What everyone needs to understand about anxiety and panic attacks is that you can STOP them as soon as you notice them coming on. Don't lead yourself to believe that you're having a panic attack and it is inevitable because of the marijuana. All marijuana will do is make you feel a little differently, something as subtle as a tingle in your head can cause an anxious prone person to fear of a brain tumor, which then can spark an attack. I highly suggest that the first thing you do (you being people prone to anxiety/panic attacks) is erase the notion from your mind that it's definite once it starts in. Secondly practice breathing properly when you notice it happening. Thirdly and quickly after you control your breathing--deny the attack mentally and move on with whatever you were doing. I don't recommend purposely thinking about something else in attempt to forget about the attack, because it won't work. You'll then just end up in a situation where you're putting far too much energy into something that doesn't deserve the time of day, making it a bigger deal, and more likely to take control of you. You can stay in control though, by just denying the attack..it sounds simple but trust me it works. After you take a few controlled and propper breathes simply continue doing whatever you were doing, without letting yourself believe anything is really wrong with you..and before you know it you'll be back doing what you were doing, panic free and slightly better at controlling your attacks..and eventually after you've handled it well enough, you won't get anymore attacks because you won't freak yourself out about little harmless feelings...

Hopefully this helps someone..