Nicotine is an extremely complex molecule which has been proven to have positive effects in the treatment of autism, as well as mild cognitive impairment, such as Alzheimer disease. Blanket statements like this are harmful to the general nature of science and show a disregard for empirical evidence.
Nicotine can be utilized for positive measures at therapeutic levels and was in Phase III clinical trials with the FDA for such uses before the backing pharmaceutical firm ran out of money. I recommend you do some research on Nicotine as a compound and interactions with nicotinic receptors in the body, the pharmacology is actually fascinating.
