Previous research indicates that prenatal cannabis exposure is linked to mental health conditions in childhood and adolescence. Until now, however, the potential underlying biological mechanisms have remained unclear.
In the current study, researchers examined healthcare data from the Adolescent Brain and Cognitive Development (ABCD) Study to identify brain changes following prenatal cannabis exposure. Data included information about mothers' substance use prior to giving birth and neuroimaging data at ages 9-12.
Altogether, 370 children were exposed to cannabis prior to mothers learning of their pregnancy, and 195 were exposed to cannabis before and after learning of pregnancy. The researchers examined a variety of neuroimaging data, including measures of brain thickness, surface area, and measures of water diffusion in and out of cells.
Ultimately, they found that prenatal cannabis exposure was linked to localized differences in great and white matter of the frontal and parietal cortices, their associated white matter tracts, and striatal rest-state connectivity.
Lead author Ryan Bogdan, the Dean’s Distinguished Professor of Psychological & Brain Sciences at Washington University in St. Louis, said in a press release that the observations may stem from the anti-inflammatory effect of cannabis. While reducing inflammation can have a positive impact in some cases, excessive reduction of inflammation at the wrong time could affect the pruning and priming of the developing brain.
A major limitation of the findings is that the dataset was retrospective, with mothers reporting cannabis use 10 years prior. The researchers are thus looking forward to data from prospective, longitudinal studies that will include more recent, accurate, and detailed information about cannabis use during pregnancy.
Sources: EurekAlert, Nature Mental Health