Even casually smoking marijuana can cause abnormalities in
the developing brain, according to the results of a new study funded by
the National Institutes of Health.
High-resolution MRI scans of the brains of adults between
the ages of 18-25 who reported smoking weed at least once a week were
structurally different than a control group: They showed greater grey
matter density in the left amygdala, an area of the brain associated
with addiction and showed alterations in the hypothalamus and
subcallosal cortex. The study also notes that marijuana use “may be
associated with a disruption of neural organization.” The more weed a
person reported smoking, the more altered their brain appeared,
according to the Northwestern University and Harvard Medical School
study, which was published in the
Journal of Neuroscience.
The finding already has the study’s authors calling for states to
reconsider legalizing the drug. Hans
Breiter, the lead author, said he’s “developed a severe worry about
whether we should be allowing anybody under age 30 to use pot unless
they have a terminal illness and need it for pain.”
Previous marijuana studies have shown
brain abnormalities in chronic users and in teens,
but the researchers say this is the first time that there are
structural differences between recreational users and those who don’t
smoke weed. The study says that the parts of the brain altered have been
associated with schizophrenia, Parkinson’s disease,
obsessive-compulsive disorders, and Tourette’s syndrome.
The study suggests that “pending
confirmation in other cohorts of marijuana users, the present findings
suggest that further study of marijuana effects are needed to help
inform discussion about the legalization of marijuana.”
The veracity of the study’s findings comes down to how you
define “recreational.” Though none of the users were “addicted” to weed
(the researchers’ words, not mine, so take up your “weed is not
addictive" battle with them), most of them smoked pot fairly regularly.
On average, those studied smoked weed about 4 days a week, smoked 11
joints a week, had regularly smoked weed for about six years, and had
started when they were about 16.
It's the first study that has found these brain
abnormalities in casual users (previous mice studies have had similar
results), but it's just another study in the proverbial garden of them.
It further muddles what legalization is getting at: Is weed good or bad
(or, beyond that—should adults be able to decide if they want to do it
anyway)?
The fact that Colorado is raking in far more tax money
from legal weed than it originally expected (good!) and hasn’t seen any
disastrous things happen (good!) has certainly piqued the interest of
other states looking to cash in on the crop. Now there's this study
(bad!). Whether it has any impact on legalization efforts around the
country remains to be seen, but it certainly doesn’t help the cause.
