We recently had a class discussion about Santiago Ramon y Cajal and the influence his father had on his life, based on reading from The Dreams of Santiago Ramon y Cajal by Benjamin Ehrlich. Ehrlich claims that we owe a begrudging thanks to Cajal’s father for abusing his child and forcing him into a life of science where he would have preferred pursuing his art. This caused our class to question whether Cajal would have been the genius he was without the abuse of his father, sending me on a tangent based on my experience working with maltreated and traumatized children. These children typically display severe developmental delays, which led me to sympathize with Cajal and disagree with Ehrlich’s claim. To support my stance, I decided to delve into how childhood abuse, or more broadly, trauma, affects a child’s neurobiology in both the short-term and long-term.
According to the National Center for Mental Health Promotion and Youth Violence Prevention 26 percent of children will witness or experience a traumatic event before they turn four. During this time, the brain is developing at a rapid pace and is vulnerable to life events that may cause change to brain physiology and chemistry. If a child is subjected to multiple occurrences of trauma, especially abuse, he or she may be diagnosed with a stress disorder such as reactive attachment disorder or post-traumatic stress disorder (DSM-V). These psychopathologies have intense behavioral symptoms, which you can read more about at https://www.nimh.nih.gov/health/topics/post-traumatic-stress-disorder-ptsd/index.shtml#part_145373. However, these children do not just exhibit changes in behavior. Trauma and abuse during childhood causes chronic stress in children, which may have deleterious effects on the maturation of various brain circuitry. The brain is equipped to handle stress via particular feedback systems, such as the hypothalamic pituitary adrenal (HPA) axis. However, when children continually experience high levels of stress, their brains may alter based on exposure to certain hormones. The alteration of neurochemistry may also cause changes to specific brain structures such as the limbic system and the frontal lobe.
The HPA axis controls the body’s reaction to stress via the release of hormones, culminating in the eventual release of cortisol by the adrenal cortex. Trauma in anyone’s life often causes feelings of stress, especially in children who may not be equipped to handle these painful life experiences. If a person is subjected to chronic stress due to consistent stressors, the HPA system becomes over-active and baseline levels of cortisol rise, regardless of circumstance. The HPA axis thus becomes extra sensitive to stress and therefore may become more active, more often. Exposure to these high glucocorticoid levels can cause neuronal degeneration in the prefrontal cortex proving detrimental to executive judgment and overall cognitive functioning.
Corticotrophin-releasing-factor (CRF) is a hormone released by the paraventricular nucleus of the hypothalamus in response to stress as part of the HPA system. The amygdala, part of the limbic system in the brain, contains large amounts of CRF receptors that are involved in mediating fear and anxiety. When a surplus of CRF is present due to chronic stress, these receptors are up regulated causing heightened anxiety in the individual (Stephens, 2012). When a child has experienced abuse he or she may be easily frightened which is supplemented by intense feelings of anxiety due to high levels of this hormone.
The HPA axis continues to develop through childhood and therefore when children experience high levels of stress, specifically due to early-life trauma, the development of a properly functioning HPA axis is compromised. Children who are maltreated have high levels of cortisol, resulting in the chronic occupation of glucocorticoid receptors, which has been shown to lead to immune suppression and decreases in synaptic plasticity. Although these alterations are detrimental to individuals in the long-term, they prove to be an adaptation for children who experience abuse because it causes a state of heightened vigilance. However, this is detrimental as the child matures, often leading to higher stress vulnerability and risk of developing mood or anxiety disorders (Tarullo & Gunnar, 2006).
In addition to changes to the HPA axis, white matter volume may also be affected by abuse, especially abuse that occurs during childhood. Children diagnosed with maltreatment-related PTSD were found to have smaller cerebral volumes compared to healthy controls with deficits specifically in the dorsolateral and ventromedial prefrontal cortex (Hart & Rubia, 2012). The prefrontal cortex plays a major role in executive functioning and regulation and does not fully develop until early adulthood. This makes this brain region particularly vulnerable to developmental interruptions in children who are abused. The lack of grey matter may lead to mood dysregulation, attention deficits, and other problematic behaviors. They may also display a lack of inhibition, act impulsively in inappropriate situations, and show low levels of motivation.
Similar findings on abnormal prefrontal cortex maturation have been replicated in studies on women who were sexually abused as children and young adults who were subjected to corporal punishment during childhood. There are many forms of trauma that a child may experience, but abuse, both physical and psychological, has been shown to severely detriment the maturation and healthy development of the brain.
This past January I interned with a clinical pediatric neuropsychologist where I saw countless children diagnosed with stress-related disorders who often had comorbid diagnoses such as attention deficit hyperactive disorder (ADHD), reactive attachment disorders, and autism spectrum disorder (ASD). Many of the children I observed had been exposed to extensive trauma and/or abuse in early childhood and were already displaying intense behavioral issues.
One of the clinics I observed was a program designed specifically for the rapid psychological and medical evaluation of children who had recently been placed into the foster care system. Most of these children had seen or experienced abuse that led to their removal from their homes by child protective services. These children, some as young as six years old, had already shown severe developmental delays that were seriously impacting their cognitive and emotional abilities. Although these cases were often heart breaking, I found myself inspired by the psychologists and pediatricians who evaluated and provided treatment for these children who had gone through so many hardships. Which brings me back to the seemingly tangential reason I was inspired to write this blog post after a class discussion about Santiago Ramon y Cajal and his relationship with his father I take a firm stance in the assertion that Cajal was not great because of his father, but rather, that he was great in spite of his father.
Hart, H., & Rubia, K. (2012). Neuroimaging of child abuse: A critical review. Frontiers in Human Neuroscience, 6 (52), 1-24.
Perry, B.D. (2000). Traumatized children: How childhood trauma influences brain development. The Journal of the California Alliance for the Mentally Ill 11 (1), 48-51.
Stephens, M.C. (2012). Stress and the HPA axis: Role of glucocorticoids in alcohol dependence. Alcohol Research: Current Reviews, 34 (4), 468-483.
Tarullo, A.R., & Gunnar, M.R. (2006). Child maltreatment and the developing HPA axis. Hormones and Behavior, 50, 632-639.