Table of Contents

Volume 4, Issue 2                                                                                      February, 2018

Current Study

Childhood psychopathology alters the brain, not vice versa

 Brain MRI abnormalities are effects, not causes

Here is the typical story.  A researcher shows a colorful picture of the brain, with a certain part being too small or too large, or having too little or too much blood flow. Then the researcher claims that these brain imaging changes support the validity of a certain diagnosis.  In children, the common claim is that brain imaging changes support the validity of the diagnosis of ADD.  

The problem, as all know, is that correlation cannot be assumed to be causation. The brain is always changing.  How do we know we are dealing with an illness?  There are differences in the brain PET scans of Republicans and Democrats.  Are those diseases? 

Further, which way does the arrow of causality go?  Are the brain changes causing the illness? This is what is assumed usually. But there is another possibility: It could be that the illness is causing the brain changes. 

This study is able to answer this question in relation to the construct of childhood ADD because it is prospective: it examines clinical diagnosis and brain imaging at different times moving forward in childhood.  Its conclusion:  brain changes are effects, not causes.  They do not prove validity of ADD.

In this study 845 children received brain MRI testing at ages 8 and 10. They also had clinical assessments at ages 6, 8, and 10.  The researchers divided clinical symptoms into two basic categories of “externalizing” (agitation, excitation, impulsivity) and “internalizing” (sadness, anxiety, withdrawal) symptoms.  

Higher externalizing symptoms at age 6 were associated with later smaller total brain volume, with reductions in both gray and white matter, and smaller subcortical brain volume.  Over four years, the association of externalizing symptoms remained strongest for smaller subcortical brain volume.  

Higher internalizing symptoms at age 6 had no associations with brain changes initially, but after four years, there was some association again with smaller subcortical brain volume. 

Neuroimaging at age 8 did not predict changes in externalizing or internalizing symptoms at age 10.  

So, the prospective design allows for some claims of causality.  If one event happens before a change in another event, the first event is more likely to be a cause.  If one event does not precede another event, then the first event is not likely to be a cause.  Here, MRI brain findings did not correlate with any later changes in psychiatric symptoms. In other words, MRI findings did not “cause” anything. In contrast, psychopathological states were associated with later changes in brain MRI.  Or, psychopathology seemed to cause brain MRI changes.  Specifically, externalizing symptoms of impulsivity and excitation caused atrophy of subcortical brain structures.  

What are we to conclude?  Rather, this study tells us what not to conclude:  Brain MRI abnormalities occurring along with psychiatric symptoms does not mean that the former cause the latter; it could be the other way around. 

Lastly, how can symptoms change the brain? We know that psychomotor excitation (e.g., mania, stress reactions, psychosis) is associated with overactivity of the hypothalamic-pituitary axis (HPA), with overproduction of steroid hormones, which are excitotoxic in the brain, causing cortical atrophy. This link is rather well established.  It could be a mechanistic explanation for the clinical/biological finding of this study: clinical psychopathology leads to brain abnormality, not vice versa.

Clinical implications

These results could support the view that controlling psychopathological symptoms is beneficial for the brain, and that short-term symptom improvement could have long-term neurological benefits.  

The PL Bottom Line

  • MRI brain abnormalities may be the effect, not the cause, of psychopathological clinical symptoms in childhood.  

PL Reflection

The phenomenon of uncompromising belief stands against science.  The great majority of people subscribe to “belief” not as “perceiving the truth of something” but as “taking this as the basis for life.”  The second belief is much firmer and more fixed than the first one…It can sometimes be upheld to a point where it seems completely absurd, and…then it only ends with the death of the believer….

But there must always be a fundamental complementarity between deliberation and decision. In the practical decisions of life it will scarcely ever be possible to go through all the arguments in favor of or against one possible decision, and one will therefore have to act on insufficient evidence.  The decision finally takes place…by cutting off all further pondering.  Even the most important decisions in life must always contain this inevitable element of irrationality.  The decision itself is necessary since there must be something to rely upon, some principle to guide our actions….

[We need] a new kind of balance between thought and deed, between activity and meditation.  

Werner Heisenberg

Physics and Philosophy

Meet our expert EDITORIAL BOARD, composed of clinicians and researchers from around the world. 

Subscribe to the RSS feed below to follow our "What's new" blog posts