Remember the neuroscience study this spring that seemed to indicate that even casual marijuana use could cause lasting changes in teen brains? It was, shall we say, a bit controversial — to the point that the Knight Science Journalism Tracker, a leading arbiter of science coverage, questioned both what the study's authors said and how the media handled it, here: Don't bogart that joint: Casual marijuana use linked to brain changes?
Now, a new study on rats out of the University of Massachusetts at Amherst and Louisiana State suggests that binge drinking in adolescence can cause long-lasting damage to brain pathways still developing in the young. The press release quotes neuroscience researcher Heather Richardson of UMass:
"Adverse effects of this physical damage can persist long after adolescent drinking ends. We found that the effects of alcohol are enduring." She adds, "The brains of adolescent rats appear to be sensitive to episodic alcohol exposure. These early experiences with alcohol can physically alter brain structure, which may ultimately lead to impairments in brain function in adulthood."
She and her colleagues believe their study is the first to show that voluntary alcohol drinking has these effects on the physical development of neural pathways in the prefrontal cortex, one of the last brain regions to mature.
In humans, early onset of alcohol use in young teenagers has been linked to memory problems, impulsivity and an increased risk of alcoholism in adulthood. Because adolescence is a period when the prefrontal cortex matures, Richardson adds, it is possible that alcohol exposure might alter the course of brain development. Rodent models used in this study are documented to have clinical relevance to alcohol use disorder in humans.
Of particular concern: I think of the prefrontal cortex as, well, where I think, the seat of rationality and control, the highest of the higher brain functions. Not a good place to damage — not that there's any good place in the brain to damage.
On the lasting effects:
In a final experiment, the researchers found that heavy adolescent alcohol drinking, but not sweetened water, predicted poor performance on a working memory task in adulthood. This supports the idea that the enduring effects of alcohol may not only be structural but could also affect cognitive functions that are dependent on a healthy prefrontal cortex.
Overall, they conclude, "These findings establish a causal role of voluntary alcohol on myelin and give insight into specific prefrontal axons that are both sensitive to alcohol and could contribute to behavioral and cognitive impairments associated with early onset drinking and alcoholism."
Readers, how do you see these new findings playing out in the ongoing debate over legalizing marijuana? Do they add legitimacy to that previous pot study? Do they underscore that alcohol does more harm than marijuana? Or...?