The neurobiology of childhood trauma, from early physical pain onwards: as relevant as ever in today's fractured world

Abstract

Background: The situation in the world today, encompassing multiple armed conflicts, notably in Ukraine, the Coronavirus pandemic and the effects of climate change, increases the likelihood of childhood exposure to physical injury and pain. Other effects of these worldwide hardships include poverty, malnutrition and starvation, also bringing with them other forms of trauma, including emotional harm, neglect and deliberate maltreatment. Objective: To review the neurobiology of the systems in the developing brain that are most affected by physical and emotional trauma and neglect. Method: The review begins with those that mature first, such as the somatosensory system, progressing to structures that have a more protracted development, including those involved in cognition and emotional regulation. Explored next are developing stress response systems, especially the hypothalamic-pituitary-adrenal axis and its central regulator, corticotropin-releasing hormone. Also examined are reward and anti-reward systems and genetic versus environmental influences. The behavioural consequences of interpersonal childhood trauma, focusing on self-harm and suicide, are also surveyed briefly. Finally, pointers to effective treatment are proffered. Results: The low-threshold nature of circuitry in the developing brain and lack of inhibitory connections therein result in heightened excitability, making the consequences of both physical and emotional trauma more intense. Sensitive and critical periods in the development of structures such as the amygdala render the nervous system more vulnerable to insults occurring at those points, increasing the likelihood of psychiatric disorders, culminating in self-harm and even suicide. Conclusion: In view of the greater excitability of the developing nervous system, and its vulnerability to physical and psychological injuries, the review ends with an exhortation to consider the long-term consequences of childhood trauma, often underestimated or missed altogether when faced with adults suffering mental health problems.

Keywords: Development; childhood; neglect; neurobiology; pain; trauma.

Figure 1.

Childhood trauma and its effects on biobehavioural systems implicated in pain and psychiatric disorders During development, distinct neurological systems mature at different rates, accompanied by changes in neurobiological mechanisms at the molecular or cellular level. Throughout the neurodevelopmental trajectory, and as a result of ongoing CNS maturation processes, children are arguably more vulnerable to the unfortunate and negative impact of childhood trauma, maltreatment in particular. In the developing CNS, maltreatment is hypothesised to interfere especially with systems that regulate threat detection, fear processing, reward and anti-reward mechanisms, and other fundamental neurological properties (e.g. white matter integrity). Over time, the impediment of normal neurodevelopmental process stemming from childhood trauma might commonly facilitate abnormal pain and somatosensory processing, psychiatric symptoms and illnesses, and complex comorbid states. (Adapted from Cay et al., ; Govindan et al., with kind permission of the authors).