“It is possible that the abnormal brain structures reveal a pre-existing vulnerability to marijuana abuse,” Smith said. “But evidence that the longer the partic

“It is possible that the abnormal brain structures reveal a pre-existing vulnerability to marijuana abuse,” Smith said. “But evidence that the longer the participants were abusing marijuana, the greater the differences in hippocampus shape suggests marijuana may be the cause.” Correlation, sure, but correlation with length of usage. Definitely a more interesting angle than simply usage <-> deformation.