Study suggests regular pot smoking can lower IQ
FRIDAY, AUGUST 01, 2014 10:15 AM

The legalization of marijuana in some U.S. states has many parents wondering what they'll do about their children. If teens can legally smoke at a certain age, how are parents supposed to deter them? And do they want to? Proponents of legalized marijuana tout its natural origins as "healthier" than other substances, but opponents aren't so convinced. Now those who are wary of pot smoking have some backup. According to a study published by the Proceedings of the National Academy of Science of the United States of America (PNAS), consistent pot usage, beginning from a young age, can dramatically decrease a person's IQ score.

Varying levels of usage
The longitudinal study, conducted by Duke University researchers, tracked more than 1,000 New Zealand residents from the time they were age 13 through age 38. The researchers marked the amount of cannabis the participants smoked at 5 points in the 25-year period: at ages 18, 21, 26, 32 and 38. Then, researchers compared brain tests taken before the study to those taken after the period ended.

The results found that the amount of marijuana a person smoked and when he or she began partaking ultimately determined how many IQ points that individual lost. Researchers broke down the wide range of different pot-smoking levels as such:

• Those who never smoked had a slightly higher IQ than those who did.
• People who smoked, though only occasionally, had an average of a one-point IQ decrease.
• Depending on how long they had been smoking, those who used pot regularly (defined as four times a week), saw an average decrease in IQ score of three to five points.
• Smokers who reported beginning in adolescence and continuing to be regular users throughout life saw the most dramatic effect - an average of an eight-point decrease.

The point decrease is a reflection of IQ scores earned prior to and after the study. So if a person had an IQ of 100 at age 13 and smoked consistently thereafter, his or her IQ at age 38 could possibly be as low as 92.

Protecting IQ
Of course, the study results display an average IQ reduction. Individual results are sure to vary. However, the study is a good indication that smoking pot regularly from a young age onward can have serious mental consequences.

"Clearly what this [study] shows is that the people we need to be worried about the most are the ones that start the youngest and smoke the heaviest, during their teenage years," Dr. Timmen Cermak, an addiction psychiatrist and author of the book, "Marijuana, What's a Parent to Believe?," told NBC Bay Area affiliate KNTV.

This information, perhaps, is enough for parents to use to warn their children.