http://www.world-science.net/exclusives/061125_marijuana.htm

For scientists, as for so­ci­e­ty at large, ma­ri­jua­na has been among the most be­dev­il­ing of drugs.

Some stud­ies have found that the il­lic­it sub­stance dam­ag­es the mem­o­ry. Oth­ers sug­gest that it does­n’t, or even that it’s ben­e­fi­cial for some con­di­tions, in­clud­ing Alz­hei­mer’s dis­ease. Through it all, the pub­lic clam­ors for an­swer­s—des­per­ate­ly needed to re­solve a decades-long, rau­cous de­bate over wheth­er pot is safe enough to be le­gal.

Leaves of the ma­ri­jua­na or Can­na­bis sa­ti­va plant (cour­te­sy Io­wa Dept. of Pub­lic Safe­ty)

A theory now emerg­ing from a re­search group pro­poses that the truth may be more com­plex than ei­ther side in that de­bate would have us be­lieve. Ma­ri­jua­na may have played a trick on us all, they sug­gest, by play­ing the roles of both health vil­lain and he­ro...