Teenagers who use only cannabis appear to function better than those who also use tobacco, a new Swiss study suggests.
Such users are more socially driven and have no more psychosocial problems than those who abstain from both substances, concluded the study published in the November issue of the Archives of Paediatrics & Adolescent Medicine.
Cannabis or marijuana is the illegal drug most commonly used by youth.
"The gateway theory hypothesizes that the use of legal drugs (tobacco and alcohol) is the previous step to cannabis consumption.
"However, recent research also indicates that cannabis use may precede or be simultaneous to tobacco use and that, in fact, its use may reinforce cigarette smoking or lead to nicotine addiction independently of smoking status," the authors wrote.
Researchers at the University of Lausanne in Switzerland analysed data on Swiss students aged 16 to 20. The sample of 5,263 students included 455 who smoked marijuana only, 1,703 who smoked marijuana and tobacco, and 3,105 who abstained from both.
The survey found that, compared with students who used both substances, students who smoked only marijuana were more likely to be male, play sports, live with both parents and have good grades.
They were also less prone to alcohol consumption or using other illegal drugs.
Although teens who smoke both marijuana and tobacco seem to have more psychosocial problems, those who smoke only marijuana also needed close monitoring and counselling, the study said.
"Even though they do not seem to have great personal, family, or academic problems, the situation of those adolescents who use cannabis but who declare not using tobacco should not be trivialised," the authors concluded.