I take everything with a grain of salt. In the US only studies that produced / looked for negative results from cannabis use were funded by the government. That said, I have referenced many articles from JAMA and you can't just pick and choose the ones that have your desired outcome. I have yet to read this article, but I'm sure I'll learn something.
A huge point of consideration on any of these studies is the size of the trial group. Numbers and percentages can often be misleading. Like, 75% of participants reported a negative side effect...... only 4 people were in the study. There are many other factors that can be used and skewed to fit the results into the original hypothesis or desired outcome. This is why we desperately need human clinical trials with cannabis, real testing. I love the plant and think it has many, many benefits, but I don't doubt there are a few drawbacks. I'm all for research and education.