In my opinion stress is the leading cause of acne, I experienced it when I never had acne in my life and I moved to a new school in a bad environment where I was stressed and getting in fights all the time.
Before that, I was the football star at my previous school and had many friends and never had acne.
Now again at the age of 23 I developed acne over a traumatic experience that caused a lot of stress and there you go again, I'm battling acne that I haven't had since the age of 18!
Guys I think are emotions and stress drive our acne more wild then all this diet, creams, etc.
We should work on meditating and trying not to OCD on our acne in order to improve it, it's harder said than done atleast for me but maybe for some you this could help. Just trying to help people out.