Nicotine

A Comprehensive Research Review of Pharmacology, Cognitive Effects, Neuroprotective Properties, and Lifespan Considerations Nicotine is the primary psychoactive constituent found in tobacco products and has been the subject of extensive scientific investigation spanning decades. While smoking remains the leading cause of preventable death in the United States and throughout the developed world, the pharmacological properties of nicotine itself—distinct from the thousands of harmful combustion byproducts found in cigarette smoke—have emerged as a subject of considerable research interest. It is critically important to distinguish between the molecule nicotine and the delivery system of combustible tobacco: nicotine does not cause cancer. Rather, it is the tar, carbon monoxide, and thousands of other chemicals generated during tobacco combustion that make smokers susceptible to cancer, heart disease, and respiratory illness. Nicotine binds to nicotinic acetylcholine receptors (nAChRs), which are pentameric ligand-gated ion channels composed of various combinations of alpha and beta subunits (α1–7, 9–10; β1–4). These receptors are widely distributed throughout the human brain and peripheral nervous system and play essential roles in neuromuscular junction function, neurotransmitter release, brain maturation, reward processing, and cognition. The effects of nicotine are highly dependent on the timing and context of exposure, the dose administered, the age and developmental stage of the individual, and the specific nAChR subtypes that are engaged. Contemporary research has revealed a remarkably nuanced pharmacological profile for nicotine. On one hand, both preclinical models and human studies have demonstrated that nicotine possesses cognitive-enhancing properties, with attention, working memory, fine motor skills, and episodic memory being particularly sensitive to its effects. On the other hand, nicotine exposure during critical developmental periods—particularly the prenatal period and adolescence—can produce neurotoxic effects that disrupt brain programming, alter reward circuitry, and increase vulnerability to addiction and mood disorders. In adults and aging populations, nicotine has shown potential neuroprotective effects that are being actively investigated in the context of neurodegenerative diseases such as Alzheimer’s disease and Parkinson’s disease. This comprehensive review synthesizes evidence from peer-reviewed research, including the systematic review by Ren, Lotfipour, and Leslie (2022) published in Pharmacology, Biochemistry and Behavior, and the selective review by Valentine and Sofuoglu (2018) published in Current Neuropharmacology, alongside additional recent research findings. This article aims to provide an evidence-based educational reference covering nicotine’s mechanisms of action, its effects throughout the lifespan, dosing considerations for nicotine replacement therapy, and the current scientific landscape surrounding its risks and potential therapeutic applications.

How It Works Nicotinic Acetylcholine Receptors (nAChRs) Nicotine’s primary sites of action are the nicotinic acetylcholine receptors (nAChRs), which are ligand-gated ion channels consisting of pentameric combinations of nine alpha subunits (α2–α10) and three beta subunits (β2–β4) arranged around a central pore permeable to sodium, potassium, and calcium ions. The majority of neuronal nAChRs in the central nervous system are excitatory and fast-acting (operating in the millisecond range), and are predominantly located presynaptically, where they modulate the release of key neurotransmitters including acetylcholine, dopamine, serotonin, glutamate, GABA, and norepinephrine. nAChRs can be assembled as either homomeric receptors formed by a group of identical alpha subunits (such as the α7 subtype) or heteromeric receptors formed by combinations of alpha and beta subunits (such as α4β2 or α3β4). The two most prominent nAChR subtypes in the brain are the α4β2 and α7 receptors, which are critical to both the reinforcing and cognitive-enhancing effects of nicotine.

