Unless you've become physically handicapped in this regard somehow (arthritis, etc.), this is usually a case of just being out of practice or short on patience, imo. Or playing on bad TVs, bad emulators, etc. I've seen too many Japanese Street Fighter champions still tearing it up in their 30s to think that it's a significant issue in and of itself.
I'm better at video games at 29 than I was when I was 9, and I don't think I was a slouch back then, either.