A High to Remember

There has been a long debate over legalization, but is marijuana a good thing? Recent studies show that while certain chemicals in marijuana damage adolescent brains, they are beneficial to adults, especially those with diseases such as Alzheimer’s.

Veronica Campbell, a neuropharmacologist from Trinity College in Dublin, says that marijuana truly works both ways.

A recent study conducted by Campbell and her team used the tetrahydrocannabinol (THC) chemical from marijuana—the chemical responsible for the high—and tested it on newborn, adolescent, and adult rats. In the newborn and developing adolescent rats, THC exposure resulted in brain cell death. In contrast, it was not as detrimental to neurons in adult rats.

Why does this happen? “We don’t know,” said Campbell in an interview with Scientific American Mind. “It’s still being investigated.”

“The most psychoactive cannabinoid chemical [in marijuana]is tetrahydrocannabinol,” explains Dr. Jeffrey Henderson, director of Murine Imaging and Histology at U of T. “THC receptors in the brain are concentrated in the hippocampus (the part of the brain associated with long-term memory), amygdala (associated with processing the memory of emotional reactions), and the cerebellum (associated with motor controls and sensory perception), which are all affected when one gets high.” Henderson points out, “the most clearly confirmed medical benefits of marijuana are anti-nausea, enhanced appetite, and pain decrease, [yet]long term usage may still be toxic to the brain.”

Campbell’s recent study highlighted the overall effects of THC on the human brain. The “slaughter” of young neurons by THC, as Campbell calls it, could explain why some who smoked pot while pregnant have children with cognitive impairment and why some adolescent marijuana users show brain damage in their still-developing neural circuits.

As neurons mature and cells age, their biochemistry also changes. Endocannabinoids (the chemicals that regulate important functions in the brain, such as thought and perception) start to shift and regulate different functions. These endocannabinoids appear to assist in the survival of neurons in adults. This is extremely important in patients with Alzheimer’s disease, as it improves mental function by decreasing levels of the neurotransmitter acetylcholine, which contributes to memory loss. It also suppresses the toxic effects of the abeta protein, which kills brain cells.

Henderson explains, “THC acts by mimicking the actions of endocannabinoids, which normally exist in our brain. All of these agents work by suppressing a part of the normal inhibitory signals in our brains.”

“While there is some evidence to suggest that THC derivatives may reduce Abeta aggregates in culture, a number of the mechanistic aspects of how this occurs are presently unclear. There is evidence to suggest that THC derivative competitively stalls the enzyme acetylcholinesterase, as well as prevents Abeta aggregation, a key pathological marker of Alzheimer’s disease,” says Henderson.

Before we start encouraging Alzheimer’s patients to smoke up, Campbell told Scientific American Mind that “the beneficial effects of the THC are in much lower concentrations of the chemical that are found in the actual plant that people use to get high.”

A new challenge is to isolate the important chemicals of cannabinoids in marijuana and see which ones, including the THC molecule, have a protective effect on neurons.

In small doses, there are some components of marijuana that when cultivated properly, could be potentially lifesaving. Overall, raw marijuana is still harmful when used over long periods of time.

Numerous studies are still being conducted in this area, so it looks like smoking a bowl isn’t the answer quite yet.

– Article from theVARSITY.ca on November 16, 2009.



  1. Reverend J Shaffer on

    that if I hadn’t started smoking pot when I was 13, my IQ would be higher than the 135-143 range it is now? I can’t imagine how that’s even possible.
    Or, are “they” saying that the anger and bitterness, a direct result of my father having a heart attack & dying pretty much right before my then-10-year-old eyes, is actually a result of smoking the same Cannabis (a plant I didn’t discover until 3 years later) that has reduced my short-tempered-ness?

    To me, this sounds like the “Saccharine Scare” all over again. . .

  2. Anonymous on

    You’re completely right and the University of Saskatchewan used synthetic T.H.C. in their experiments and found neurogenisis in the Hippocampus.

  3. Anonymous on

    who ever said you dont grow new brain cells your an idiot marijuana causes neurogenisis the creation of new brain cells dont bass my post unless you kno what your actully talking about and yeah every time you goto bed more brain cells are created and some die off its a never ending process!

  4. Anonymous on

    “Overall, raw marijuana is still harmful when used over long periods of time”?! What constitutes a “long period of time” how is it harmful and how harmful is it? In what dosages and in what method of ingestion is cannabis harmful. Where can I find the study on this? I need specifics!

  5. Anonymous on

    In 2001, the U.S. Government, as represented by the Department of Health and Human Services, filed for and was awarded in 2003 a patent on cannabinoids as antioxidants and neuroprotectants. U.S. Patent 6630507.

    Why would a government agency grab a patent for something that has “NO MEDICINAL VALUE?!

  6. Anonymous on

    You don’t grow new brain cells. Once they’re gone, they’re gone for good. However, sometimes the remaining living brain cells “take up the slack” and learn to take over the duties of the now dead brain cells.

    Whenever I see these studies, the first thing I ask myself is: where is the information about alcohol use? What does alcohol do to rat brains as compared to marijuana (in doses equivalent to what people would take in the real world)? SOME people who smoke marijuana exhibit brain damage? SOME people who smoke marijuana become schizophrenic? I would hypothesize that these groups of people may simply be exhibiting the symptoms of alcohol abuse.

    What possible reason would the researchers have for ignoring the effects of alcohol? I would suggest the scientists who do negative studies about marijuana are alcohol-drinkers, not marijuana-smokers. Alcoholics are always looking for a way to play down the harm of alcohol.

    The entire anti-marijuana movement is fuelled by a pro-alcohol ideology. It’s a massive cover-up.

  7. Anonymous on

    This study really pisses me off because of the following a
    rats life cycle is way shorter than a humans
    an adolesant rat lost brain cells from THC how old was this rat right from the whom? how does an adolesant rat tie in with a child? there is no correlation between the two and how could you estimate an age that is exact of a child and rat?(ie. a 6 week year old rat equivalent to 6 year and 30 day old child) in brain devolopment you cannot just compare the two.It doesnt make sence, how were these doses administered? threw intravenous injection? No one on earth has ever injected THC via needle to get high! Is it possible that injecting THC striaght to the brain would cause a stir resulting in a loss of some brain cells? A rat that has no clue about nothing gets picked up by this huge person who puts needle into them and then procedes to watch and document them. That would be enough to induce severe anxiety in me which would cause me to lose a few brain cells i would imiagine. Besides there is no link between mothers smoking cannabis and their children have cognative difficulties it has been proven that THC does not cross the barrier into the baby. This study has way to many variables! The only proven fact here in this study is that THC does infact help Alzhiemer’s diease but to which multitude is unknown does it prevent or treat? more unbias research is needed!! BESIDES how are these people linking the loss of brain cells with cognitive impairment. Booze tv ciggarettes bumps on the head all decrease brain cells but over time these brain cells grow back.

    “the THC are in much lower concentrations of the chemical that are found in the actual plant that people use to get high” yea when your injecting the THC but not when your smoking it!!!