Activation, Desensitization, and Upregulation

Nicotine can both activate and desensitize nAChRs that normally mediate the physiological effects of acetylcholine. Following its release into the synapse, acetylcholine is rapidly inactivated within milliseconds by the enzyme acetylcholinesterase. In contrast, nicotine is not a substrate for this enzyme and therefore causes prolonged activation of nAChRs upon receptor binding. With repeated nicotine exposure, nAChRs become desensitized, diminishing nicotine’s effects, and this desensitization leads to an upregulation of nAChR density. The sensitivity to desensitization varies across receptor subtypes. The nAChR subtypes controlling glutamate release (primarily the α7 subtype) desensitize more slowly than those controlling GABA release (mainly non-α7 subtypes). This differential desensitization may result in greater glutamate release relative to GABA release following prolonged nicotine exposure, which can lead to enhanced dopamine release in the nucleus accumbens—an important mechanism implicated in nicotine’s reinforcing properties. Nicotine exhibits what researchers describe as an “inverted J dose-response,” where low doses or brief exposures improve cognitive function, while higher doses or prolonged exposure either do not improve or may impair cognitive performance.

Bivalent Model of Nicotine Reinforcement

Research supports a bivalent model of nicotine reinforcement driven by both positive and negative reinforcement pathways through nicotine’s actions on α4β2 and α7 nAChRs. Nicotine’s cognitive effects in the prefrontal cortex provide negative reinforcement (relieving cognitive deficits and

other symptoms associated with nicotine withdrawal), while its effects on reward circuitry in the nucleus accumbens provide positive reinforcement through enhanced dopamine release. The activation of nAChRs on ventral tegmental area (VTA) dopamine cell bodies and presynaptic terminals in both the nucleus accumbens and prefrontal cortex contribute to these dual effects.

Developmental Regulation of nAChR Function

A critical aspect of nicotine’s pharmacology is the developmental regulation of nAChR function throughout the lifespan. The expression patterns and pharmacological properties of nAChRs shift significantly from gestation through adulthood, with differing modulation of neurotransmitter release at each stage. Age-dependent changes in nAChR pharmacology are particularly important in the development of the cerebellum and sensory cortices, as well as in dopamine release from the ventral midbrain and norepinephrine release from the hippocampus. This dynamic expression of the cholinergic system means that nicotine exposure produces fundamentally different effects depending on the developmental period in which exposure occurs.

Research Benefits Cognitive Enhancement A large and growing body of evidence supports nicotine’s cognitive-enhancing properties. A landmark meta-analysis by Heishman et al. of 41 placebo-controlled studies that included nicotine administration to non-smokers or satiated smokers found that nicotine had significant positive effects on fine motor performance, short-term episodic memory, and working memory. Additionally, “alerting attention” (maintenance of an alert state) and “orienting attention” (directing attention to sensory events) were positively impacted. Nicotine use in adults positively influences learning, memory, and attention, and improves mood, stress regulation, and anxiety. Research has also shown that nicotine’s cognitive-enhancing effects may contribute to moodstabilizing effects by improving attentional focus and shifting attentional bias away from negative stimuli. This is particularly relevant in populations with underlying cognitive deficits, where the cognitive-enhancing properties of nicotine may represent a form of self-medication.

Neuroprotection in Aging and Neurodegenerative Disease

Clinical and preclinical data support a neuroprotective effect of nicotine during adulthood and senescence, with potential to prevent or delay the onset of degenerative neurological disorders such as Alzheimer’s disease and Parkinson’s disease. Alzheimer’s disease is characterized by aggregation and precipitation of amyloid precursor proteins (APP) in the form of plaques, which result from overproduction and/or altered metabolism of APP-β. Alpha-7-containing nAChRs are

present in these plaques, and research has shown that nicotine prevents the conversion of APP-α to APP-β and lowers the secretion of APP-β. The proposed mechanism involves a central role of α4β2 and α7 nAChRs in enhancing the release of neuroprotective APP-α and lowering APP-β production. A U.S. government-funded veteran’s study found that smoking reduced Parkinson’s disease mortality by 64%. Nicotine has been shown to promote neuron survival and partially protect against Parkinson’s disease by suppressing SIRT6 in mice, increasing AKT signaling, and reducing the secretion of TNF-alpha. The neuroprotective effects of nicotine have been observed particularly in the hippocampus, entorhinal cortex, and neocortex. A 2023 study published in Nature Communications by Yang et al. demonstrated that low-dose nicotine administration significantly restored NAMPT activity and NAD+ levels in the brain, heart, and muscle tissues of middle-aged mice, ameliorating anxiety and cognitive deficits associated with aging. These findings suggest that nicotine may rebalance NAD+ homeostasis and improve aging-related symptoms by enhancing NAMPT activity, providing a novel mechanistic basis for nicotine’s neuroprotective properties.

