Correlating Thick Brains with Thin Bodies
Correlations can be fun. For example, from Tyler Vigen, we can learn that the divorce rate in Maine correlates beautifully with per capita margarine consumption. In a more serious analysis this week, we learned that thick brains in children might correlate with thin bodies. But what does this mean? If you read closely, the answer is not too much. Not by itself.
This research comes from an important study of brain development in children and adolescents. But as the authors themselves note, this study doesn’t support any firm conclusions. Instead, it offers interesting questions to fuel further research.
The ABCD Study
These data come from the Adolescent Brain Cognitive Development study. It’s a big, important project that aims to examine the relationships among brain development, childhood experiences, and many dimensions of health. NIH rightly calls it a landmark study.
Researchers examined the thickness of different parts of the brain. They used data from 3,190 children. Those data were cross-sectional – a snapshot in time. Thus, they cannot prove anything about cause and effect. Even if these relationships are causal, we can’t know which is cause and which is effect. They might be mutually reinforcing. Or the relationship might be due to any of a huge array of possible, yet unmeasured, confounding factors.
Nonetheless, they found an association of BMI with development of the brain’s prefrontal cortex. This observation lined up with diminished executive functions, such as working memory.
Extreme Caution Needed
In a companion editorial, Charles Wood, Bernard Fuemmeler, and Eliana Perrin urge caution. This study can generate very important hypotheses. The ABCD project will yield tremendous amounts of information over time. But that will beg more questions. If we leap to unsupported conclusions, we will continue to delude ourselves about obesity, its causes, and its effects.
And misperceptions about obesity bring bias toward the people who have it. Wood et al explain:
We must also be careful about how findings such as these, if misinterpreted, could perpetuate explicit and implicit bias toward children and adults with obesity by implying that obesity is the result of poor individual control or that obesity causes poor brain function.
Thus, we need objectivity about what this research does and does not tell us. We need curiosity to follow up and seek a deeper understanding of its meaning. And above all, we need to use this knowledge to provide better care for the people affected.
Click here for the study and here for the editorial.
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December 12, 2019
