The only reports of marijuana's effect on stuttering have been largely anecdotal. The exceedingly few scientific studies are decades old (and very difficult to find). However, no one has specifically looked at specific strains of marijuana. If you're going to experiment you need to have some solid hypotheses in mind before hand and a way to measure the results. I do not give any credence to the anecdotal reports. These kind of reports are laden with the potential for confirmation bias (not to mention the fact that marijuana alters your perception, sensations, and memory. How can you trust your memories after the fact? Even assuming these strains reduce the THC you still have the problem of confirmation bias. I find myself wondering why your advisor has recommended you do this. If he thinks stuttering is related to cognition he's dead wrong. If he thinks that stuttering is caused by anxiety, again he's dead wrong. If he's getting at the fact that anxiety can exacerbate stuttering, he's correct. But there are legal ways to reduce anxiety. (And even in CO, WA and DC hospitals and clinics probably have regulations against working while on marijuana, regardless of it's affect). Anyway, go for it if you want, but tread carefully TL/DR: if you want to do it, go for it. But do yourself a couple favors: 1) formulate hypotheses and means to test those 2) recognize that you can be a great physician and stutter.