"While nicotine is highly addictive, researchers have also shown the drug to enhance learning and memory—a property that has launched efforts to develop nicotine-like drugs to treat cognitive deficits in Alzheimer’s and Parkinson’s diseases, schizophrenia, and attention-deficit/hyperactivity disorder."
Mechanism of nicotine's learning effects explored
(Oops! I was gonna editorialize some more but I just hacked a big oyster on my keyboard.)
UPDATE: And then what to my wondering eyes should appear but a post by Laura Knight-Jadczyk on her blog "Postcards from the Edge of Reality...", entitled Let's All Light Up!, wherein she writes: "Nicotine DOUBLES the efficiency of our thinking. Hmmm... I think that makes it pretty clear why the PTB (Powers That Be) wish to stamp out smoking."
"Don't Bogart that joint my friend..."