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Tobacco use disorder (DSM-5)
Cigarette smoking
A cigarette burning
Synonyms
Synonyms
Tobacco addiction, mental and behavioural disorders due to use of tobacco (ICD-10)
MeSH D014029
ICD-9

305.1

ICD-10

F17

eMedicine

Overview
Presentation
DDx
Workup
Treatment
Medication}

MedlinePlus

000953

Patient.co.uk

Professional Reference
Patient Reference

OMIM

188890

BHC

Smoking - effects on your body

Wikipedia

Smoking cessation (Normal quality)

Tobacco use disorder is a behavioural disorder associated with tobacco use, and is usually an addiction to nicotine and other psychoactive constituents of tobacco.




MechanismEdit

The mechanism of action of nicotine is discussed here. In summary, however, nicotine being a nicotinic acetylcholine receptor full agonist for most subunits, increases cholinergic tone in much of the central nervous system, but especially in the mesolimbic pathway, where its α4β2 and α6β2 subunits predominate. This property enables it induce the release of dopamine into the synaptic cleft, producing euphoria.[1] This euphoria is an automatic reward for drug use that causes repeated use of the drug, until epigenetic changes occur in the individuals brain that cause an addiction.[2] Amongst these changes, include an upregulation of ΔFosB, a transcription factor and inhibition of histone deacetylase activity.[2][3][4]

CausesEdit

Several risk factors for addiction to nicotine have been uncovered, many of them are genetic. It is estimated that about 20-80% of one's odds to start smoking can be directly attributed to genetic factors.[1]:137 Despite this smoking is highly addictive and smokers are twice as likely as cocaine users (via snuffing the powder) to develop an addiction upon first exposure to their respective drug of abuse.[5] People with psychiatric disorders, namely severe depression, schizophrenia or bipolar disorder are also significantly more likely to become addicted to cigarette smoking, which may be partly due to a self-medicating behaviour as nicotine can sometimes help with some of their symptoms.[1]:134-135 For example, in 2000, some 20-30% of the general population and 26-90% of the psychiatric population (dependent on the specific mental illness in consideration) smoked tobacco.[1]:134 Overall the more pleasurable you find smoking, the more likely it is you will become addicted.[1]:134 The genes that are implicated in influencing one's propensity for smoking include the genes involved in the metabolism of nicotine, the genes involved in the creation of the receptor proteins for the nAChRs and the genes involved in the monoaminergic responses to nicotine consumption.[1]:138-145

WithdrawalEdit

Withdrawal is characterized by: irritability, anxiety, depression, restlessness, poor concentration, increased appetite, weight gain and insomnia.[6][7] Weight gain is probably the biggest deterrent from quitting; on average quitting smoking is associated with weight gain of 5 kg in the first year and 6-7 kg overall.[8] But it is worth noting that bupropion and NRT is known to cause some weight loss, in fact, in the U.S. a combination product containing bupropion and phentermine is now approved for the short-term management of obesity.[9] One possible treatment if weight gain is particularly an issue is long-term NRT, even after one has successfully quit smoking.[8]

TreatmentEdit

Non-drug approachesEdit

Behavioural modification therapy, a type of talk therapy can improve (albeit slightly) the rate of successful smoking cessation, along with the drug treatments highlighted in the next paragraph.[10] In the pregnant population it is usually pursued as a first-line treatment.[11] Second-line treatment in pregnant women consists of NRT. The talking approach is considered particularly helpful in those smokers with depression.[12]

Drug-based approachesEdit

There are three cornerstones of drug therapy for nicotine dependence: nicotine replacement therapy (NRT; such as nicotine gum, nasal sprays and patches, e-cigarettes), bupropion and varenicline. Simply talking to one's physician or pharmacist also increases one's odds of successfully quitting.

NRT is usually preferred as it is usually the best combination of safe and effective; it is also available without requiring a prescription in most countries. The major side effects of NRT, include: burning of the mouth and throat, nausea/vomiting (dose-related), increased salivation (that is, producing more saliva than more, which can make you drool), abdominal pain, vomiting, diarrhoea, dizziness, weakness, high blood pressure that is followed by low blood pressure, mental confusion, cold/flu-like symptoms, palpitations, sleep disturbances, vivid dreaming, muscle aches and/or pains, chest pain, anxiety, irritability, sleepiness, menstrual changes, allergic reactions, localized reactions, headache, hearing and visual disturbances, shortness of breath, faintness or seizures. Heart rhythm anomalies may also occur.[7] Localized reactions are basically things that occur near where the nicotine enters the body, such as skin rashes, nasal congestion, etc.[7]

Bupropion, is a noradrenaline-dopamine reuptake inhibitor, hence potentially “taking the edge off” the withdrawals, whilst simultaneously blocking the nAChRs, hence preventing the pleasurable effects of smoking.[13] It is particularly helpful in patients that smoke as a means of self-medicating their depression. The only real problem with it are rare side effects (occurring in fewer than 1% of patients receiving the drug) of seizures (rarely life-threatening; seizures occur in fewer than 0.4% of patients that take it) and anaphylaxis. It may be particularly helpful in smokers with depression or anxiety, as it is also used (albeit rarely, in Australia or the U.K.) to treat depression. Must be dosed two times a day, in Australia and the U.K., can be dosed once a day in the United States, however (see the bupropion page for why). [13]

Varenicline, on the other hand, is a partial agonist at the nAChRs, hence serving two functions, firstly it blocks the pleasurable effects of smoking whilst simultaneously attenuating the symptoms of nicotine withdrawal. Varenicline is believed to be superior to bupropion in as far as the % of people that use it that successfully quit smoking. People receiving varenicline are 2.9 times more likely to succeed in their efforts to quit smoking,[14] whereas those on bupropion are 1.7 times more likely to succeed and those on NRT are 1.6 times more likely to succeed.[15]  Many physicians will try to avoid giving their patients varenicline as it can cause depression (in fewer than 10% of people that take it) and, rarely, suicidal thoughts. 