Mild Cognitive Impairment (MCI)

The MIND Study (Memory Improvement through Nicotine Dosing) is specifically studying the potential benefits of nicotine to test whether it can improve or alleviate symptoms of memory loss in people with mild cognitive impairment and possibly delay or prevent progression to Alzheimer’s disease. In an earlier pilot clinical trial, 74 nonsmoking adults diagnosed with MCI were prescribed nicotine or placebo patches for six months. Those using the nicotine patch showed improvement in attention and memory, with no serious side effects or signs of withdrawal. Importantly, there was no evidence of abuse liability with transdermal nicotine in this nonsmoking population.

Psychiatric and Neurological Applications Under Investigation

Research is also exploring the potential of nicotinic receptor modulation in several additional clinical contexts. Attention-deficit/hyperactivity disorder (ADHD) is associated with cognitive deficits in attention, working memory, and impulse control—domains that are particularly sensitive to nicotine’s effects. Nicotine has shown promise in reducing depressive symptoms and improving mood regulation, likely through its modulation of dopaminergic and serotonergic neurotransmission. Ongoing preclinical studies are examining nicotine’s potential roles in certain cancers (sarcoma) and inflammatory conditions through nAChR-mediated anti-inflammatory pathways.

Anti-Inflammatory Properties

Nicotine has been shown to have neuroinflammatory effects in adolescence that switch to neuroprotection in adulthood, suggesting that neuronal nAChRs may serve as novel targets for inflammation and neuroprotection in adults. Research on the “cholinergic anti-inflammatory pathway” has demonstrated that nicotine can reduce abundance and secretion of TNF-alpha in a SIRT6-dependent manner, supporting a role for nicotinic agonism in modulating inflammatory responses in the central nervous system.

What the Science Shows Cognitive Enhancement Studies Heishman et al. (2010) conducted a comprehensive meta-analysis of 41 placebo-controlled studies examining nicotine’s effects in non-smokers and satiated smokers. The analysis confirmed significant positive effects on fine motor performance, short-term episodic memory, working memory, alerting attention, and orienting attention. These effects were independent of withdrawal reversal, establishing that nicotine has genuine cognitive-enhancing properties beyond simply reversing abstinence-related deficits. Valentine and Sofuoglu (2018) reviewed extensive evidence demonstrating that attention, working memory, fine motor skills, and episodic memory are particularly sensitive to nicotine’s effects, and that the α4, β2, and α7 nAChR subunits participate in these cognitive-enhancing effects. Neuroimaging studies using fMRI have confirmed that nicotine increases activity in executive control regions (anterior cingulate cortex, frontoparietal cortices, thalamus) while reducing activity in default-mode network regions, consistent with enhanced cognitive processing. A population-based study of 2,163 participants demonstrated that smokers had deficits in attention, working memory, and impulse control, though the severity of deficits was not correlated with duration of tobacco use. Smokers with even low amounts of lifetime exposure displayed these deficits, suggesting that individuals with pre-existing cognitive deficits may be predisposed to developing tobacco use disorder—and may derive particular benefit from nicotine’s cognitive effects.

Neuroprotection and Aging Studies

Gutala et al. (2006) and Utsuki et al. (2002) demonstrated in preclinical models that nicotine treatment enhances expression of APP and APLP2 proteins, prevents the conversion of APP-α to APP-β, and lowers the secretion of APP-β. Mousavi and Hellström-Lindahl (2009) confirmed that nicotine-induced attenuation of β-amyloidosis is mediated by nAChRs and not by a direct effect of nicotine itself.

