Anxiety falls under neurological I believe. Honestly if you're first time taking or doing anything, don't do it for the test. You don't know how your body will react to it. Personally, I say don't take it. The test is grading your ability to comprehend and communicate ideas. Sure you have a stutter so it's a little harder, but that shouldn't effect your overall ability to complete those tasks. Before the test starts, explain that you have a stutter, they should understand.