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Brain-numbing drugs – The effects of alcohol and cannabis on cognitive pathways

October 15th, 2018 | by Eleanor Gratton
Brain-numbing drugs – The effects of alcohol and cannabis on cognitive pathways
Science
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We all know that as you enter Castle Leazes, two of the most common things are the not so distant sounds of drum and bass signalling the start of a boozy night out, and the smell of spliffs drifting across the cow field. Therefore, it comes as no surprise that alcohol and cannabis are two of the most commonly used drugs among teenagers, with a Canadian study revealing that out of nearly 4000 students, 28% admitted to cannabis use and 75% said they drank alcohol at least occasionally. The study also brought to light unexpected results, with cannabis turning out to be ‘more harmful’ to teen brains than alcohol. However, when looking into the results and conclusions, how reliable really is this study? And realistically, will it change attitudes towards two drugs that are becoming ever increasingly normalised in teen culture?

The research, carried out by the University of Montreal, analysed the drug and drink habits of teenagers and the relationship this had with their cognitive development; i.e. the construction of thought processes, problem solving and decision making. The study was published in The American Journal of Psychiatry, with the objective to investigate if there was a relationship between alcohol or cannabis use and cognitive development, and if so how much of an effect the substances had.

3,826 students across the Greater Montreal region (which amounted to 5% of all students entering high school in 2012 or 2013) had yearly tests over a four year period on their alcohol and cannabis use, using school based computerised cognitive tests. These tests included recall memory, perceptual reasoning and working memory, and were carried out separately for each substance and tested each cognitive skill.

The results differed from expectations, with lead study author Professor Patricia J Conrod saying she expected alcohol to have more of a detrimental impact. However, results showed that whilst both alcohol and cannabis have detrimental effects in all cognitive domains, cannabis had significantly worse short and long term effects. This included higher rates of errors in the tests taken by teenagers using cannabis, both whilst and after stopping taking the drug, which wasn’t shown with alcohol consumption.

This is the result of cannabis affecting cannabinoid receptors located in the brain, which sub-serve the function of mediating movement, mood state and decision making skills as well as high level of consciousness, particularly in the hippocampus (one of the areas of the brain responsible for memory). This is because THC (tetrahydrocannabinol), the substance present in cannabis that is responsible for feelings of euphoria, suppresses the firing of neurones. Neurones are responsible for transmitting signals in and around the brain and the rest of the body, and therefore their suppression leads to the impaired cognitive skills.

These results led the researchers to urge teens to delay their use of cannabis for ‘as long as they felt able’, but a criticism of this conclusion is that it gives the impression that the use of cannabis is somehow inevitable. Furthermore, since only 5% of the population entering high school was tested, is this really a big enough sample population to conclude the effects of these drugs on an entire age bracket?

Other criticisms of the paper included the socioeconomic status of the teens used as a sample of the population. For example, 69% were living with both biological parents and so may make different lifestyle choices to teens who only live with one biological parent, therefore making the results not a true reflection of the whole population.

The findings of this study further confirm that substances such as cannabis and alcohol can have adverse effects in an organ that is essentially the control centre for our whole body. However, with intensive alcohol use already normalised in teen social circles, and the use of cannabis becoming ever more common when we all already know the risks in the 20 drug safety talks we’ve had, will the results of this study have an impact?

 

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