Interesting find. I know people, successful people, in positions of education, medicine, and other careers making 100K+ annually for many years with no impairment. By no impairment, I mean their memory and decision making skills seem great with almost no fault. Brain damage, that's difficult to measure in these types of people. Perhaps, some are positively affected, while some are not.
Then again, I've known people that used cannabis and had problems in any type of school. The educated cannabis users often know how to control the habit, instead of the habit controlling them.