Yes there presumably is. If you want scientific research, you should go to scholar.google.com or better yet to the library of your nearest teaching hospital / medical university. There have been thousands if not tens of thousands papers on the issue. You'll never get a scientifically valid answer on the internet, and probably not even in the library - but at least there you'll have data.

Anecdote time: I know a doctor who is convinced that he is right on his opinion that marijuana causes depression, has near-100% gateway properties and causes long term brain damage even after short periods of use. The rub? He works at a psychological hospital that get a lot of patients with acute drug-induced psychoses or other drug-related issues. From his sample, of course he comes to his conclusions! I have tried to explain the concept of 'sample bias' several times to him but either he is incapable of such numeric thinking or just refuses to do so.