Dr Gary Chan, from the UQ National Centre for Youth Substance Use Research, spoke to Triple J's Hack about his latest research into cannabis use.
Back in 1992, a team of Melbourne researchers recruited around 2,000 high school students, all roughly 15 years-old, for a study about cannabis use.
They wanted to know whether smoking weed regularly in your teens, and early 20s, would have any lasting consequences later in life.
For the last 20 years, they've been tracking those kids - and their cannabis use - into adulthood.
And now the results are in.
Dr Gary Chan is the study's lead author, and works with University of Queensland's National Centre for Youth Substance Use Research.
He told Hack there is already pretty strong evidence to show how harmful cannabis can be for teens, during that crucial stage of neural development.
"The key message of this study is that there is also an elevated risk of a range of adverse outcomes for those who started using cannabis regularly in their early 20s," he said.
Other media
ABC Radio
Dr Chan also spoke to Caroline Winter on ABC Radio's current affairs program The World Today. You can listen to the interview here (starts at 17:20).
Cosmos
Science magazine Cosmos also covered the research with their article Toking takes toll.