While i agree it is a rather old study, however 13 years isnt that old, considering not much has changed since 1996. The same methods of use are still in practice and marijuana itself is just the same. I would like to see new studies done, however this is the most professional study i have seen or can find to date. I mean it's worth more to me to have concrete studies from 13 years ago, then to have some random claims made today.