As they take their first steps over the proverbial hill and pass their four-decade milestone, adults who spent their teen years smoking marijuana are at greater risk of seeing their IQ tumble, according to the results of a new study. If true, this would suggest that pot smokers are more likely to suffer from poor memory, impaired reasoning and short attention spans in later life.
Published in Proceedings of the National Academies of Science, the study apparently confirms what the researchers have labeled the “toxic effects” cannabis has on the human brain. With levels of cannabis use among US teenagers known to be once again on the up, the group is calling for extensive efforts to ward youngsters away from the drug and make marijuana less readily available.
According to the researchers behind the study, “The findings are consistent with speculations that cannabis use in adolescence, when the brain is undergoing critical development, may have neurotoxic effects,”.
The study was carried out on a sample group of 1,037 children born between 1972 and 1973 and tracked for 38 years. All participants were extensively tested both before their teenage years and once again upon turning 38, in order to measure cognitive performance.
During the course of the study, the sample group was also periodically asked about if and how often they used drugs recreationally. Those known to smoke marijuana were then categorized in terms of how heavy their usage of the drug was, ranging from infrequent use to full cannabis dependency. The way in which the cannabis users’ cognitive ability progressed and developed was then held alongside that of the group members who had never smoked marijuana.
The results of the study appear to confirm that the individuals who used cannabis from the earliest ages and on a more frequent basis demonstrated the greatest deterioration in cognitive function. Furthermore, while the members of the group who didn’t smoke cannabis were found on average to increase their IQ only a single point or less between the ages of 13 and 38, frequent marijuana users saw an average of five to six IQ points taken from their previous scores.
In addition, participants with a history of moderate to heavy usage of marijuana were found to score lower in speed of processing tests – again with the most significant deterioration being present in those who started smoking pot at an earlier age.
The study was also take further to include the thoughts and opinions of those closely familiar with the parties involved in the study, who backed up the results of the cognitive tests with their own reports of visible attention and memory impairment.
Concerns are once again growing that the problem is only likely to intensify over the coming decades as marijuana becomes more readily available and stronger than ever before. The study is also likely to be used as further ammunition for anti-marijuana-legalization campaigners who have long struggled to back up any long-standing theories on cannabis with hard scientific evidence.