I think the parent gave a good example of how it affected him long term. And I have to say the experience is mirrored with me. My attention span is not even 1/10th what it was when I started in this industry (where I had a team-office), and I don't think it would return very quickly if ever.

There could be other factors, for sure, but your brain is a muscle, if you do not exercise it (focus) then it will atrophy.