Childhood developmental experiences shape our adult selves, and in particular affect cognitive and brain development. Uncovering the multiple pathways involved in the relationship between past events and current difficulties with regard to poor mental health can expand our understanding of childhood trauma and the therapeutic responses needed by those seeking help.
Studies show that chronic stress negatively impacts cognitive function, especially, during the early stages of life. However, the mechanism behind this remains unclear. One possible explanation is ‘allostatic load’, which roughly translates to the wear and tear on the body and brain. Many scholars have linked early life adversity with higher allostatic load during adulthood, as well as weaker cognitive abilities, suggesting it may mediate the association between early life adversity and later life cognitive functions. Researchers at DPUK were curious to know more.
“I was personally interested in this topic after discovering some shocking outcomes of childhood adversity,” said Dr Sarah Bauermeister, Senior Scientist at DPUK and senior author of the paper. “It acted as a catalyst for me to do something about the deleterious consequences of early maltreatment on later stages of life.”
Using the DPUK Data Portal, the research team set out to provide more clarity on this association. The researchers, including first author Morgane Künzi at the University of Geneva, found that adversity experienced in early life is associated with poorer cognitive health in middle and later life. Higher cumulative life course adversity was also seen to be correlated with a higher level of depression. Data from more than 500,000 participants aged 37 to 73 was collected from a large population-based prospective cohort study, UK Biobank. Childhood adversity was measured in terms of exposure to a variety of experiences including physical, sexual and emotional abuse using the Childhood Trauma Questionnaire. Five different variables were considered alongside the measure of cognitive function: cumulative life course adversity, depression, age, gender, and education. These types of comparison have never been done at a large scale before.
What was noteworthy was the type of adversity most strongly associated with cognition. Dr Bauermeister said: “When we started this work, we reasoned that exposure to general adversity would matter most to cognitive performance. Although this was true, it was exposure specifically to abuse and neglect that turned out to be the strongest predictors.” She added that the results are in accordance with literature showing an association between cumulative adversity and depression. The results support the hypothesis of a direct association between experiences of maltreatment over the life course and cognition. However, it is depressive symptoms that partially account for this association.
What does this study mean for researchers working towards understanding mental health difficulties and dementia? First, that the effects of trauma on the brain are more broadly experienced than we first imagined. Second, that the widely held view that life experiences result in changes to cognitive function is only part of the picture. Instead, we need to place more focus on understanding how early childhood adversity may result in different kinds of mental health disorders, such as depression. The final point is that of hope: evidence from the study demonstrates the need for reinforcing the understanding that dementia prevention may need to begin in childhood. They also indicate the need for early adversity interventions, and call to prioritise good mental health across the lifespan.