"The study examined people who began regular cannabis use in high school or in their early 20s" I think this study should be taken with a grain of salt because

"The study examined people who began regular cannabis use in high school or in their early 20s" I think this study should be taken with a grain of salt because of that statement right there. High school and even early twenties, we are still developing, and not everyone is going to develop to full adulthood by their early 20s. Anything that influences brain chemistry at that young age - be it drugs, hormones, etc. - is going to have lasting effect. I hope this leads to more studies about people who started later in life, say 30.