Nicotine is an addictive substance found in tobacco products that can act as both a stimulant and a relaxant. Nicotine is available as gums, inhalers, lozenges, nasal sprays, patches, and e-cigarettes and is often sold as a smoking cessation aid. While tobacco is unquestionably dangerous—and smoking tobacco likely increases the risk of dementia—nicotine therapy may offer protection against cognitive decline or dementia, though the evidence is mixed.
The quality of the available research is limited because information on long-term nicotine use in humans comes entirely from the use of tobacco. Our search found:
• 1 meta-analysis of 41 randomized controlled trials examining cognitive outcomes in healthy adults, along with 2 pilot randomized trials in healthy nonsmokers
• 3 randomized controlled trials in Alzheimer's disease patients
• 2 randomized controlled trials in patients with mild cognitive impairment or age-associated memory impairment
• 2 clinical trials in older adults
• Numerous preclinical studies
Smoking tobacco is likely to increase the risk of dementia, and the evidence is mixed on whether nicotine treatment may protect against cognitive decline or dementia. In healthy adult non-smokers, nicotine has improved aspects of fine motor skills, attention, and memory in short clinical trials . However, these effects may be unrelated to the risk of dementia or long-term cognitive decline. For older adults with mild cognitive impairment, nicotine therapy in two small trials led to improvements in some aspects of cognition but not others . A new trial is underway with support from the National Institute of Aging and the Alzheimer's Drug Discovery Foundation to more conclusively test the effects of transdermal nicotine patches for patients with mild cognitive impairment .
In preclinical research, nicotine worsened some aspects of Alzheimer’s disease  and protected against others [8-10].
Nicotine was reported to promote cognition to a greater extent for APOE4 carriers, based on a handful of experiments with healthy adults [11-13], but older smokers with APOE4 were the most likely to have impaired cognition and low brain metabolism . However, APOE4 status did not alter the association of smoking history on disease progression or biological markers of Alzheimer’s disease . For more information on what the APOE4 gene allele means for your health, read our APOE4 information page.
It is uncertain whether Alzheimer's patients might benefit from nicotine therapy. A handful of clinical trials suggested that they are not likely to benefit but a 2001 meta-analysis by the Cochrane Collaboration, an independent global health network, concluded that these trials were of poor quality .
Nicotine therapy not provided through tobacco is well-tolerated but there are some safety concerns such as impaired sleep, addiction, interactions with other drugs, gastrointestinal symptoms, and possible cardiovascular effects. Nicotine poisoning or overdose can occur and children are especially vulnerable . Some individuals may have health conditions that substantially increase the risks of side effects. Most experts agree that nicotine is highly addictive , although some scientists argue that tobacco is addictive but not because of nicotine . Nicotine interacts with many other drugs so the use of other medications can impact the safety of nicotine treatment.
NOTE: This is not a comprehensive safety evaluation or complete list of potentially harmful drug interactions. It is important to discuss safety issues with your physician before taking any new supplement or medication.
Nicotine replacement therapy is marketed to help people stop using tobacco. It is available as patches, gum, and lozenges that can typically be purchased over the counter and as inhalers and nasal sprays that require a doctor’s prescription. In small clinical trials, the dose of nicotine that improved some aspects of cognition ranged from 5 to 15 mg/day . Higher doses likely have greater risk of sleep side effects .
Download full scientific report
The American Cancer Society Guide to Quitting Smoking
Check for drug-drug and drug-supplement interactions on Drugs.com