Nicholatos et al. (2018) demonstrated that nicotine promotes neuron survival and partially protects against Parkinson’s disease by suppressing SIRT6, which increases AKT signaling and reduces TNF-alpha secretion. These mechanisms likely mediate the impact of SIRT6 on dopamine neuron survival and Parkinson’s disease pathology. Yang et al. (2023) showed in Nature Communications that low-dose nicotine (2 µg/mL in drinking water) administered from 6 to 12 months in mice significantly restored NAMPT activity and NAD+ levels in brain, heart, and muscle tissues, while high-dose nicotine had a negative effect on NAMPT activity and NAD+ levels, reinforcing the dose-dependent nature of nicotine’s effects. Newhouse et al. (2012) conducted a 6-month double-blind pilot clinical trial of transdermal nicotine in 74 nonsmoking adults with mild cognitive impairment. Participants receiving nicotine patches showed significant improvements in attention and memory compared to placebo, with no serious adverse effects and no evidence of abuse liability or withdrawal symptoms upon cessation.

Developmental Exposure Studies

Ren, Lotfipour, and Leslie (2022) conducted a comprehensive systematic review of 156 references examining the effects of nicotine exposure across the lifespan. Key findings from developmental studies include the following: prenatal nicotine exposure (3 mg/kg/day in Sprague-Dawley rats during gestational days 4–18) increased cocaine self-administration and locomotor activity in offspring, with molecular mechanisms involving increased c-fos mRNA expression in the nucleus accumbens and altered corticolimbic dopamine system development. Adolescent nicotine exposure (60 µg/kg i.v. over 4 days in Sprague-Dawley rats during postnatal days 28–31) increased self-administration of multiple drugs of abuse (nicotine, cocaine, methamphetamine, ethanol, and fentanyl) through D2 receptor and microglia activation. Counotte et al. (2009, 2011) demonstrated that adolescent nicotine exposure (0.4 mg/kg s.c., 3 times daily for 10 days) produced lasting attention deficits in adulthood, mediated by reduced mGluR2 protein and function on presynaptic terminals of prefrontal cortex glutamatergic synapses.

Dosing Protocol

Important Disclaimer: Nicotine is an addictive substance. The following dosing information is provided for educational purposes only and relates to FDA-approved nicotine replacement therapy (NRT) products used for smoking cessation. Nicotine products should only be used under the guidance of a qualified healthcare provider. This information is not intended to encourage the use of nicotine by non-smokers or for any unapproved indication.

Transdermal Nicotine Patch (Standard Smoking Cessation Protocol)

The nicotine transdermal patch is the most commonly used form of NRT and is regarded as one of the simplest options, often leading to better patient compliance. Patches are available in three standard dosage strengths: 21 mg, 14 mg, and 7 mg, which are applied once daily. The selection of the initial dose is based on the individual’s daily cigarette consumption. For individuals smoking more than 10 cigarettes per day: Step 1 involves the 21 mg patch for 4 weeks, followed by Step 2 with the 14 mg patch for 2 weeks, and Step 3 with the 7 mg patch for 2 weeks (total treatment duration of 8 weeks). For individuals smoking 10 or fewer cigarettes per day: Step 1 involves the 14 mg patch for 6 weeks, followed by Step 2 with the 7 mg patch for 2 weeks (total treatment duration of 8 weeks). Patches should be applied to a clean, dry, hairless area of the upper body or arm. They should be firmly pressed onto the skin for 10 seconds to ensure proper adhesion and should be applied to a new location each day. Some patches are designed to be worn for 24 hours, while others are designed for 16 hours of use. Patients who experience vivid dreams may remove the patch at bedtime and apply a new one in the morning.

