Actually, I have an entire blog loaded with information on the benefits of nicotine. The most pertinent posts might be these two, but do feel free to read them all:
The Truth About Nicotine: Pay Attention
The Truth About Nicotine: Targeting Nicotinic Receptors and Profits
Here is a brief synopsis:
Attention Deficit Disorder - Your choice, treat with nicotine (which is what I do) or with methylphenidate, a toxic, addictive drug that is so controlled that your doctor must hand-write you each new prescription and you must present ID when you pick it up.
Dementia - Nicotine prevents the build-up of plaques, tangles, and alpha-synuclean proteins. The first two cause Alzheimers and the latter causes Parkinson's. The Parkinsonian type of dementia (also called Lewy Body Disease or LBD) is characterized by hallucinations, delusions, and progressive immobility. Nicotine is the only substance I have ever heard of that can prevent the junk that causes dementia from clogging up the brain. Since my mother has LBD and there is a genetic element, guess who won't be giving up nicotine until you pry it from her cold dead fingers. (Right, me.)
Memory - Improves visual memory and spatial working memory. Are there any other treatments for that? Hmmm.
Depression - Actually, this is where my study of nicotine first began. About 20 years ago, psychiatrists treating patients for smoking addiction noticed that their patients symptoms of depression became much worse when they were abstinent. In one case, a patient told her doctor, "If you let me smoke, I'll stop trying to kill myself." Here's an interesting article:
Nicotine Addiction and Other Psychiatric Disorders - Psychiatric Times
Treatment of depression is tricky. Antidepressants work for only 30% of patients and many have pretty nasty side effects (seizures, tardive dyskenesia, etc.). Some patients need nicotine added to their medication to reach normal functioning. Some patients can get by without medication as long as they have nicotine.
Anxiety - Would you prefer nicotine or Valium? Research Valium before you answer the question.
Schizophrenia - Nicotine helps to reduce impairments caused by meds used to treat this disorder.
Stress Relief - Nicotine relaxes the skeletal muscles without impairing attention. Most stress-relieving substances relax people to the point of going to sleep. Sometimes that's not what you want or need.
BTW: These beneficial effects are seen on lab animals and on humans who have never used nicotine. So the effects are not, as many people believe, only relief of withdrawal symptoms.