To be honest, this topic is completely foreign to me since I love math and have never experienced any math anxiety in my life! I am also not an expert on the current literature, but I thought this article might be useful for students:
Apparently, overcoming math anxiety is all about controlling your emotions. Of course, don’t underestimate good preparation as one important way to reduce anxiety about taking a math test. But this article also suggests that calming yourself down and focusing on what needs to be done, and thinking about successes you’ve had in the past, among other things, can also help. Easier said than done, I’m sure.
A related article talks about the differences in how confident students and anxious students deal with stress and how that affects school performance:
I wonder whether the skill of overcoming performance anxiety in some other context is transferable to math? In other words, would being a dancer, musician or sports player improve one’s ability to overcome math anxiety? I suspect yes.