Other NRT Delivery Methods

Nicotine is also available as gum (2 mg and 4 mg), lozenges (2 mg and 4 mg), nasal spray (approximately 0.5 mg per spray), and oral inhalers. Each form has its own dosing protocol based on smoking history and individual response. Multiple forms of NRT can be used simultaneously (such as a patch combined with gum) under healthcare provider supervision to optimize treatment outcomes.

Research Dosing for Cognitive Studies

In the MIND Study pilot trial for mild cognitive impairment, transdermal nicotine patches were used at escalating doses up to 15 mg/day over a 6-month treatment period in nonsmoking adults aged 55 and older. Research dosing protocols for investigational uses differ from standard smoking cessation protocols and are conducted under strict medical supervision with regular monitoring.

Side Effects Common Side Effects of Nicotine Replacement Therapy The most commonly reported side effects of transdermal nicotine include skin irritation, redness, or itching at the patch application site; vivid or unusual dreams (particularly with 24-hour patches); headache; dizziness; nausea; and insomnia or sleep disturbances. These side effects are generally mild and often diminish with continued use.

Signs of Nicotine Excess

Symptoms of excessive nicotine intake include nausea, vomiting, dizziness, weakness, rapid heartbeat, increased blood pressure, sweating, salivation, abdominal pain, and diarrhea. These symptoms typically resolve upon dose reduction or removal of the nicotine source.

Cardiovascular Effects

Nicotine can increase heart rate and blood pressure. Individuals with heart disease, recent heart attack, irregular heartbeat, or uncontrolled high blood pressure should use NRT with caution and under medical supervision. While NRT carries some cardiovascular risk, these risks are substantially lower than those associated with continued smoking.

Age-Dependent Adverse Effects

The adverse effects of nicotine are profoundly age-dependent. Prenatal exposure is associated with reduced pulmonary function, auditory processing defects, impaired cardiorespiratory function, lower birth weight, increased risk of preterm delivery, cleft palate, and sudden infant death syndrome. Gestational nicotine exposure also impacts brain development at doses that do not delay general growth, producing motor, sensory, cognitive, and behavioral deficits. Adolescent nicotine exposure enhances susceptibility to addiction, impairs attention and working memory, produces depression-like and anxiety-like behaviors, and increases vulnerability to subsequent drug abuse. In contrast, adult nicotine use, while associated with addiction risk, does not produce the neurodevelopmental harm seen in younger populations.

Withdrawal Symptoms

Abruptly discontinuing nicotine after regular use can trigger withdrawal symptoms including difficulty concentrating, impaired attention, impaired working memory, irritability, anxiety, depressed mood, increased appetite and weight gain, restlessness, insomnia, and strong cravings. These symptoms typically peak within the first week and gradually subside over 2–4 weeks.

Contraindications and Precautions

Nicotine replacement therapy is contraindicated or should be used with extreme caution in several populations and clinical scenarios. Pregnant women should not use nicotine products, as nicotine readily crosses the placental barrier and is found in amniotic fluid and the umbilical cord, causing significant harm to fetal development. Breastfeeding mothers should use caution, as nicotine and its metabolite cotinine pass into breast milk and can affect infant development. Individuals under 18 years of age should not use NRT products without direct medical supervision, given the heightened vulnerability of the developing adolescent brain to nicotine’s effects on reward circuitry, attention, and mood regulation.

Additional precautions apply to individuals with cardiovascular disease (including recent myocardial infarction, unstable angina, serious cardiac arrhythmias, or vasospastic conditions), uncontrolled hypertension, active peptic ulcer disease, allergy to adhesive tape or skin conditions that may worsen with patch application, and individuals taking prescription medications for depression or asthma, as nicotine may alter the metabolism or effects of these medications. It is critical to note that research clearly demonstrates nicotine has neuroinflammatory effects during adolescence that switch to neuroprotection in adulthood, establishing a strong contraindication for nicotine use at younger ages.

