My brother smoked marijuana just about every day from age 15 till age 40. He also ate poorly and drank too much alcohol sporadically (not daily however). He had a total mental breakdown a few weeks ago at age 40 and was diagnosed with marijuana induced psychosis and permanent brain damage, along with a personality disorder. Considering that he committed some serious acts of vandalism as well as an assault when he was in this state, he was incarcerated and is awaiting trial now.
I know that is hard to believe that much of this is due to his very regular use of MJ from an early age, but his team of medical experts repeatedly told us that this was their diagnosis. They said that there is increasing evidence that MJ use prior to adulthood can damage the development of the brain and that this damage may not show up for years or even decades. They also said that it's not a common occurrence but they do see these cases from time to time and my brother is a classic fit for this sort of thing.
The damage is permanent, according to them. My college educated brother will be in jail or in a mental institution for the next several years and his life is basically ruined.
Even with this situation, I am not condoning keeping MJ illegal. I am saying that people should not just assume that it's harmless. When people smoke it, they need to know the risks. It's not just a harmless little ol' weed.
Smoke at your own risk.
First of all, I am so sorry to hear about your brother, Kathryn. That must be so hard for you, right now. I hope that somewhere in his treatment for these issues he finds peace.
As to the marijuana issue, though, I think what leaps out at me is that your brother smoked every day. The few folks I've met who really and truly smoked every day (not just frequently, and not just having occasional periods in their lives of smoking every day, but who really smoke every day for extended periods, or even much of their lives) were personalities deeply prone to addiction, and had some fundamental instabilities in other ways.
Now, granted, marijuana is not physically addictive. But any potent substance can be psychoemotionally addictive for particularly addictive personalities. And I am not just dismissing the effect of smoking so much weed on your brother, or saying that his issues are purely inherent and internal, or anything of the kind. But smoking every day is far and away not the typical pattern of use for marijuana.
Any substance, legal or illegal, can be used responsibly or abused. And while I don't at all wish to denigrate or discount the very painful part that marijuana has apparently played in your family, I would be very hesitant to take such examples as proof of anything, or indicative of larger patterns.