http://www.druglibrary.org/schaffer/hemp/amot1.htm

As far as amotivational goes..no bro. This information is credible.

It does not appear as though the amotivational syndrome is all that common among marijuana smokers. In one survey[2] a sample of almost 2000 college students was studied. There was no difference in grade point average and achievement between marijuana users and nonusers, but the users had more difficulty deciding on career goals, and a smaller number were seeking advanced professional degrees. On the other hand, other studies have shown lower school averages and higher dropout rates among users than nonusers. In any case these differences are not great. If there is such a thing as amotivational syndrome, its affects appear to be restricted to a few individuals, probably the small percentage who become heavy users.