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The number of teenagers smoking marijuana has increased dramatically compared to the number of teenagers smoking cigarettes, as per a recent survey done in the US. But smoking weed as a teenager can damage the IQ and cause memory and attention problems.

Recent reports have shown that adolescents are starting using pot at younger ages and many of them smoke it on a regular basis. Teenagers believe that smoking marijuana is less harmful than smoking cigarettes and hence, more and more of them are making the switch from cigarettes to weed.

A scientific proof on the long term impact of smoking weed

A new study, published in the August issue of the journal Proceedings of the National Academy of Sciences, was taken up in order to find the long term impact of smoking weed on the neuropsychological health of the concerned individuals.

In the largest study of its kind, more than 1000 individuals born in the New Zealand city of Dunedin, in 1973, were followed up till the age of 38. All the participants of the study underwent an IQ test at the age of 13 and again at the age of 38. They were subjected to different psychological tests to assess their memory, power of reasoning, ability to visually process a piece of information, and the processing speed, when they reached the age of 38.

The participants were also questioned five times regarding marijuana usage between the ages of 18 and 38. The relatives of the participants and other people knowing them were also quizzed about the marijuana dependency of the participants and any noticeable memory and attention problems in them.

The researchers found that by the time the participants reached the age of 18, 52 had already become dependent upon marijuana. 92 other participants became dependent upon marijuana at a later stage of the study. In what can be termed as a significant finding, the researchers noticed a fall in the IQ levels of participants who had started smoking weed before the age of 18. Those participants who were found marijuana dependent in three or more surveys had a drop of almost 8 points compared to their IQ in the initial survey done at the age of 13. In other words, their IQ levels had dropped from being in the 50th percentile to being in the 29th percentile.

This drop in the IQ was permanent, i.e. it didn’t improved even if the participant had given up on weed by the time he reached the age of 38.

This decline in IQ was not observed in the participants who did not smoke weed until they were adults with fully developed brains.

The participants who smoked marijuana at least once a week for a minimum of one year, also showed a similar decline in their IQ levels. This damage to IQ was not found to be associated with the amount of weed consumed at one go or its potency.

The fall in IQ level cannot be underestimated as it affects various aspects of a person’s life, starting from his education to his income and overall quality of life.

Cannabis Can Be Neurotoxic When Taken Before The Brain Has Fully Developed

Researchers have opined that cannabis can be neurotoxic when taken before the brain has fully developed. Before the age of 18, the brain is undergoing constant remodeling and is not fully organized. Therefore, it is more vulnerable to be damaged when it is repeatedly exposed to harmful substances like cannabis.

In the above mentioned study, the relatives and other acquaintances of the participants reported that heavy addiction to cannabis led to cognitive problems associated with attention and memory. The participants faced difficulty in concentrating and suffered from forgetfulness. It was seen that even after quitting cannabis, the neuropsychological decline observed in teenage-onset cannabis users, was not completely restored.

People often say that teenagers who abuse drugs do not attain all the things in life that they were capable of. The results of the study prove the reason behind this belief. Men with lower IQs begin their career from a position of disadvantage and therefore lag behind their peers.

Studies done in the past have shown that cannabis abuse at a young age can lead to long term psychiatric problems. Teenagers smoking weed are at a higher risk of developing some kind of psychotic disorder in their later life. Cannabis has also been found to possess carcinogenic properties.

Many people stay clear of weed as they fear it may lead to legal hassles. But it should be stressed that the health issues arising out of cannabis abuse should be the major deterrent for teenagers out to get some ‘high.’

Importance of educating the teenagers and their parents about the hazards of smoking pot

Not only is it important to educate the teenagers about the hazards of smoking pot, it is equally important to educate the parents about its pitfalls. Many parents think that marijuana is harmless. As long as their kids stay clear of cigarettes, they tend to turn a blind eye to marijuana abuse. For them, it is the hard drugs like cocaine and heroin that are a reason for worry. Spreading awareness about the fact that smoking weed can harm the brain of their adolescent children should wake them up from their slumber.

Marijuana abuse among teenagers is on the rise, as shown by a government study in June 2012. According to it, as many as 23% high school students have admitted to smoking pot recently. A report by The Partnership at has found that one in every ten teenagers, i.e. 1.5 million teenagers, smoke weed at least 20 times or more in a month. This rate has increased from 5% in 2008 to 9% in 2011. The report has also found that the monthly usage of marijuana has increased from 19% in 2008 to almost 27% in 2011.

The Partnership study has also highlighted another important fact. It says that teenagers who smoke pot are more likely to abuse other drugs as they grow up. According to the report, teenagers who smoked weed 20 or more times in a month have double the chances of abusing drugs like cocaine, crack or ecstasy compared to other teenagers.

A United Nations Office for Drugs and Crime (UNODC) global drugs report, published in 2011, states that about 125 to 203 million people worldwide between the ages of 15 and 64 have abused cannabis at least once in the last year. This comprises of almost 2.8% to 4.5% of the total population of the world.

The figures are alarming! Its time concrete measures are taken to educate the general population about the health hazards of abusing pot. Considering the effect of cannabis on the brain of teenagers, special policy measures should be adopted, which are specifically directed towards adolescents.

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  • “Persistent cannabis users show neuropsychological decline from childhood to midlife”, by Madeline H. Meier, et al, Published in the August 27, 2012 issue of the Journal PNAS, accessed on September 20, 2012.
  • “Teens who smoke pot can damage memory, intelligence”, by Kate Kelland, published in the August 27, 2012 issue of Reuters Health, accessed on September 20, 2012.
  • “National Study: Teen “Heavy” Marijuana Use Up 80 Percent Since 2008, One in Ten Teens Reports Using Marijuana at Least 20 Times a Month”, by Cassie Goldberg, published on May 1, 2012 at The Partnership at, accessed on September 20, 2012.
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