Cigarettes Linked to Lower Grades in Adolescents, Not Cannabis

In a recent study amongst teenagers, researchers found cannabis did not lower IQ or educational performance, but cigarette smokers had lower grades. Similar studies in the past have claimed cannabis lowers IQ in adolescents, overlooking tobacco as a confounder that could skew the results.

The mainstream authorities on drug abuse will have you believe that smoking pot in high school leads to a life of ignorance and poor achievement, but older medical studies don’t account for factors like cigarette use, alcohol and developmental influences. As public opinion sways towards cannabis, the new generation of drug policy officials and psychopharmacologists are demanding newer and more robust epidemiological analyses of substance use in the developing mind.

Evidence shows adolescence is a key point in mental development when drugs can influence long-term mental abilities. The Dunedin Longitudinal Study cohort study from 2012 indicates that starting to smoke pot on a regular basis later in life does not lower IQ long term, but adults who started smoking as adolescents showed significant decline with the passage of time. Publications by Dr. David Fergusson in New Zealand (strong proponent of the “gateway drug theory” for cannabis, have claimed smoking marijuana makes an adolescent more likely to drop out of school or perform poorly overall. These analyses have adjusted for confounding factors like socioeconomic status, but often overlook other substances a teenager may consume, like nicotine.

The analysis used information collected from 2235 adolescents part of the Avon Longitudinal Study of Parents and Children. 24 % tried cannabis by the age of 15, and over 90 % of them reported mixing cannabis with tobacco. Those who had consumed cannabis more than 50 times by the age of 16 scored 11 percentage points less than never-users when adjusted for performance at age 11. Contrary to evidence that nicotine produces a transient improvement in cognitive abilities, cigarette smoking dropped IQ and educational performance in those that had never tried cannabis. After adjusting for this effect, cannabis had no effect on either IQ or educational performance by age 16.

The fact most people in England mix tobacco and cannabis makes it hard to isolate the effects of cannabis from those of nicotine. Regardless, tobacco consumption alone produces cognitive decline without cannabis. A study from 2012 found twins with identical genetic code who either smoked cannabis or didn’t perform differently in school. Though tobacco isn’t significantly psychoactive, its detrimental influence on brain chemistry in adolescents may be more impactful than that of cannabis.

This latest study from England offers interesting insights into the effects of tobacco and cannabis, but has its downsides as well. The fact that most people mix weed or hash with tobacco in Europe means confuses any analysis. To fully assess the longitudinal effects of cannabis, nicotine and alcohol on developing minds we need to turn our heads to a place where people consume them separately: the USA.

Photo Credit: Anastasia Young 14er Holistics


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