Casual Marijuana Use Harmful to Brain Development: Harvard

From what I can see, no other scientific question brings out the banshees so much as a study that finds that use of marijuana/cannabis is detrimental.  So too has been the reaction to Harvard Medical School research, published in the Journal of Neuroscience, that details permanent damage to the brain as a result of even casual use.  The study is hardly unique in its findings, such as this one, for example.

The study used 3-D imaging of subjects' brains to determine physical alterations and found a significant statistical correlation.  The test consisted of 40 college students divided into two groups of those who have used cannabis in varying degrees and who have not used it at all.  "The scientists found that the more cannabis the 40 subjects had used, the greater the abnormalities."

The author of the study was Dr Hans Breiter, professor of psychiatry and behavioral sciences at Northwestern University Feinburg School of Medicine:

This study raises a strong challenge to the idea that casual marijuana use isn't associated with bad consequences.  Some people only used marijuana to get high once or twice a week.  People think a little recreational use shouldn't cause a problem…. Our data directly says this is not the case.

Areas within the brain that were examined involved emotion, motivation and addiction.  Anne Blood, assistant professor of psychiatry at Harvard Medical School:

These are core, fundamental structures of the brain.  They form the basis for how you assess positive and negative features about things in the environment and make decisions about them.

Jodi Gilman of the Massachusetts General Center for Addiction Medicine:

It may be that we're seeing a type of drug learning in the brain.  We think when people are in the process of becoming addicted, their brains form these new connections.

One detractor criticizes the size of the sample, "not big enough to draw conclusions".  Standing alone, that is a true if not necessarily accurate statement.  But a solid conclusion can be drawn if the differences between the two groups are significant, as this study alleges.

The appropriately named Professor Nutt goes on to say, "Whatever cannabis does to the brain its not in the same league as alcohol which is a proven neurotoxin." [sic]

Yet the study is not about alcohol, is it?  However often this tired distraction is dragged out, the fact that alcohol can be a toxic agent does not alter the fact that cannabis is pernicious.  Acute alcohol usage over time does destroy brain cells; use of marijuana in the young alters the brain structure in a malign way.

On the political side of the argument, that marijuana usage is a matter of free will and liberty, I have to argue – conservative that I am – that society has an obligation to protect itself from the more nihilistic aspects of human nature.  Liberty does not equate with license.  I have met more than a few purported Libertarians who are particularly focused on the issue of pot legalisation, but fade away on any other subject.  I question the quality of the woolen coverings of their canine appetite.

And as I began this piece, sometimes the quality of the argument is measured by the numbers of its stentorian enemies.  Let us not forget that a typical side effect of marijuana usage is pronounced paranoia.

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As if by coincidence, today marks the anniversary (1943) of the discovery that LSD is an hallucinogenic drug.  Much like cocaine, it was initially proclaimed to be benign until overwhelming evidence finally prevailed upon the pop culture that it was anything but.

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Update: The Economist also examines the Harvard study.