I see a reference (that I have NOT fully read) demonstrating a correlation between smoking behavior and ADHD, notwithstanding the original post for the article correlating secondhand smoke with ADHD. Anyone with any statistical background, or otherwise common knowledge, knows that correlation does not prove causation, which is a separate analysis.
However, when skimming the article by McClernon and Kollins, the emphasis clearly seems to be that the causation of high rates of smoking in individuals with ADHD is not yet well known but believed to involve several factors none of which reported to relate to ADHD symptom control of modification, in fact quite the opposite. The authors suggest that the reason people with ADHD smoke so much, has common disease mechanisms with the reasons they have ADHD, basically relating to thought patterns, planning, self control, lack of delayed gratification control, and they relate these in part to genetics.
From the authors' concluding statements:
These authors surely paint a different picture than nicotine being beneficial to ADHD so much as they suggesting that smoking cessation will improve ADHD symptoms.