Comparison: Nicotine Delivery Methods

Research has clearly established that while nicotine itself carries certain health risks (primarily addiction potential and cardiovascular effects), the delivery method dramatically influences the overall risk profile. Replacing traditional combustible cigarettes with alternative nicotine delivery systems reduces exposure to tobacco’s carcinogens and is substantially less harmful than smoking. However, each delivery method carries its own risk-benefit profile. Combustible cigarettes deliver nicotine rapidly to the brain within 10–20 seconds of inhalation, which contributes to the strong reinforcing properties and high addiction potential. However, cigarette smoke contains over 7,000 chemicals, including at least 70 known carcinogens, making smoking the most harmful delivery method by far. E-cigarettes (vaping) reduce exposure to carcinogens but carry health risks including addiction, metal exposure, inhalation of toxic solvents, and vaping-associated lung injury. Clinical data suggest that many smokers who switch to vaping maintain their habit rather than quitting entirely and may increase total daily nicotine use. Nicotine replacement therapy (patches, gum, lozenges, inhalers, nasal sprays) provides controlled, predictable doses of nicotine without exposure to combustion byproducts. Transdermal patches provide the most gradual and sustained delivery, which is least likely to produce the sharp spikes in brain nicotine levels associated with high addiction potential. Nicotine pouches and other newer oral products offer smoke-free, vapor-free delivery options. Pure nicotine administration in research settings (via injection, nasal spray, or transdermal patch) remains the gold standard for studying the pharmacological effects of nicotine independent of other tobacco constituents.

Success Tips

For individuals using nicotine replacement therapy for smoking cessation, evidence-based strategies for maximizing treatment success include the following considerations. Complete the full recommended treatment course, as premature discontinuation is the most common reason for NRT failure. Use NRT in conjunction with a behavioral support program, as combination

approaches have significantly higher success rates than either approach alone. Consider combination NRT (such as a patch plus gum or lozenges) under healthcare provider guidance, as research supports the superiority of combination approaches over single-product NRT. Begin NRT on or before the designated quit date, and do not stop using NRT if a slip or relapse occurs— continue using the product and keep trying to quit. For researchers and clinicians interested in nicotine’s cognitive and neuroprotective effects, it is important to note that nicotine’s cognitive-enhancing effects appear to be most pronounced in individuals with underlying cognitive deficits, including those with psychiatric disorders such as schizophrenia, ADHD, major depression, and PTSD. For healthy nonsmokers with no underlying cognitive difficulties, nicotine offers minimal cognitive improvement. Poor cognitive performance at baseline predicts relapse among smokers attempting to quit, suggesting that cognitiveenhancement strategies may improve smoking cessation outcomes, particularly in vulnerable populations.

Storage and Handling

Nicotine replacement products should be stored at room temperature, generally between 68°F and 77°F (20°C–25°C), in a dry location away from direct sunlight and heat sources. Patches should remain in their sealed pouch until immediately before use, as exposure to air can reduce efficacy. Used patches should be disposed of carefully by folding the sticky sides together, placing them back in the original pouch, and discarding them in a manner that prevents access by children and pets. Used patches retain enough nicotine to cause poisoning if ingested by a child or animal. All NRT products should be kept out of the reach of children at all times. Patients should wash their hands thoroughly after applying or removing patches to avoid inadvertent nicotine transfer.

Legal Status

In the United States, nicotine replacement therapy products (patches, gum, lozenges) are available over the counter without a prescription for individuals aged 18 and older. Nicotine inhalers and nasal sprays are available by prescription only. E-cigarettes and vaping products containing nicotine are regulated by the FDA’s Center for Tobacco Products. Pure nicotine is a controlled substance in research settings and is subject to institutional and regulatory oversight when used in clinical trials. Nicotine products are not approved for sale to individuals under 18 years of age. State and local regulations may impose additional restrictions on the purchase, sale, and use of nicotine-containing products. Research use of nicotine for off-label indications (such as cognitive enhancement or neuroprotection) is conducted under Institutional Review Board approval and FDA oversight as appropriate.

