Cannabis ‘more harmful than alcohol’ for teen brains

Ottawa: Teenagers using cannabis are causing long-lasting damage to their developing brains, a Canadian study suggests. It found the impact on thinking skills, memory and behaviour was worse than that of teenage drinking.

The researchers, from the University of Montreal, urged teenagers to delay their use of cannabis for as long as they felt able.

The study tracked and tested 3800 adolescents over four years, starting from around the age of 13. Drinking alcohol and taking drugs, such as cannabis, at a young age is known to cause problems with cognitive abilities such as learning, attention and decisionmaking as well as academic performance at school.

This study found these problems increased as cannabis use increased - and the effects were lasting, unlike those of alcohol. The teenagers, from 31 different Canadian schools, gave details of their drug and drinking habits once a year. Their brain skills were also tested every year in school using computerbased cognitive tests.

Developing brains

Although levels of cannabis use in the study were low compared with alcohol use, 28 per cent of the teenagers still admitted to some kind of use. This compared with 75 per cent of the teenagers who said they drank alcohol at least occasionally.

Prof Patricia J Conrod, lead study author, from the department of psychiatry at Montreal, said she had expected alcohol to have had more of an impact on the teenagers’ brains. But, instead, the research detected greater increases in errors in cognitive tests on the teenagers using cannabis - while they were taking the drug and after they had stopped.