One-time ganja use may alter teen's brain


One-time ganja use may alter teen's brain

Dr Derrick Aarons

Sunday, July 21, 2019

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MANY research reports have revealed that the most harmful effects of ganja on users are to be found among teenagers.

In 2015, the American Academy of Pediatrics published a technical report stating that children and adolescents may be harmed when adults have easier access to marijuana for medical and recreational purposes. It further stated that campaigns to decriminalise or legalise marijuana could have the effect of persuading teenagers that marijuana is not dangerous, and this could have a devastating impact on their lifelong health and development.

Prior to that, in an article published in the Sunday Observer on March 1, 2014, before the decriminalisation of ganja in Jamaica, the country was warned thus:

“We need to be pre-emptive in our approach as we contemplate decriminalising ganja in Jamaica, and we must concomitantly discuss the safeguards we need to implement to protect our children. Symptoms of children exposed to marijuana are varied, but are primarily neurologic. Lawmakers should therefore consider specific requirements when drafting marijuana legislation to minimise the effects on children. Such requirements would include child-resistant packaging, warning labels, and public education.”


In Jamaica, we do a very poor job of protecting a significant portion of our children, and in respect of the inhalation of ganja, a major challenge is how to reduce contact between children and ganja within the home, or eradicate the belief that 'a little weed good fi di youth dem'.

Ganja affects children's ability to learn, thereby blighting their future prospects for effectively competing intellectually in the global marketplace. The report of the American Association of Pediatrics reminded that marijuana can affect memory and concentration, and interfere with learning in children and adolescents — making it harder for them to complete high school or pursue a university degree.

Ganja negatively affects short-term memory, and since learning involves information (knowledge) initially being stored in short-term memory for a couple of days before it is transferred to long-term memory in the brain for permanent storage and recall, then ganja impairs learning and the acquisition of knowledge. Hence, smoking or ingestion of ganja adversely affects our youth at a critical juncture in their education.

Other effects

A study by a team of researchers at the University of Montreal in Canada and published in the June 2018 edition of JAMA Psychiatry, revealed that the use of marijuana is harmful as it directly initiates a risk for psychosis in teenagers. So all young users of ganja risk developing psychotic illness.

Further, alterations in muscle motor control, coordination, judgement, reaction time, and tracking ability have all been researched and documented, and these may contribute to unintentional injuries and deaths among adolescents and adults if they drive motor vehicles while being intoxicated by marijuana.

Now, further research published this year has revealed that even a one-time use of ganja may alter the brain of teenagers. The research found that there was significant alteration of the grey matter volume in several parts of the developing brains of teenagers. After analysing data from a large research programme assessing adolescent brain development and mental health, the researchers found that the regions of the brain that were rich in cannabinoid receptors were significantly affected in teenagers who reported very little cannabis use.

A single use

While many investigators in the past had looked at the effects of heavy marijuana use on the brain, the effects of light use were understudied. Previous studies had shown both increases and decreases in human brain volume due to marijuana use, but most of these were in long-term, heavy users of marijuana who also smoked and drank alcohol.

There was, however, some research in animals which showed that even a single administration of marijuana might actually have an effect on their abilities and on their brain.

Researchers from the Department of Psychiatry at the University of Vermont in Burlington, USA, published their research findings in the Journal of Neuroscience this year. They had a very large sample of research participants, and so were able to search for teenagers who had reported very light use of marijuana.

Using data from the IMAGEN research project, which included 2,400 participants, the researchers identified those who reported only one or at most two instances of marijuana use. They were then matched with control participants using a variety of variables to effect scientifically reliable results.

Brain imaging

MRI scanning of the brain was then done on research participants at all eight of the IMAGEN research study sites, and voxel-based morphometry was used to compare the results. In addition to the alteration in the volume of grey matter found by the single use of marijuana, users of marijuana also scored higher in sensation seeking and in some anxiety measures when compared to non-users.

Some other studies have suggested brain shrinkage in the temporal lobes for individuals who have used cannabis. Consequently, more research is being recommended in this greatly under-researched area of marijuana usage.

Certainly, however, the Government must belatedly conduct an effective public education campaign on this critical matter!

Dr Derrick Aarons MD, PhD, is a consultant bioethicist and family physician; a specialist in ethical issues in health care, research, and the life sciences; the health registrar and head of the health secretariat for the Turks and Caicos Islands, and a member of UNESCO's International Bioethics Committee.

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