I think that people who are suffering with anxiety disorders don't acquire them through using marijuana, but as teens self medicate by using mj and alcohol. Many adults don't listen to teens and kids who are anxious or/and depressed (I know this from experience) so this leaves the youngster to find a way of dealing with horrible feelings on their own. As anxiety and depression are usually in our genes, this will show up in adulthood regardless of whether or not the person had self medicated in their youth.