Look up marijuana studies on monkeys. They were suffocating monkeys with marijuana smoke. And the conclusion was marijuana. Kills your brain cells. now, when you die of no oxygen. What happens is your brain cells die first so thats how the whole Marijuana kills your brain cells thing came about. 

 Same with that rat cocaine experiment, turns out if you don't keep them in cages, they never take cocaine again. 

 That was an interesting concept. Ima revisit that one to remember it good 👍🏾