Nicotine

Nicotine is also used in the treatment of attention deficit hyperactivity disorder (ADHD).

An excerpt from the article 15 facts about nicotine

The therapy uses patches containing nicotine, which is perfectly absorbed through the skin. Just 45 minutes after applying a patch containing 7 mg of nicotine, the patients examined by the researchers had better control over impulsive behavior and better remembered the images shown to them.