Inhaling combustible plant material is bad for you, period. Yes, it can cause cancer, although one reason the risk isn't as high as with tobacco is that nicotine prevents your lungs from getting rid of the tar through vasoconstriction, while thc is a vasodilator so you don't have quite the same problem. But smoking anything is bad for you, and there can be no disputing that. Doesn't mean I don't do it from time to time, but there's no use deceiving oneself.
But the biggest negatives of weed are due to the fact that it's smoked, not the actual drug itself, which can be vaporized or eaten. Studies in short term memory and iq show that heavy marijuana use drops i.q. around 3-6 points in the short term, but if the user quits, then it quickly returns to the previous point.
Marijuana, like everything else, is best experienced in moderation, and I'm a firm believer that if you're going to put something into your body, you better have a damn good idea what it's doing to you.
Im not saying smoking is good for you, but its not the only way you can use cannabis, like you mentioned eating or vaporizing. Studies show that people who smoke tobacco and cannabis have lower risk of lung cancer than people who only smoke tobacco. Smoking tobacco causes cancer because of the radioactive incredients in it, not so much tar itself, but tar does you other bad stuff. Allso when you smoke tobacco, you smoke it much more than what you smoke cannabis, im not talking about one cigarette or one joint, but in x period of time.
Studies made in jamaica, where they dont mix tobacco with cannabis shows that they dont get more lung cancer than people who doesent smoke cannabis. Cannabis prevents cancer, because cannabinoids (that people naturally have) is killing mutated cells and mutated cells are what causes cancer. Cannabinoids in cannabis works the same way as your natural cannabinoids, the difference is in the amount and the fact that when you take cannabis it spreads to much wider area than your own cannabinoids.
What comes to memory drop, its
mostly because of being passive, cannabis itself does cause that, but its been scientifically proven that the difference is so small that it doesent show in eny way.
Different cannabinoids effect in your head different time, thc doesent effect long, but cbd that makes you stoned(instead high) when combined with thc effects longer. You can see it yourself, when you smoke several times a day and first time gets you more high feeling and later you get more passive(stoned), since cbd is still kicking. Cbd itself doesent have eny effect, but it alters the effects of thc and after there is so little thc left that you dont feel high, cbd makes the passive feeling stronger still, even if you arent high enymore, thats why you might feel bit tired the next day(and some maybe several days), unless you got used to smoking cannabis often.
Personally i think the greatest thing about cannabis is that it lets me used my not so strong cognitive functions without me using more energy on them. It kinda feels like it takes the energy away from Ti and spreads it more even with all of the functions. Allso it works bit like hallucinogens by seperating different functions, but not that strongly as hallucinogens does. This helps me develope and understand how different functions work better than without smoking.
Im not suggesting enyone to smoke cannabis, because its not good for you, unless your mental health is good, and you might not know about all the hidden shit you got in your head that cannabis might bring to surface. Alltho they might be good for you to treat those problems in the subconcious, even if you dont see them effecting you.