I know at least 8 people that are 35 to upper 40’s, one that is about 60 years old and they have smoked pot several times a day, every day (with a few exceptions) since junior high school.
They all have said that they feel like they should take a break for a while. The only time they have indeed taken a break is for a couple of months before a new life insurance health check up, for a week on vacation where it just did not feel safe to travel with it, and one that got caught and had to go to get tested almost two times per week for six months. Two just stopped for 13 months just to do it.
They all report the same experience: Not easy to sleep for a few days, dreams get more vivid after about a week, not much appetite. Everything is so slight that if one were not trying to detect any change, it might not even have been noticed.
The problem is that causes the most trouble is NOTHING! That’s right, they all got pissed off because the clouds did not part, car keys would still occasionally get misplaced, an item forgotten at the grocery store - of course 4 of them were almost straight A students, and 4 were straight A’s in graduate school too! - So much for the brain damage bit - If these guys were awake, they were high - except when in class (most of the time) or while studing/writting papers.
It seems that the pot smoke has much more tar, but because it is not consumed in nearly the quantity of cigarettes, and it is often filtered through water, a heavy daily smoker is probably getting the equivalence of just a few cigarettes per day, just empty the tobacco out of a pack of cigarettes into a bag, it would be a fat bag.
One of those friends has an article from some professional medical publication about medical imaging that revisited the “this is your brain on drugs” experiment of the 70’s, using PET. They noticed changes in blood flow but could not find any harm and the report sounded so good for pot that they had to include a comment that said this does not mean we can give pot a clean bill of health.
Alcohol is far more toxic that THC. It has been said that there has never been a death from THC overdose. Just watch one drinking all night and one that has been smoking all night - alcohol changes a person way more than pot ever will. --Shoot there is a commercial on TV right now about the tens of thousands of deaths from “medicine” - legal stuff.