(CNN)Around the world tens of millions of people use cannabis.
It's legal for recreational use in 11 US states and Canada. In these and some other places, it's also approved to treat some medical conditions.
But a new analysis highlights that the debate over marijuana's health risks and benefits is complicated and depends on the active compounds involved.
A review of existing research published Tuesday found that a single dose of the main psychoactive ingredient (THC) in cannabis -- equal to one joint -- in otherwise healthy people, can temporarily induce psychiatric symptoms, including those associated with schizophrenia.