motor control (Perry, 2000a; 2000b). Chronic activation of the neuronal pathways involved in the fear response can create permanent memories that shape the child’s perception of and response to the environment. 

Hyper-arousal

Hyper-arousal can occur when children are exposed to chronic, traumatic stress and their brains sensitize the pathways for the fear response and create memories that automatically trigger that response without conscious thought (CWIG, 2009). These trauma-exposed children have an altered baseline for arousal, and they tend to overreact to triggers that other children find non-threatening. Consumed with a need to monitor nonverbal cues for threats, their brains are less able to interpret and respond to verbal cues, even when they are in a supposedly non-threatening environment, like a classroom. While these children are often labeled as learning disabled, the reality is that their brains have developed so that they are constantly alert and are unable to achieve the relative calm necessary for learning.

Dissociation

Dissociation may be a reaction to childhood sexual abuse, as well as other kinds of active, physical abuse or trauma.  This type of response may have implications for the child’s memory creation and retention (CWIG, 2009). The brain may use dissociation to smother the memories of a parent’s abuse in order to preserve an attachment to the parent, resulting in amnesia for the abuse (Stien & Kendall, 2004). However, the implicit memories of the abuse remain, and the child may experience them in response to triggers or as flashbacks or nightmares. In its most extreme form, the child may develop multiple personalities, known as dissociative identity disorder.

Disrupted attachment process

Disrupted attachment may lead to impairments in three major areas for the developing child (Cook et al., 2005): increased susceptibility to stress; excessive help-seeking and dependency or excessive social isolation; and an inability to regulate emotions.  Young infants depend on positive interactions with caregivers to begin to develop appropriate emotional control and response (affect regulation) (Applegate & Shapiro, 2005).  Infants whose caregivers are neglectful or abusive may experience affect dysregulation which means that these children are not able to identify and respond appropriately to emotional cues (Applegate & Shapiro, 2005).  These children may have difficulties forming attachments later in life as well.

Specific long-term effects of abuse and neglect on the developing brain can include diminished growth in the left hemisphere, which may increase the risk for depression (Teicher, 2000).  It may also include irritability in the limbic system, setting the stage for the emergence of panic disorder and posttraumatic stress disorder.  Further, it chronic maltreatment may lead to smaller growth in the hippocampus and limbic abnormalities, which can increase the risk for dissociative disorders and memory impairments.  Finally, childhood abuse can result in impairment in the connection between the two brain hemispheres, which has been linked to symptoms of attention deficit/ hyperactivity disorder.  Other emotional and behavioral impacts include: persistent fear response; hyper-arousal; dissociation; and disrupted attachment process.

References

Applegate, J. S., & Shapiro, J. R. (2005). Neurobiology for clinical social work theory and practice. New York: W. W. Norton & Company.

Child Abuse Prevention and Treatment Act (CAPTA) as amended by Keeping Children and Families Safe Act of 2003, 42 U.S.C. § 5106(g) (2003).

Child Welfare Information Gateway. (2009). Understanding the effects of maltreatment on brain development. Washington, DC: U.S. Department of Health and Human Services. Retrieved from www.childwelfare.gov/pubs/issue_briefs/brain_development/

Cook, A., Spinazzola, J., Ford, J., Lanktree, C., Blaustein, M., Sprague, C., et al. (2005). Complex trauma in children and adolescents. Psychiatric Annals, 35(5), 390- 398.

Perry, B. D. (2000a). The neuroarcheology of childhood maltreatment: The neurodevelopmental costs of adverse childhood events. Child Trauma Academy. Retrieved from www.childtrauma. rg/ctamaterials/Neuroarcheology.asp

Perry, B.D. (2000b). Traumatized children: How childhood trauma influences brain development. Child Trauma Academy. Retrieved from www. childtrauma.org/CTAMATERIALS/trau_CAMI.asp

Perry, B. D. (2001). The neurodevelopmental impact of violence in childhood. In D. Schetky & E. Benedek (Eds.), Textbook of child and adolescent forensic psychiatry (pp. 221-238). Washington, DC: American Psychiatric Press.

Perry, B. D. (2006). Applying principles of neurodevelopment to clinical work with maltreated and traumatized children: The neurosequential model of therapeutics. In N. B. Webb (Ed.), Working with traumatized youth in child welfare (pp. 27-52). New York: The Guilford Press.

Shonkoff, J. P., & Phillips, D. A. (2000). From neurons to neighborhoods: The science of early childhood  development. Washington, D.C.: National Academy Press. Stien & Kendall, 2004.

Stien, P. T., & Kendall, J. (2004). Psychological trauma and the developing brain:  Neurologically based interventions for troubled children. New York: The Haworth Maltreatment and Trauma Press.

Teicher, M.D. (2000). Wounds that time won’t heal: The neurobiology of child abuse. Cerebrum: The Dana Forum on brain science, 2(4), 50-67.

ZERO TO THREE. (2009). Brain development: Frequently asked questions. Retrieved from www.zerotothree.org/site/ PageServer?pagename=ter_key_brainFAQ

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