Can smoking pot really make a person less intelligent? There are many rumors and stigmas behind the effects of marijuana on a human. People have made the claim that smoking the drug after a long period of time will in fact lower your IQ (which yes, does not necessarily determine how smart a person is but it is a method of doing so).

According to a survey done in the summer of 2013, almost 40% of Americans had tried marijuana. Nowadays, the drug is even legal to smoke and use in a few states in America. This drug comes from Cannabis indica plants. These plants contain over 500 chemicals in them including tetrahydrocannabinol or THC. THC is the well-known culprit for the greatest effects on the brain due to marijuana . THC attaches to cannaboid receptors, activating the brain’s neurons and interfering with normal functions. The cannaboid receptors found in the brain, affect a person’s memory (specifically short-term as a majority of cannboid receptors are found in the hippocampus), thinking, concentration, and perception.

There are studies in which have decided to analyze the suggestion that smoking marijuana does lower a person’s IQ over time.

To begin, experimental studies were performed on lab rats to examine the effects of marijuana on their brains. It was shown through the studies with laboratory mice that those that were exposed  to marijuana on a regular basis from an early age had smaller orbital frontal cortexes (which are in charge of decision-making) than those who were not exposed frequently or at all to the drug. This study does not prove the mice were then less intelligent than the others but was interesting enough for researchers to note as the shrinkage of the brain is something to be tentative about.

Researchers from the University College of London tested around 2,600 participants in Bristol. They checked the participants’ IQs at age 8 and then at age 15. Those who were recorded to have smoked the most frequently and largest amounts did not have lower IQs years later than those who did not smoke or smoked occasionally all of those years. That being said, test results of the participants at age 16 of those who smoked the most were 3% lower.

A study was completed in which followed 1,037 participants from age 13 to the age of 38. They were from Dunedin, New Zealand. Their dependency on marijuana was evaluated at ages 18, 21, 26, 32, and 38. The groups were divided by dependency- nonusers, those who smoked an average of once a week, those who smoked an average of twice a week, and those who smoked an average of 3 or more times a week. After years of testing, it was found that those who had a physical dependence on the drug before the age of 18 had an average decrease of 8 points in their IQ by the time they reached the age of 38. Despite this result seeming drastic, it only occurred to 38 people out of the 1,037 tested. This result is significantly small. In addition, those with lowered IQs smoked much more frequently, smoking marijuana on average 4 days a week.

Dr. Malik Burnett, a renowned researcher in the field, claims “follow up studies of this data have shown that differences in socioeconomic status may account for the differences in IQ found in the study, not to mention the discussion surrounding IQ as a valid measurement of brain function and intelligence which are beyond the scope of this response.”

Many socioeconomic factors seem to have a possible effect such as education levels, employment history, and childhood traits

Another study completed in 2002 measured the IQ’s of 70 people. They first had their IQ’s tested when they were ages 9-12. Their IQ’s were then taken again when they reached ages 17-20. Heavy users (smoking 5 joints or more a week), light users (smoking less than 5 joints a week), and non-users were separated into groups. It was found that heavy users IQ scores were an average of 4.1 points lower after years 8 years of smoking while light users IQ scores were an average of 5.8 points higher after 8 years of smoking. Non-users IQ scores were found to have risen an average of 2.8 points interestingly enough (did not increase as high as light users). It has been found from this study that heavy users are really the ones affected.  It is quite strange there was a correlation between light smokers and there IQ’s rising much more on average than non-users.  These results could be a fluke or due to chance most definitely.

 

 

 

There are too many confounding variables that could be responsible for these results. Some results do suggest that a high use of marijuana does lead to lower IQ’s, but there is not much significant proof. In addition, how can anyone decide how much a person’s IQ really reveals about his or her intelligence. More studies must be done, but unfortunately it seems they must be performed over a large length of time. There seems to be a lack of evidence to support that marijuana does make people less intelligent or lowers their IQ’s (the null hypothesis). The correlation does not mean causation here. I would say it is not likely the Texas Sharp Shooter problem occurs currently because there are studies that support both sides of the argument. Null results have been published, eliminating the issue of the File Drawer problem. More research must be completed to find the biological mechanism as well.  Just be aware that smoking weed may have an impact on your IQ and/or intelligence.

 

http://www.livescience.com/24553-what-is-thc.html

http://science.howstuffworks.com/marijuana4.htm

http://marijuanahealthwellness.com/?p=1295

http://www.drugpolicy.org/blog/does-marijuana-kill-brain-cells

http://www.pnas.org/content/110/11/4251.full.pdf?with-ds=yes

http://www.washingtonpost.com/news/wonkblog/wp/2014/10/22/no-marijuana-use-doesnt-lower-your-iq/

http://sciencenordic.com/does-pot-really-make-you-dumber

http://www.cmaj.ca/content/166/7/887.full.pdf+html

http://www.latimes.com/science/sciencenow/la-sci-sn-regular-marijuana-shrinks-brain-20141110-story.html

http://cdn.urbanislandz.com/wp-content/uploads/2013/01/Snoop-Lion-Smoking-Weed.png.jpg

http://www.laszlolaw.com/wp-content/uploads/2015/06/marijuana-leaf.jpg

https://s3.amazonaws.com/rapgenius/PxpDB58cQOKPx9GmJxLa_getting_high_weed.jpg