Frequently Asked Questions Does nicotine cause cancer? No. Nicotine itself is not classified as a carcinogen. It is the tar and thousands of other chemicals found in combustible tobacco smoke that cause cancer, heart disease, and respiratory illness. While nicotine is the addictive component of tobacco, the cancer risk is attributable to the delivery method (combustion), not to the nicotine molecule. Can nicotine improve memory and cognitive function? Research supports that nicotine has cognitive-enhancing effects, particularly in the domains of attention, working memory, fine motor skills, and episodic memory. These effects are most pronounced in individuals with underlying cognitive deficits. Clinical trials have demonstrated improvements in attention and memory in nonsmoking adults with mild cognitive impairment using transdermal nicotine patches. However, these findings are still being validated in larger trials. Is nicotine neuroprotective against Alzheimer’s and Parkinson’s disease? Preclinical and epidemiological data strongly suggest neuroprotective effects. Nicotine prevents the formation of pathological amyloid-beta plaques associated with Alzheimer’s disease and promotes dopaminergic neuron survival through SIRT6 suppression in Parkinson’s disease models. A large veteran’s study found that smoking reduced Parkinson’s mortality by 64%. However, the risks of tobacco smoking far outweigh these benefits, and research is focused on developing safer nicotinic receptor agonists for therapeutic use. Is nicotine safe during pregnancy or adolescence? No. Nicotine is contraindicated during pregnancy, as it crosses the placental barrier and causes significant harm to fetal development, including reduced birth weight, preterm delivery, and increased risk of sudden infant death syndrome. Adolescent nicotine exposure is similarly concerning, as it enhances susceptibility to addiction, impairs attention and memory, and produces lasting changes in mood regulation and reward circuitry. Can nicotine replacement therapy be used long-term? While the standard NRT course is 8–10 weeks, some individuals may benefit from longer treatment. Clinicians should weigh the risks of continued NRT use against the far greater risks of returning to smoking. There are no significant safety concerns associated with using multiple NRT products simultaneously, and long-term NRT use is considered substantially safer than continued tobacco use.

Does nicotine affect different age groups differently?

Yes. Nicotine’s effects are profoundly age-dependent due to the dynamic expression of nAChRs throughout the lifespan. Prenatal and early postnatal exposure disrupts brain development. Adolescent exposure enhances addiction vulnerability and impairs cognition. Adult exposure carries addiction risk but also demonstrates cognitive-enhancing and potentially neuroprotective properties. In aging populations, nicotine’s neuroprotective effects are most prominent, including enhancement of NAD+ homeostasis and reduction of neuroinflammation. What receptor subtypes are most important for nicotine’s cognitive effects? The α4β2 and α7 nAChR subtypes are the most strongly implicated. The α7 subtype is especially dense in the hippocampus and prefrontal cortex and modulates sensory gating, attention, and memory. The β2-containing receptors mediate attention, working memory, inhibitory control, and behavioral flexibility. Selective α7 nAChR agonists are currently being developed as potential cognitive-enhancing therapeutics for schizophrenia, Alzheimer’s disease, and ADHD.

References

1. Ren M, Lotfipour S, Leslie F. Unique effects of nicotine across the lifespan. Pharmacology, Biochemistry and Behavior. 2022;214:173343. 2. Valentine G, Sofuoglu M. Cognitive effects of nicotine: Recent progress. Current Neuropharmacology. 2018;16(4):403-414. 3. Heishman SJ, Kleykamp BA, Singleton EG. Meta-analysis of the acute effects of nicotine and smoking on human performance. Psychopharmacology. 2010;210(4):453-469. 4. Newhouse PA, Potter A, Dumas J, Thiel CM. Functional brain imaging of nicotinic effects on higher cognitive processes. Biochem Pharmacol. 2011;82(8):943-951. 5. Newhouse P, Kellar K, Aisen P, et al. Nicotine treatment of mild cognitive impairment: A 6month double-blind pilot clinical trial. Neurology. 2012;78(2):91-101. 6. Gutala R, Wang J, Hwang YY, Haq R, Li MD. Nicotine modulates expression of amyloid precursor protein and amyloid precursor-like protein 2 in mouse brain and in SH-SY5Y neuroblastoma cells. Brain Res. 2006;1093:12-19. 7. Utsuki T, Shoaib M, Holloway HW, et al. Nicotine lowers the secretion of the Alzheimer’s amyloid β-protein precursor that contains amyloid β-peptide in rat. J Alzheimers Dis. 2002;4:405415.

