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Therapeutic uses
The primary therapeutic use of nicotine is in treating nicotine dependence in order to eliminate smoking with the damage it does to health. Controlled levels of nicotine are given to patients through gums, dermal patches, lozenges, electronic/substitute cigarettes or nasal sprays in an effort to wean them off their dependence.
However, in a few situations, smoking has been observed to apparently be of therapeutic value. These are often referred to as "Smoker’s Paradoxes".[63] Although in most cases the actual mechanism is understood only poorly or not at all, it is generally believed that the principal beneficial action is due to the nicotine administered, and that administration of nicotine without smoking may be as beneficial as smoking, without the higher risk to health due to tar and other ingredients found in tobacco.
For instance, recent studies suggest that smokers require less frequent repeated revascularization after percutaneous coronary intervention (PCI).[63] Risk of ulcerative colitis has been frequently shown to be reduced by smokers on a dose-dependent basis; the effect is eliminated if the individual stops smoking.[64][65] Smoking also appears to interfere with development of Kaposi's sarcoma in patients with HIV,[2].[66]
Nicotine reduces the chance of breast cancer among women carrying the very high risk BRCA gene,[67] preeclampsia,[68] and atopic disorders such as allergic asthma.[69] A plausible mechanism of action in these cases may be nicotine acting as an anti-inflammatory agent, and interfering with the inflammation-related disease process, as nicotine has vasoconstrictive effects.[70]
Tobacco smoke has been shown to contain compounds capable of inhibiting MAO. Monoamine oxidase is responsible for the degradation of dopamine in the human brain. When dopamine is broken down by MAO-B, neurotoxic by-products are formed, possibly contributing to Parkinson's and Alzheimers disease.[71] Many such papers regarding Alzheimer's disease[72] and Parkinson's Disease[73] have been published. Recent studies find no beneficial link between smoking and Alzheimer's disease and in some cases, suggest it may actually result in an earlier onset of the disease.[74][75][76][77] However, nicotine has been shown to delay the onset of Parkinson's disease in studies involving monkeys and humans.[78][79][80]
Recent studies have indicated that nicotine can be used to help adults suffering from autosomal dominant nocturnal frontal lobe epilepsy. The same areas that cause seizures in that form of epilepsy are responsible for processing nicotine in the brain.[81]
Studies suggest a correlation between smoking and schizophrenia, with estimates near 75% for the proportion of schizophrenic patients who smoke. Although the nature of this association remains unclear, it was recently argued that the increased level of smoking in schizophrenia may be due to a desire to self-medicate with nicotine.[82][83] More recent research has found that mildly dependent users got some benefit from nicotine, but not those who were highly dependent.[84] All of these studies are based only on observation, and no interventional (randomized) studies have been done. Research on nicotine as administered through a patch or gum is ongoing.
Nicotine appears to improve ADHD symptoms. Some studies are focusing on benefits of nicotine therapy in adults with ADHD.[85]
Nicotine (in the form of chewing gum or a transdermal patch) is being explored as an experimental treatment for OCD. Small studies show some success, even in otherwise treatment-refractory cases.[86][87][88]
