pediatric housecalls Robert R. Jarrett M.D. M.B.A. FAAP

Prenatal Marijuana (Cannabis) and Brains

To my way of thinking the very thought that medical researchers are forced to stop what they are doing on important issues beyond our control and do research to prove that marijuana is bad for you and shouldn’t be used as a “toy” is unconscionable to the extreme.

We just can’t let the scammers and dealers destroy unborn babies like they did pushing tobacco however; so, that’s just what researchers had to do.
Do you really need to ask? YES, smoking marijuana is damaging to a pregnant women’s baby!
Absolutely anyone who can read is able to find that many other studies have already been done which prove that drug users who smoked marijuana (cannabis) during pregnancy inflict poorer behavioral outcomes of many types on their offspring.

Shouldn’t that be all that’s necessary for a caring society to keep the use of marijuana under tight control, only for use in specific cases of medical necessity where the rights and well-being of unborn children have fully been taken under consideration—by someone other than the person who is going to get “high?”

Harm of Using Marijuana During Pregnancy
The Smoking Gun—It Alters Children’s Brains

Feeling like the world needed to document the “smoking gun,” or at least better understand the mechanism, Dr. Hanan El Marroun of Erasmus University in the Netherlands and his colleagues wrote about their evidence in June’s edition of Biological Psychiatry.

Generation “R” Study – Prenatal Marijuana

Why the Netherlands? Well it turns out that it was a great place to do it because the country has a massive “Generation R Study” already well underway. It is what is known as a population-based prospective cohort study where huge numbers of individuals of a certain criteria (in this case born in certain years) are entered and followed for many years gathering data about everything they can think of even if it just seems trivial.

That means El Marroun had built in access to a large number of 6, 7 and 8 year-olds where they already knew whether or not their mothers had smoked tobacco and/or marijuana before birth! A phenomenal opportunity.

Medical Marijuana During Pregnancy - Definite effects on developing brain of children
Medical marijuana use during pregnancy, definite alteration in developing brains of children

Previously the only way to see whether or not a child’s mother had altered its brain by smoking pot was in dead children by autopsy.

Now, the doctors wanted to use our new structural magnetic resonance imaging (MRI) machines to digitally reconstruct what the inside of the brains of such children looks like; and, because such mothers often also smoked tobacco, they wanted to see if there was any difference in them too.

They did find significant differences.

Findings: Marijuana v. Tobacco Exposed Brains

The Netherlands is a country where it is possible to observe the entire population at once; which is what the “Generation R Study” is doing with children observed from pregnancy.

Prenatal marijuana use was documented by maternal self-report and by doing urine testing. Tobacco use was documented prior to birth by questionnaires in each trimester and at birth.

This sub-study of 6, 7 and 8 year-old children gathered 113 unexposed “control” children, 96 “tobacco only” children and 54 “cannabis exposed” children. [Problem is that 74% of marijuana mothers also smoked tobacco, and of course nearly always continued smoking through pregnancy.] Only 15% of cannabis users didn’t smoke tobacco.

FIRST of all, corroborating many previous studies, smoking tobacco by mothers during pregnancy inflicted brain changes in their children which was observable at least 8 years later—loss of tissue in the frontal and superior parietal cortices (P < 0.001) and smaller brain volumes overall.

SECOND, the alteration of the brains of children whose mothers exposed them to cannabis during their gestation was different. Compared with the unexposed children, the cannabis children had much thicker frontal cortices (P < 0.001) and thicker frontal pole of the right hemisphere (P = 0.003).

These kinds of changes obviously didn’t bode well for the children so the researchers re-ran all their statistics trying to control for maternal education, household income, marital status, race, alcohol use, maternal psychopathology, the child’s IQ and birth weight—none of them abolished the significant association.

Huh? What Does This Mean?

"This is your brain on drugs" goes for your baby too!
“This is your brain on drugs” goes for your baby too!

The BIG THING is that: the brain is the target of drugs to do damage and the unborn, as usual, are in the cross-hairs for substantial and significant damage. “This is your brain on drugs” not only goes for you but your unborn child as well!

More specific than that, you’ll need to look at the many other studies which have already documented that children of marijuana users have increased aggression, problems with attention and lower scores on language abilities, memory and abstract/visual reasoning.

What turns these findings into more of a “smoking gun” is that: these intelligence and behavioral difficulties are what we’ve already found out the altered brain areas control!

The pre-frontal area is involved in cognitive functions: the ability to suppress responses and thoughts, attention, higher-order motor control, and working memory. [Well… if it walks like a duck and quacks like a duck…]

Unanticipated “Twists”

One of their statistics seem to show just why it’s been so hard previously to document brain changes—Smoking tobacco thins the baby’s brain while smoking “weed” does something that thickens it! And, nearly all marijuana users smoke tobacco too.

Those seeking to detract from the arguments and justify the use of cannabis often want to discount the results by claiming that “we just don’t know which it is the tobacco or the cannabis,” this research proves alterations in two different directions. A larger sample of “cannabis only” children [the very thought of that gives me grief] will surely only serve to make the statistics even stronger.

There is some more work that can be done on the next installment of this study. Cannabis use was only assessed in the first trimester, information wasn’t gathered in the “Gen R” study for the 2nd and 3rd trimesters. The authors could make efforts to retrospectively obtain that information on study participants.

And, of course, this study only represents “one point” along the child’s life-trajectory. A follow-up MRI in a few years along with correlation to school/social performance could be invaluable.

What The Researchers Suggest

The conclusion of the researchers: “These findings support the importance of preventing and reducing smoking cannabis and cigarettes during pregnancy.”

Ya think?!


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