How much of an effect does the nervous system have on OCD?

I feel like I'm inclined to abuse Vyvanse to reduce nervous system function. Even a day or two after I've taken it my OCD will be better while my ANS has decreased functioning. I've taken measurements of RMSSD which is a reliable indicator of parasympathetic activity, and I've found that after I take fish oil, a heavily research-backed supplement for reduction of stress which imprpves my RMSSD score, my OCD comes back.