Several studies have previously argued that cannabis lowers IQ levels. For instance, a large New Zealand study of 1,000 individuals measured the IQs of participants at the age of 13, and again at 38, while assessing pot smoking habits in the interim period. The study found that individuals who had reached the age of 18 and had become addicted to cannabis experienced a drop in their IQ scores when measured again at the age of 38. According to this study, it does appear that cannabis lowers IQ.
Although this study has been criticized as it did not control for other life choices during the two IQ testing periods, it has corroborated previous studies find also speculated that cannabis lowers IQ.
A new Canadian study also examined whether cannabis lower IQ. The eight year study followed 70 teenagers, who had their IQ tested at the age of 12 and again between the ages of 17 and 20. The study found that teenagers who smoked more than five joints per week experienced an average IQ drop of 4 points. Although this may not sound like a big drop, it’s important to be reminded that 50% of the population have IQs of less than 100. So losing four points will not provide do anyone any favors.
Cannabis lowers IQ, but also increases the chances of developing a mental illness
The message is clear: Cannabis lowers IQ. And this body of research comes on the heels of other scientific investigations including a study of 2,000 teenagers which demonstrated that teenagers who have smoked marijuana more than 5 times were twice as likely to experience psychosis in the following 10 years as those who did not use cannabis. In turn, people who experience psychosis are more likely to go on and develop schizophrenia.
Schizophrenics are also well known to experience substantial drops in IQ throughout their lifetime.
What is clear is that cannabis lowers IQ, but it also increases the chances of developing mental illnesses which have also been shown to lower IQ. When it comes to the brain and smarts, cannabis is not friend.
You can test your fluid intelligence here at www.iq-brain.com