8. Mousavi M, Hellström-Lindahl E. Nicotinic receptor agonists and antagonists increase sAPPα secretion and decrease Aβ levels in vitro. Neurochem Int. 2009;54:237-244. 9. Nicholatos JW, Francisco AB, Bender CA, et al. Nicotine promotes neuron survival and partially protects from Parkinson’s disease by suppressing SIRT6. Acta Neuropathol Commun. 2018;6:120. 10. Yang L, Shen J, Liu C, et al. Nicotine rebalances NAD+ homeostasis and improves agingrelated symptoms in male mice by enhancing NAMPT activity. Nat Commun. 2023;14(1):900. 11. Dorn HF. Tobacco consumption and mortality from cancer and other diseases. Public Health Rep. 1959;74:581-593. 12. Ferrea S, Winterer G. Neuroprotective and neurotoxic effects of nicotine. Pharmacopsychiatry. 2009;42:255-265. 13. Franke RM, Park M, Belluzzi JD, Leslie FM. Prenatal nicotine exposure changes natural and drug-induced reinforcement in adolescent male rats. Eur J Neurosci. 2008;27:2952-2961. 14. Dwyer JB, Cardenas A, Franke RM, et al. Prenatal nicotine sex-dependently alters adolescent dopamine system development. Transl Psychiatry. 2019;9. 15. Counotte DS, Spijker S, Van de Burgwal LH, et al. Long-lasting cognitive deficits resulting from adolescent nicotine exposure in rats. Neuropsychopharmacology. 2009;34:299-306. 16. Counotte DS, Goriounova NA, Li KW, et al. Lasting synaptic changes underlie attention deficits caused by nicotine exposure during adolescence. Nat Neurosci. 2011;14:417-419. 17. Adriani W, Spijker S, Deroche-Gamonet V, et al. Evidence for enhanced neurobehavioral vulnerability to nicotine during periadolescence in rats. J Neurosci. 2003;23:4712-4716. 18. Linker KE, Gad M, Tawadrous P, et al. Microglial activation increases cocaine selfadministration following adolescent nicotine exposure. Nat Commun. 2020;11:306. 19. Slotkin TA, MacKillop EA, Rudder CL, et al. Permanent, sex-selective effects of prenatal or adolescent nicotine exposure in rat brain regions. Neuropsychopharmacology. 2007;32:10821097. 20. Kumari N, Cooke LE, Olsen AL. Proposed mechanisms of neuroprotection for nicotine in Parkinson’s disease. Ther Adv Chronic Dis. 2025. 21. Mishra A, Chaturvedi P, Datta S, et al. Harmful effects of nicotine. Indian J Med Paediatr Oncol. 2015;36:24-31. 22. Benowitz NL. Pharmacology of nicotine: addiction, smoking-induced disease, and therapeutics. Annu Rev Pharmacol Toxicol. 2009;49:57-71.

23. Bencherif M. Neuronal nicotinic receptors as novel targets for inflammation and neuroprotection. Acta Pharmacol Sin. 2009;30:702-714. 24. Bertrand D, Lee CH, Flood D, Marger F, Donnelly-Roberts D. Therapeutic potential of α7 nicotinic acetylcholine receptors. Pharmacol Rev. 2015;67(4):1025-1073. 25. Changeux JP. Nicotine addiction and nicotinic receptors: lessons from genetically modified mice. Nat Rev Neurosci. 2010;11(6):389-401.