Editing Nicotine (section)

===Central nervous system===
While acute/initial nicotine intake causes activation of neuronal nicotinic receptors, chronic low doses of nicotine use leads to desensitization of those receptors (due to the development of tolerance) and results in an antidepressant effect, with early research showing low dose nicotine patches could be an effective treatment of [[major depressive disorder]] in non-smokers.<ref name="pmid20965579">{{cite journal | vauthors = Mineur YS, Picciotto MR | title = Nicotine receptors and depression: revisiting and revising the cholinergic hypothesis | journal = Trends in Pharmacological Sciences | volume = 31 | issue = 12 | pages = 580–6 | date = December 2010 | pmid = 20965579 | pmc = 2991594 | doi = 10.1016/j.tips.2010.09.004 }}</ref>

Though tobacco smoking is associated with an increased risk of [[Alzheimer's disease]],<ref name="pmid19105840">{{cite journal | vauthors = Peters R, Poulter R, Warner J, Beckett N, Burch L, Bulpitt C | title = Smoking, dementia and cognitive decline in the elderly, a systematic review | journal = BMC Geriatrics | volume = 8 | page = 36 | date = December 2008 | pmid = 19105840 | pmc = 2642819 | doi = 10.1186/1471-2318-8-36 | doi-access = free }}</ref> there is evidence that nicotine itself has the potential to prevent and treat Alzheimer's disease.<ref name=pmid19184661>{{cite book |vauthors=Henningfield JE, Zeller M |volume=192 |issue=192 |pages=511–34 |year=2009 |pmid=19184661 |doi=10.1007/978-3-540-69248-5_18 |isbn=978-3-540-69246-1 |series=Handbook of Experimental Pharmacology |title=Nicotine Psychopharmacology |chapter=Nicotine Psychopharmacology: Policy and Regulatory }}</ref>

Smoking is associated with a decreased risk of [[Parkinson's disease]]; however, it is unknown whether this is due to people with healthier brain dopaminergic reward centers (the area of the brain affected by Parkinson's) being more likely to enjoy smoking and thus pick up the habit, nicotine directly acting as a [[Neuroprotection|neuroprotective agent]], or other compounds in cigarette smoke acting as neuroprotective agents.<ref>{{cite journal | vauthors = Quik M, O'Leary K, Tanner CM | title = Nicotine and Parkinson's disease: implications for therapy | journal = Movement Disorders | volume = 23 | issue = 12 | pages = 1641–52 | date = September 2008 | pmid = 18683238 | pmc = 4430096 | doi = 10.1002/mds.21900 }}</ref>

Nicotine may partly attenuate [[sensory gating]] and attentional deficits associated with [[schizophrenia]]. Short-term use of [[transdermal]] nicotine was found to improve subjects’ reaction time and [[Vigilance (psychology)|alertness]] in given tasks. Nicotine was not found to improve [[Negative symptoms of schizophrenia|negative]], [[Psychosis|positive]], or other cognitive symptoms of schizophrenia.<ref>{{cite journal |vauthors=Harris JG, Kongs S, Allensworth D, Martin L, Tregellas J, Sullivan B, Zerbe G, Freedman R |date=July 2004 |title=Effects of nicotine on cognitive deficits in schizophrenia |journal=Neuropsychopharmacology |volume=29 |issue=7 |pages=1378–1385 |doi=10.1038/sj.npp.1300450 |pmid=15138435}}</ref>