Can you cite a source for your understanding of the literature?

At least a few studies disagree with you about adult onset, and it does appear that adolescent use amplifies the effects, but is not the only factor:

https://jamanetwork.com/journals/jamainternalmedicine/fullar...

https://www.nature.com/articles/tp2015201

https://www.sciencedirect.com/science/article/pii/S2352250X2...

The last one is a review article.

Not in a position to respond longer right now, but that last study you referenced is actually one of the ones I had in mind, in that there is not evidence in this literature review for long-term effects after cessation.

The first study there shows some evidence of performance decline after cessation, but they do not eliminate adolescent users. The second study was unable to distinguish brain structure for users that had ceased consumption from normal brains.

I definitely was not trying to suggest that there are no cognitive impacts on current users.

Oh, ok. I think we are in agreement - I didn't mean to suggest that there were long-term effects years after quitting, but that there are long-term effects of use - which perhaps I should have described as "effects of long-term use."

I agree that the jury is not in yet on whether there are long-term effects years after cessation except for adolescent use (and - by the way - old people: if you are over 70, smoking pot does appear to retard dementia and cognitive decline).