By Tom Horvath, PhD
This finding is an opportunity to highlight the ABCD, the Adolescent Brain Cognitive Development study. The ABCD, launched in 2015 and funded by the federal government, is the largest US long-term study of brain development and child health. The project involves 21 research sites, 50 principal investigators, and 11,880 children who were ages 9-10 at the initiation of data gathering. Assuming continued funding, the study will last at least 10 years.
This specific subset (of this massive dataset) looked at structural brain changes in subjects who had tried any substance by age 15, vs. those who did not. Differences in several brain regions, all pre-existing substance use, were identified. These findings, interpreted collectively, suggest that in the subjects who used substances, there was reduced capacity for inhibition and self-regulation, and increased sensitivity to reward. The differences were clear but modest. There were also some modest differences by substance. Why these differences exist was not studied.
To remind you, when there are many subjects (in this specific study, 9,804) we can identify differences that would be too small to identify in a smaller number of subjects.
By comparison, if I toss a coin 10 times and get 6 heads/4 tails, I should not consider the result significant. If I toss the same coin one million times, and get 600,000/400,000, that result is statistically significant. Be careful with any bets you place on that coin!
How clinically significant is this finding? First, it ideally needs to be replicated. Then, assuming we could quickly and inexpensively get this information about a young person and discover that it is positive, what might we do differently with that person? It is too soon to say. More research is needed, and hopefully the ABCD will provide some of it.
The study: https://pmc.ncbi.nlm.nih.gov/articles/PMC11686416/
A detailed review of the study: https://www.recoveryanswers.org/research-post/does-brain-structure-predict-early-substance-use-initiation/