The True Link Between Early Trauma and Adult Mental Health

The last decade of the 1990s was often labeled the “Decade of the Brain,” as many mental health clinicians and researchers emphasized biological and genetic factors as contributing to both mental health and illness. Over the last 15 or so years however, the pendulum has swung the other way, with a lot of focus on the role of traumatic and adverse experiences as the primary contributors to mental health disorders. Included in the expanded definition of adverse experiences are societal factors, often called social determinants of health, that include things such as poverty, racism, and lack of access to safe and healthy environments.

And as occurs routinely these days, the discussion about the causes underlying mental health problems has become infused with politics, which tends to lead to a more polarized debate. While there are always exceptions, the political left is often credited or blamed for pushing this concentration on the negative impacts of trauma.

The introduction of the trauma-informed care (TIC) model has brought with it not only changes in clinical understanding and treatment but also the need to alter our language and institutional practices in an effort to be more “trauma-informed.” This effort has met with some pushback, often from right-leaning individuals who complain that the definition of trauma has been watered down from its original intentions. Many of these folks also grumble about any insistence to be more sensitive in their language as part of the larger rebellion against “wokeness.”

In science-oriented circles, a criticism against the accumulating body of research showing a link between early trauma and various outcomes (mental health disorders, brain changes, etc.) is that these studies often are not equipped to tease out direct causal effects of the trauma itself from other potentially important causal factors.

Let’s say, for example, that you want to study adolescent aggressive behavior and the effect childhood physical abuse might have on it. Many studies doing just that have essentially only measured those two things and then suggested in their conclusions, upon finding a significant association, that the physical abuse is causing the adolescent aggression.

This is certainly possible, but the problem with such an interpretation is that it is also possible that something like shared genes are also contributing to the presence of both an aggressive parent and an aggressive adolescent. Without measuring this alternate hypothesis directly, it can mistakenly appear that it’s the abuse itself that is the culprit. (For the record, most studies like this acknowledge this limitation, which often gets ignored in the headlines, blogs, and raging online arguments).

All this brings us to a very interesting study recently published in the American Journal of Psychiatry that summarizes studies analyzing the link between different types of child abuse and later mental health problems. But rather than review and analyze all studies on this topic, the authors confined themselves only to those investigations that used what they called a “quasi-experimental” design.

This means that the study did something special to be able to measure and control for another factor or factors that might be driving any link they found between maltreatment and later psychiatric disorders. These designs, for example, might include using twins or adoptees in your study to help tease out underlying genetic effects, or using some newer and fairly sophisticated statistical analyses that can account for the presence of confounding factors that make it appear that your variable of interest is causing there to be an association when it actually isn’t.

The authors were able to find 34 studies, which they statistically combined in a process called a meta-analysis to compare how strong the association was between child maltreatment and future mental health problem under two conditions: 1) when other factors were not taken into account, and 2) when they were.

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What they found under the first condition was that child maltreatment showed a statistically significant association with many different psychiatric disorders with an overall effect size that could be described as moderate. However, when those other factors that these studies measured were taken into account, the strength of the association fell 45 percent into what would be considered a small effect, albeit one that remained statistically significant.

Looking more closely, the authors further found that gender didn’t seem to matter much in their results, or which particular diagnosis was assessed. The type of study also didn’t seem to make a whole lot of difference either. One thing that did have some effect, surprisingly, was the type of maltreatment, and here it was found that the link between maltreatment and later mental health problems seemed to be a little stronger for emotional abuse and institutional neglect (like being raised in a huge orphanage with few resources) compared to other types of abuse or neglect.

The authors concluded that there does indeed appear to be a direct link between child maltreatment and later psychiatric disorders, but that the magnitude of this link may be much less than we have been led to believe because most studies don’t do a good job of accounting for other potential causes of mental health disorders.

Politically, this study undercuts some arguments at either extreme of this debate. For those declaring that mental health problems are all about trauma, this rigorous review strongly suggests that other factors likely play a role and are often missed by studies that choose not to account for them.

At the same time, not only does the association of trauma to later psychiatric disorders remain even after accounting for these other causes, it looks like things such as emotional abuse (which some have argued shouldn't necessarily count as "trauma") are responsible for much of the link with the development of mental health conditions. Further, the authors also suggest that other social determinants of health may play additional roles here.

While getting a better understanding of the causes of mental health problems is obviously crucial for prevention efforts, it’s also important to remember that cause and treatment don’t always need to match. For example, the impact of some genetic conditions are readily neutralized by just getting some specific nutrients in the diet. Conversely, certain diseases clearly caused by environmental events (like getting a cut that becomes infected) need to be addressed with “biological” treatments such as medications.

Time and time again, good research shows us that politically motivated extreme views, while good at inciting emotion and gaining social media followers, often fall quite short of the mark when it comes to explaining what is actually going on. Yes, having to think about trauma and genetics and social determinants of health and many other factors when it comes to how mental health conditions develop is messy and hard to fit into a soundbite, but as the popular quote goes, “for every complex problem, there is an answer that is clear, simple, and wrong.”

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