In one of our recent lectures the discussion was centered around tobacco and whether or not smoking is bad for you.  I thought the lecture was interesting because we learned more about the public perception of alcohol decades ago and how it has changed today.  The acceptance of cigarette smoking throughout adults in American society was pushed on the public by tobacco companies and doctors themselves which is crazy to think about.  Perhaps the most important reason this lecture resonated with me is because both of my mother’s parents, my grandfather and grandmother happened to pass away earlier than expected due to health conditions that were likely caused by their tobacco smoking habits.  One point of the lecture that stuck out for me was when Andrew revealed that studies done on men who smoked showed the lag-time between cigarette consumption and development of lung cancer to be 20 years apart.  This was surprising to me because of the fact that Andrew pointed out that we know that there are many cases where regular cigarette smokers develop lung cancer later on in life, and there is enough data to support this idea as evidence of a correlation, but the problem is that there still is no known mechanism for what specifically causes people who smoke tobacco to develop lung cancer.  It is so widely assumed that smoking causes lung cancer that it is practically perceived as fact, when most people don’t even realize we don’t know WHY smoking causes lung cancer, we just accept that to be true because that’s what statistical data from scientific studies portray to us as evidence.

After this lecture was over I got to thinking about whether or not a phenomenon similar to this instance of tobacco smoking could be true for a different drug, and naturally I thought of the most commonly used recreational drug in America today, cannabis.  Cannabis is such a taboo subject because of all the new progress that has been made in scientific applications of the medical benefits of the cannabis plant. In America today there are 25 states that have legalized medical marijuana and even Washington D.C.!  Yet one of the most common arguments against legalization of cannabis is that the dangers of smoking pot at a young age are detrimental to the mental development of young adults.  For years this had just been a narrative pushed onto public opinion in different ways by different industries and organizations (like alcohol and tobacco companies, pharmaceutical corporations) and government bodies (DEA, FDA, etc.), but there was not really any hard scientific evidence to support this claim.  Recently I came across an article that proposed a reason as to why there might be merit to this age-old claim after all.

A new study conducted by researchers from Osaka University in Japan suggests that cannabis use at a young age can interfere with the development of brain connections.  The study determined that the human body has its own system of cannabinoids called endocannabinoids that are crucial to the development of neural connections.  The study suggests that smoking cannabis can be detrimental to this development, and furthermore addresses an even older question of how neural circuits in the brain are developed.  As a young human ages the brain undergoes major structural changes before maturing, and during this time the synapses (number and arrangement of connections between neurons) are restructured. This study found that this development process occurs in 2 stages; the first stage entails strengthening and creating new synapses, while the next stage involves a process known as synaptic pruning which essentially involves shedding unneeded synapses so that new neural circuits can be reorganized.  In order to study how this process is affected by cannabis the researchers used newborn mice and utilized fluorescent proteins to analyze neural activity in the brain of the mice, examining the development of thalamocortical axons (TCAs), which are nerve fibers that connect the neurons of the thalamus to the cortex.

As the study progressed, researchers observed new TCAs running from the thalamus to the cortex, however after a number of days this halted, and the synaptic pruning process began.  This shift of synaptic processes was due to an increase of type 1 cannabinoid receptors, thus implying that endocannabinoids are a key component in synaptic pruning.  In order to validate this speculation, the researchers used new mice who were genetically modified to lack CBR1s, and then delivered doses of THC (tetrahydrocannabinol – the psychoactive component in marijuana) into the brains of the mice and found that THC binds to CBR1s and interferes with proper synaptic formation.  The researchers concluded that because this synaptic formation process occurs during adolescence for humans that excessive consumption of cannabis (THC) for young people can cause cognitive impairment due to the potential lack of creation of new neural synapses, and accelerating the synaptic pruning process way before the brain is fully matured.

The conclusion of this study really intrigues me, because it really sheds new light on the age-old argument: is pot really bad for you?  Being completely honest, I know look back on my days in high school and in college and think about the times I’ve used marijuana before, and it really got me thinking about the real effects of this drug.  There is so much information and opinions out there about the true nature of cannabis, and this one study just made me further question the legitimacy of the “pot is harmless” argument.  I am fully in favor of the legalization of cannabis for its potential medical, and industrial applications as a natural resource, but I am not so inclined to believe that recreational cannabis consumption is truly “harmless” just because nobody has directly died from overdosing on THC.  In the future I really hope that the governing legislative bodies and executive agencies thoroughly assess this issue to try and make light of the situation and try to learn more about this fascinating plant.