Yes, exactly.
I had an exceptionally colicky baby, who had terrible problems going to and staying asleep. We were very attached, and she was held pretty much non-stop. But at one point, we had to do CIO, or I was going to end up committed. It took 3 days (using Ferber's techniques) and her sleep problems (and mine) were cured. There is just no way that that is comparable to a chronically non-nurturing experience.
I do believe that chronic neglect leads to changes in the brain and long-term damage. But not a couple days of CIO.
The article posted by the OP links to this one, which states
This really angers me. If they don't understand the difference between correlation and causation they shouldn't be doing research.
It is much more likely that kids who have ADHD are much more likely to have persistent crying episodes, poor school performance, and antisocial behavior. It's genetic! Although I also recognize that neglect and poor parenting can cause similar issues.