Childhood trauma refers to an event experienced by a child that threatens their life or bodily integrity. These events are emotionally painful or distressful and can result in long-lasting physical and mental effects. The three main types of trauma include: acute trauma (resulting from a single incident), chronic trauma (repeated or prolonged trauma) and complex trauma (where there are multiple and varied traumatic events).
Previous studies have shown that 15-43% of children go through at least one form of childhood trauma. From those individuals, 3-15% of girls and 1-6% of boys develop post-traumatic stress disorder (PTSD). However, this is likely to be an underestimation due to the lack of reporting by children and the low level of mental health diagnoses. The most frequent form of childhood trauma is neglect (65%), followed by physical abuse (18%), sexual abuse (10%) and lastly, psychological abuse (7%) (National Centre for PTSD, US).
A meta-analysis study published by the American Psychological Association investigated the relationship between experiencing childhood trauma and biological ageing. It is already clear from previous studies that childhood trauma can predict future life patterns in psychological and physical health. However, it has been unclear whether it is linked to the speed of ageing.
For this study, the researchers focused on two forms of childhood trauma: threat-related (abuse or violence) and deprivation-related trauma (emotional or physical neglect or poverty). As well as three indicators of ageing: the age at which puberty began, cellular ageing and changes in brain structure. The meta-analysis included 80 studies with up to 116,000 participants.
The results found by the researchers demonstrated that:
- Children who had suffered threat-related trauma (abuse or violence) entered puberty earlier. They also had shortened telomeres demonstrating accelerated cellular ageing. Telomeres are ‘protective caps’ at the end of DNA molecules that make up chromosomes. The shortening of telomeres may lead to cell death, tumour development or senescence (gradual deterioration of functional characteristics), overall affecting the health of an individual. Individuals with shorter telomeres have been associated with increased incidence to diseases and poor survival.
- Whilst the children who suffered deprivation-trauma (neglect or poverty) did not age earlier.
A further analysis looking at brain development was carried out using 25 studies with 3,253 participants. The results showed that early-life trauma does affect brain development. Childhood trauma is associated with reduced cortical thickness (a sign of ageing as cortical thickness reduces with age). However, the parts of the brain that would thin was dependent on the form of childhood trauma experienced:
- Threat-related trauma (abuse or violence) is associated with thinning specifically in the ventromedial prefrontal cortex (vPFC). The vPFC is involved in emotional and social processing.
- Deprivation-related trauma (neglect or poverty) was associated with thinning in the frontoparietal region, default mode and visual networks involved in cognitive and sensory processing.
It is likely that these biological and physical responses were once adaptive (beneficial for the survival of the individual). For example, early puberty allows individuals to reproduce earlier and before death, which may be essential in a threat-filled and violent environment. However, accelerated pubertal timing today has been linked with a number of mental health problems, such as: heightened levels of risk-taking behaviour, substance abuse and delinquency.
Overall, this accelerated and altered development is likely to trigger health and mental health consequences once adulthood is reached. However, additional studies will be needed to assess how these children are actually affected by the altered development throughout their lives. The authors of the study are intending to look further into whether these long-term consequences can be prevented or slowed down earlier in life.
Original source: N. L. Colich, M. L. Rosen, E. S. Williams and K. A. McLaughlin (August 2020). Biological ageing in childhood and adolescence following experiences of threat and deprivation: a systemic review and meta-analysis. American Psychological Association, Psychological Bulletin.