How adversity shapes the developing brain and its connection to future mental health risks

While researchers have long spotlighted the role childhood abuse, poverty, and substance use play in human development researchers are pulling back the curtain on what actually happens inside the brains of the young adults affected.

For the past 10 years a research team has tracked the brain function of teens. They found adolescents who experienced early life adversity showed unusual brain activity during tasks that require focus and self-control. This finding suggests delayed development in certain areas of the brain, which is linked to higher risks for mental health disorders in early adulthood and future substance use.

What the researchers say: “Our findings show that early adverse experiences not only predict and impact mental health such as depression and anxiety, but also affect brain development,” the lead author said.

The first-of-its-kind study recently resulted in two published journal articles, one in Development and Psychopathology and another in Biological Psychiatry: Cognitive Neuroscience and Neuroimaging. The former discusses findings related to maltreatment, brain development related to cognitive control, and psychopathology. The latter focuses on connectivity between neural circuits of the brain as a predictor of substance use initiation.

The author said that despite the well documented connection between adverse experiences and the development of mental health disorders, the lack of available information on exactly how adolescents are impacted internally motivated the research.

“By age 18, more than half of adults in the United States have experienced at least one type of adversity,” the lead author added. “Yet our understanding about how adverse experiences may alter the ways in which the brain and nervous system change over time, increasing vulnerability to mental health and substance use disorders, remains vastly insufficient.”   

She and her collaborators set out to investigate this by recruiting adolescents from rural, suburban, and urban communities in Southwest Virginia, North Carolina, Tennessee, and West Virginia in 2014. Over 10 years, they tracked participant brain function, neural precursors – neurobiological markers in the developing brain – and other developmental check points through annual MRI scanning, questionnaires, and neurocognitive testing.

Participants’ family dynamics, decision-making skills, substance use initiation and frequency, personality factors, and social relationships were also assessed yearly with the goal of providing a well-rounded view of the factors impacting adolescents.

The researchers also annually observed adolescents with no prior history of substance use in the same study sample from ages 14 to 21 over a period of seven years. Their findings suggest brain connectivity (the pattern of connections between different parts of the brain) rather than cognitive control behavior (the ability to adapt your behavior to meet your goals, and to override automatic responses) was the stronger predictor of future substance use.

Specifically, stronger connectivity between the dorsal anterior cingulate cortex and the dorsolateral prefrontal cortex — two brain regions that are crucial to cognitive control — was associated with delayed substance use onset, and this connectivity pattern showed a significant drop one year prior to substance use initiation.

Some of the group’s findings also illustrate the brain’s resiliency. Although cognitive control brain functioning is delayed in early adolescence following childhood maltreatment, the findings suggest it often “catches up” during middle to late adolescence, suggesting neural plasticity and opportunities to help these young people. 

“By conducting more research on neural plasticity during adolescence, we can shed light on the brain’s potential as a target for preventive interventions, aimed at promoting resilient functioning in young people facing adversity,” the researchers explained.

By expanding this research into early adulthood, the researchers can contribute to the development of effective resilience and protective strategies to help people at higher risk of developing mental health and addiction problems improve their future wellbeing. 

The team believes they are just beginning to better understand the factors affecting young people’s mental health, substance use, and wellbeing by examining how brain function and development interact with social and emotional dynamics, and spirituality.

“Adverse experiences, no matter how we view them, are tough, but there are things we can do to help these young people develop healthier, such as access to parental support, education, and positive experiences with peer groups,” the lead author said.

My take: One of the things omitted from this research—probably because it was not part of the original brief—is the genetic and other biological basis of resilience. An individual’s ability to “bounce back” from adversity is a combination of three factors: our childhood experience, our DNA/mRNA (including molecular structure of certain genes and particles of RNA) and our context.

Depending on the study you read, between 10 and 25% of us have the genes associated with a higher level of resilience. There are, according to the most recent studies, three very interesting genes that have an effect on resilience: ROBO1, CIB3 and LYPD4. Your level of resilience may depend on the way that these genes function (or are expressed) within your brain.

Fascinatingly, these three genes have functions in establishing and maintaining connections between neurons in the auditory system. It would seem that the stronger these connections the greater your resilience. Several researchers have recently speculated that music appreciation is closely associated with resilience and that music therapy might be a way of altering the expression of these genes and thus increasing resilience.

These same studies explore in more detail other possible links between gene expression and environmental/experiential factors.

This present study concentrates on the aspect of experience, especially adverse childhood experience. The assumption that the researchers have is that changing the context that the non-resilient person is in can increase their resilience. That might well be so. There is some research indicating that placing someone in a situation where they have additional social and emotional support can increase their resilience (presumably through influencing the expression of oxytocin and dopamine genes).

Other research has shown that emotions, such as those connected with resilience (e.g. optimism) can be contagious. Being with resilient individuals can therefore add to a person’s resilience, again by altering the expression of individual genes.

A great deal of research is needed to develop practical therapies to increase resilience, largely because each of us has had a different and complex set of experiences. What genes are associated with lack of resilience due to experiences such as poverty, or racial discrimination? Would PTSD—largely based on genetic predisposition—be amenable to better outcomes if we knew which contextual interventions altered the expression of the appropriate genes? At the moment we have no real evidence of the gene/context/for any of these.

At the moment we are still fumbling in the dark.