The effect of child abuse on the brain and the impact of stress hormones on emotional and cognitive development
Maltreatment, no matter whether it is abuse, neglect, abandonment or witnessing violent acts, can lead to enduring negative changes in the still developing brain of a child. Each time there is some sort of trauma, the brain suffers a particular change. So far, researchers have noted changes in the prefrontal cortex, the cerebellum and the limbic system (Wheeler T., 2006) It is important to point out that infancy and early childhood are times for rapid brain development and formation of dendritic connections. Of course, they continue to develop throughout adolescence and early adulthood, but are particularly vulnerable earlier in life (Kalat J, 2003).
The prefrontal cortex is the most anterior part of the frontal lobe of the brain and is involved in critical thinking and judgment, as well as any behavior that depends on context and requires decision making. Therefore, people with damaged prefrontal cortex often cannot modify their behavior and become inflexible in changing situations, which can make their reactions and behavior too impulsive and socially unacceptable (Kalat J., 2003). Damage to the prefrontal cortex can eventually result in many deficits, such as not being able to regulate motivation and efforts and having impaired short-term and long-term goal-directed behavior. In addition, damage and disruption of prefrontal cortex functions due to any type of abuse may lead to being unable to integrate positive emotions. Thus, the person is stuck in a negative stance of fear, anger and anxiety, and cannot engage in experiencing positive emotions. Needless to say, this may lead to developing depression, antisocial or borderline personality disorders (Wheeler T., 2006).
The cerebellum is a large structure in the hindbrain that is mainly known for controlling movement, achieving balance and coordination (Kalat J., 2003). However, it also plays a role in attention and emotions, as well as in regulating the limbic system (Wheeler T., 2006). Multiple studies involving brain imaging have shown that many people with psychiatric disturbances have abnormalities in the cerebellum (Wheeler T., 2006). This could be explained by the fact that in incidences of childhood abuse the cerebellum is extremely vulnerable to the stress hormones that are released in large amounts during stress, trauma or abuse. The brain changes that occur subsequently can lead to depression or hyperactivity, and inattention. Also, the cerebellum is considered to play a role in suppressing irritability. Therefore, abnormalities or damage to the cerebellum may cause chronic irritability and make the person seek external means, such as drugs, to deal the subjective discomfort (Wheeler T., 2006).
The limbic system is the forebrain area next to the brainstem that includes a number of interdependent structures under the cerebral cortex, which deal with motivation and are critical in regulating emotions, sexual activity, eating, drinking, anxiety and aggression (Kalat J., 2003). The hippocampus and the amygdala are essential parts of the limbic system and are crucially important for controlling the emotional response to a particular situation. They also take part in memory formation and learning (Wheeler T., 2006). Prolonged and continuous exposure to stress hormones can cause serious damage to these parts of the limbic system and disrupt mood regulation, memory, and one’s way of interpreting the environment. Besides, damage to the limbic system can lead to epileptic seizures and abnormal EEGs that usually affect the temporal lobe of the left hemisphere. Usually, damage to the left hemisphere is associated with poor verbal development, but, more importantly, with aggression, self-destructive behavior and suicidality (Wheeler T., 2006).
What is stress? Many things can be considered stressful for an individual, including insufficient nutrition, lack of rest, overstimulation, especially of the fear-related response system, as well as abuse, neglect or witnessing violence or death (Gunnar & Vazquez, 2001). The prolonged exposure to stress and the produced stress hormones in the body can be very serious and especially harmful to infants and young children (Gunnar & Vazquez, 2001). In fact, exposure to stress activates two body systems: the autonomic nervous system that prepares the body to react quickly to stimuli in the environment and the HPA-axis – the hypothalamus, pituitary and adrenal cortex.
The HPA-axis reacts more slowly, but is critically important in prolonged exposure to stressors (Kalat J., 2003). The activation of the hypothalamus stimulates the ‘master gland’ (the pituitary gland) to secrete adrenocorticotropic hormone (ACTH) that, in turn, stimulates the secretion of cortisol. Cortisol is generally regarded as ‘The’ stress hormone. It helps the body mobilize energy and respond to stress quickly, but has negative effects in the long run, since it enhances metabolism and elevates blood sugar levels (Kalat J., 2003). Other stress-related hormones are corticosteroids, corticotrophin release hormone (CRH), epinephrine and norepinephrine (Gunnar & Vazquez, 2001). Serotonin is also very important for the adequate coping with stress. Therefore, abnormal function of serotonin is associated with some depression and anxiety-related disorder, such as BPD.
Research has shown that elevated stress hormone levels can cause malfunctions in the amygdala and hippocampus (Gunnar & Vazquez, 2001). Severe or merely constant exposure to stress may lead to the shriveling of certain dendrites in the hippocampus, which can cause its degeneration and malfunction (memory loss and inability to control the release of other stress hormones) (Gunnar & Vazquez, 2001). Shrunken hippocampus has been observed in autopsies of children who have experienced repeated abuse or in people who were suffering Post-traumatic Stress Disorder. In addition, disruption of the HPA-axis that is also related to exposure to stress in early age is associated with depression, inattention, and poor memory (Gunnar & Vazquez, 2001). The hippocampus is a particularly vulnerable brain structure, especially during infancy and childhood, when it is still developing (Gunnar & Vazquez, 2001).
If too many stress hormones are being produced in the early stages of development, the developing brain may be permanently damaged, becoming incapable of initiating a normal stress response. It may either overproduce stress hormones, so that the person becomes hyper-vigilant, fearful and always on the alert, or it may underproduce stress hormones so that the person becomes “emotionally flat”, sad and depressed (Berger, 2005). A study of Cicchetti & Rogosch (2001) identified a lot of “atypical cortisol regulation patterns” that are obvious among children that have been maltreated. Studies like this are evidence for the correlation between child maltreatment and the disrupted function of certain brain structures that cause inflexibility in behavior, such as depression, chronic stress, anxiety, aggression and many others that can often be associated with a number of illnesses and disorders.
Many of the brain abnormalities that have been studied in abused and neglected children are located in the left hemisphere. Very often, in children, victims of abuse, there were fewer dendritic connections between different areas in the left hemisphere (Gunnar & Vazquez, 2001). Children that had showed such abnormal results demonstrated self-destructive or aggressive behavior, as well as certain disturbances in thinking, emotional reactivity and physiology (higher blood pressure, heart rates, temperature, hypervigilance) (Gunnar & Vazquez, 2001). Since these could all be characteristics of a borderline personality patient, the results give food for thought as to the relation between abuse in childhood and the development of the disorder.
Studies of neglected children found that their cortex was about 20 percent smaller than that of a control group of subjects (children) who have not suffered neglect (Gunnar & Vazquez, 2001).
The negative effects of childhood abuse are real and alarming, perceived not only intuitively, but also through tangible scientific methods. Raising awareness, educating parents and engaging in careful preventative monitoring are not only the lawful obligations of doctors, teachers and helping professionals, but also the ethical obligation of any good citizen. Remember that you only need to suspect child abuse in order to call the National Child Abuse Hotline that receives anonymous calls 24/7 at 1-800-4-A-CHILD (1-800-422-4453). I believe we are all responsible for the welfare of our minors, who represent your future and the heritage we leave behind.