“We found people who used cannabis and amphetamines at 30 had substantially lower levels of life success,” lead author Najman said in a press release.
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But there’s a catch. The dataset was highly local to Australia and some of it dates back to 1981, so it might not reflect modern experiences elsewhere. Plus, the researchers didn’t fully account for whether participants were using other drugs alongside cannabis, leaving a question mark over the findings.
“We do not have adequate data on other illicit drugs that may be being used, for example, ecstasy, opiates and even synthetic drugs,” the study notes. “A subset of those using cannabis as well as amphetamines may also be using a range of other drugs and it may be that our findings reflect polydrug use generally rather than the specific use of cannabis and amphetamines.”
Social context
The study also highlights a wider social context. Legal trouble, school struggles, and antisocial behavior can exacerbate the effects of drug use, creating a self-fulfilling cycle.
“Antisocial behavior and contact with the criminal justice system are the strongest predictors of continued drug use, along with problems at school and aggressive or delinquent behavior early in life,” Najman said. “These findings raise the possibility that targeted interventions for children who show early signs of antisocial behavior or poor school performance may reduce drug use and lead to improved life success.”
Interestingly, some research even suggests that occasional cannabis use can boost quality of life, meaning it’s not inherently destructive. The main takeaway appears to be timing and moderation: experimenting when young may not derail your future, but long-term adult use could come with serious trade-offs.
Australia, where the study was conducted, remains more restrictive on cannabis than many other countries, which may also affect the findings. In Australia, growing cannabis for personal use is still illegal across nearly all states and territories — the only exception being the Australian Capital Territory.
