Is This About My Childhood? — Part Three

How Childhood Adversity Affects the Developing Brain and Stress Response

In the last post on this topic, I talked about the finding that early life experiences affect what happens to us as adults.

We talked about how it affects our mental health, our relationships, and our physical health. We saw examples of how adverse childhood experiences tended to make people more likely to experience things like depression, addiction, violence and abuse.

One thing that we haven’t seen yet is how exactly this tends to happen. Maybe this is just… bad luck?

Well, the good news is that research has some answers to this question. The bad news is that the answers are often unpleasant to hear.

In this post, I’ll explore a few studies that show the mechanisms by which this effect happens.

The brain gets changed by experiences

The development of the brain is a process that is both scripted and experience-dependent. Genetics will direct how the brain develops, but what happens to the child (their experiences) will sculpt the brain.

Experiences that happen during early sensitive or critical periods of brain development will have a bigger impact. This is what Teicher and colleagues discuss in their 2016 paper¹.

This does not mean that every time a child experiences something unpleasant, stressful, or painful, they will be marked for life. Not at all. In fact, stress is necessary for development and for healthy adult emotional regulation².

What can result in harmful consequences is the kind of stress that is particularly intense, prolonged, or frequent, and happens when the child doesn’t have enough support to get through it.

According to one review², the amygdala, a brain region involved in noticing things that are important (such as potential threat), detects threat and activates another brain system responsible for stress. This raises cortisol levels before other brain areas (hippocampus and PFC) help return the stress response to its normal levels.

When stress turns chronic, the amygdala can become overreactive, while the brain areas that bring it back to baseline levels become less effective.

In other words, the system responsible for stress and regulation becomes too easily activated, and takes longer to settle back.

The brain can become better at detecting threat

The more children are placed in such situations, the more easily the brain detects danger, anger, threat, or unpredictability. These situations become more “important” to the brain.

This has been shown in several studies, for example, by measuring children’s reactions to angry and neutral faces³. Physically abused children were more likely to pay attention to angry faces and found it harder to shift their attention away from them. They could even identify anger more accurately from less visual information.

With this heightened attention towards anger, children who were physically abused tended to interpret ambiguous scenarios as involving malevolent intent. For instance, when given a scenario in which another child broke their radio while they were out of the room, abused children were more likely to assume the other child did so on purpose. They were also more likely to generate an aggressive response.

Brain-imaging studies confirm the changes in the brain

Remember the earlier amygdala and stress relationship? Well, this has been shown to be connected, too.

Brain-imaging studies found that people with childhood maltreatment histories had greater amygdala response to emotional faces, especially threatening or salient ones. These differences even appeared during the initial, less-conscious, faster processing stage. In other words, they happened before the person had a chance to process what they were looking at.¹

Other studies even showed that the connections between the amygdala and the prefrontal cortex and hippocampus may be weaker, so the amygdala gets less input from brain areas that help control reactions and make sense of the situation. At the same time, its connections with systems involved in the body’s stress response help trigger a faster arousal response and physical preparation to react. In other words, it may allow the body to react more quickly once the amygdala is activated.¹

The brain is not injured; it’s adapting.

Researchers point out that these reactions are not an injury to the brain and appear to be more in line with adaptive changes based on the person’s experience.¹

There are important benefits to these changes, including:

• faster threat detection may help in a dangerous environment;
• heightened stress reactivity may help someone act quickly;
• greater sensitivity to subtle signs of anger may provide earlier warning;
• increased attention to possible danger may make threats harder to miss;
• quicker physical preparation may help someone defend themselves or get away;
• these changes may help someone avoid threats altogether.

That’s why it’s so important to remember that trauma reactions often make absolute sense in the moments when they are experienced. The fact that they no longer appear adaptive is problematic, but it is an unfortunate side effect of these experiences, not the intention.

Importantly, these studies also show that not everyone who develops maltreatment-related brain differences has a psychiatric disorder, meaning brain differences do not automatically equal psychopathology.¹

These outcomes also vary significantly from person to person, and not every person who goes through these traumatic experiences develops the same outcomes (and some appear not to develop any).³

That said, understanding these adaptations gives us a better explanation, and being able to understand ourselves is the first step toward healing.

If a response developed through experience, that also gives us something specific to work on.

But this raises another question: does it matter what kind of adversity a child experiences? An ACE score tells us how many adverse experiences someone had, but it does not tell us whether those experiences affect development in the same way. That’s what I’ll look at in the next post.

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References

1. Teicher, M. H., Samson, J. A., Anderson, C. M., & Ohashi, K. (2016). The effects of childhood maltreatment on brain structure, function and connectivity. Nature Reviews Neuroscience, 17, 652–666. https://doi.org/10.1038/nrn.2016.111
2. Shonkoff, J. P., Garner, A. S., Committee on Psychosocial Aspects of Child and Family Health, Committee on Early Childhood, Adoption, and Dependent Care, & Section on Developmental and Behavioral Pediatrics. (2012). The lifelong effects of early childhood adversity and toxic stress. Pediatrics, 129(1), e232–e246. https://doi.org/10.1542/peds.2011-2663
3. Jaffee, S. R. (2017). Child maltreatment and risk for psychopathology in childhood and adulthood. Annual Review of Clinical Psychology, 13, 525–551. https://doi.org/10.1146/annurev-clinpsy-032816-045005