The effects that smoking marijuana have on the brain have long been fiercely debated, now more so than ever in the wake of the wave of legalisation happening over in America. Last year, a research study concluded that while cannabis can have real medical benefits, such as the alleviation of chronic pain, it did invoke paranoid, anxious thoughts in vulnerable people.

However this study, carried out by medical researchers at two American universities (Pittsburgh and Rutgers), followed 408 teenagers from the age of 14 through to 36. Just under a quarter of the participants were voracious stoners in teenhood and later life, under half were low or non-users and some only smoked during their teenage years, giving up as they got older.

It’s commonly thought that smoking a lot of weed while the body develops can have adverse affects on mental health later on in life. However, this study found that the teenagers who heavily indulged were no more likely to suffer from depression, anxiety or schizophrenia in adulthood. Even the scientists were surprised.

“What we found was a little surprising,” said lead researcher Jordan Bechtold. “There were no differences in any of the mental or physical health outcomes that we measured regardless of the amount or frequency of marijuana used during adolescence.”

Bechtold did warn against his team’s findings, which only analysed males. "We wanted to help inform the debate about legalization of marijuana, but it’s a very complicated issue and one study should not be taken in isolation."

Campaigns are growing for weed to be legalised in the UK, with many pointing to the fact that alcohol carries far greater health risks. But is that a reason for legalisation? Dazed 100 star Miles Teller talks in an Esquire interview about how getting stoned ruined his motivation. "I didn’t do a single play when I was in college, because all I wanted to do was smoke pot. I did zero extracurricular activities so I could get high."

We want to hear your stories - has smoking adversely affected you and your friends, or are you someone who thinks it’s relatively harmless? It’s a complicated issue with many contrasting pieces of scientific research and we’re keen to hear from our readers. Let us know.