Teenagers who use cannabis regularly risk performing less well in exams, a survey of UK adolescents has found.
But while heavy cannabis users (those who use the drug at least 50 times by the age of 15) appear to show “marginally impaired educational abilities” and achieve poorer exam results at 16, occasional adolescent cannabis use does not seem to lead to poorer educational achievement.
The research, carried out by the Avon Longitudinal Study of Parents and Children, tracked the health of children born in the Bristol area in 1991 and 1992.
The study, also known as Children of the 90s, analysed the data of more than 2,000 children. The youngsters had their IQs tested at the age of eight and then again at 15. Their GCSE results were factored in a year later and they were also asked about their cannabis use.
Researchers warned, however, that while regular cannabis use appears to be associated with “decreased intellectual performance”, it is difficult to separate its specific impact from other risky behaviours, like alcohol, cigarettes and other drug use.
“Adolescent cannabis use often goes hand in hand with other drug use, such as alcohol and cigarette smoking, as well other risky lifestyle choices,” explained lead researcher Claire Mokrysz, of University College London.
“It’s hard to know what causes what. Do kids do badly at school because they are smoking weed, or do they smoke weed because they are doing badly?
“This is a potentially important public health message. The belief that cannabis is particularly harmful may detract focus from and awareness of other potentially harmful behaviours. However, the finding that heavier cannabis use is linked to marginally worse educational performance is important to note, warranting further investigation.”
The study’s findings were presented at the annual congress of the European College of Neuropsychopharmacology in Berlin last month.