Cytisine may also be used for smoking cessation; although it is not available for this use in any English-speaking country I am aware of (including Australia, Canada, Hong Kong, the United Kingdom, United States or Singapore).

Less commonly used, yet still supported by the evidence, treatments include:

  • Clonidine.[15] Dose-limiting side effects of sedation and orthostatic hypotension .
  • Nortriptyline.[16] A tricyclic antidepressant that serves, predominantly, as a noradrenaline reuptake inhibitor (NRI); seldom used for this purpose nowadays due to side effects such as urinary retention. 
  • Topiramate. Only one clinical trial supports this use.[17]
  • Rimonabant may also be used but the evidence as to whether it aids smoking cessation in the long-term is inconclusive. It has been withdrawn from the market in most developed countries amidst concerns over increased suicidality in patients treated with it.[18]

Special populationsEdit

Several specific populations are particularly at risk of experiencing tobacco-related harm of they smoke or inhale second-hand smoke. These populations include pregnant or nursing women, children and those with pre-existing conditions like cancer, mental disorders or heart/lung disease.

Pregnancy and lactationEdit

Pregnant women are advised to avoid exposure to tobacco smoking, both first-hand (that is, from them smoking) and second-hand. The complications of smoke exposure during pregnancy include: low birth weight, miscarriage (rate increased by about 10-20%), preterm labour, birth defects (including heart defects, digestive defects, facial defects, etc.; usually by about 10-50%, depending on specific defect), behavioural disorders like attention-deficit/hyperactivity disorder, conduct disorder and sudden infant death syndrome (SIDS).[19][20][21][22] Smoking in this population also seems to come with a racial predilection in Australia: Aboriginals/Torres Strait Islanders are three times more likely to smoke while pregnant than the general population.[23] Second-hand smoke exposure in pregnant women is known to increase the risk of low birth rate.[24]

ChildrenEdit

Smoking in children, luckily, thanks to hard-hitting advertisements of the risk has been on the decrease.[25] Despite this about 80% of all new smokers in Australia are children or adolescents.[26] Passive smoke exposure (that is, second-hand smoke) may stunt growth in children.[27] Likewise, passive smoke exposure in children may increase their risk of SIDS, lower respiratory tract infections (like pneumonia), impair lung function and increase their risk of middle ear disease.[1]:4

People with heart or lung diseaseEdit

Smoking in these populations seems to accelerate the progression of their disease, and while there was some concern that perhaps smoking cessation aids like NRT, bupropion or varenicline could also accelerate the progression of the disease, the general consensus of opinion is that smoking cessation should take priority over everything else, including any theoretical risk for exacerbating these pre-existing conditions.[1]:11[28]

Cancer patientsEdit

Those with cancer are advised to limit their exposure to cigarette smoke as it can cause some pharmacokinetic interactions with their chemotherapeutic agents, likewise it could accelerate the progression of their cancer, this is likely due to a combination of factors, including increased angiogenesis, modified cancer cell survival, etc.[29][30] Fortunately, however, quitting smoke does seem to improve survival in lung cancer patients.[31]

The mentally illEdit

Tobacco is abused amongst those with mental disorders significantly more frequently than by the general population, approximately 70-80% of schizophrenics are smokers, compared to less than 20% for the general population.[32] It is believed that this might be due to a sub-conscious desire to self-medicate themselves, as nicotine is known to improve cognition and some other symptoms of schizophrenia. It may also attenuate some of the side effects of antipsychotic medications. Likewise nicotine is known to relieve anxiety in most smokers. Despite this, it has been found that quitting smoking improves various aspects of mental health, including in the mentally ill.[33] Studies have found that smoking is associated with a two-fold increase in risk for depression in the future.[34] Its association with anxiety disorders is less clear.[35]

Benefits from quittingEdit

In eight hours almost all the excess carbon monoxide in a smoker's body is absent, in five days most of the excess nicotine is out of the body, in one week one's sense of smell and taste improves, in twelve weeks one's lungs regain the ability to clean themselves, at three months one's lung function improves by 30%, at twelve months one's risk of heart disease halves and if one is an Australian your wallet would have gained over $4,500 and in five years one's risk of stroke returns to normal.[36]

NotesEdit


Reference listEdit

  1. 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 U.S. Department of Health and Human Services (2010). How Tobacco Smoke Causes Disease The Biology and Behavioral Basis for Smoking-Attributable Disease A Report of the Surgeon General. Atlanta, USA: U.S. Department of Health and Human Services, Centers for Disease Control and Prevention, National Center for Chronic Disease Prevention and Health Promotion, Office on Smoking and Health. ISBN 978-0-16-084078-4. 
  2. 2.0 2.1 Volkow, ND (2 November 2011). "Epigenetics of nicotine: another nail in the coughing.". Science Translational Medicine 3 (107): 107ps43. PMC 3492949. PMID 22049068. doi:10.1126/scitranslmed.3003278. 
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  5. Brunton, LL; Chabner, BA; Knollmann, BC, ed. (2010). Goodman & Gilman's Pharmacological Basis of Therapeutics (12th ed.). New York, USA: McGraw-Hill Professional. ISBN 978-0-07-162442-8. 
  6. De Biasi, M; Dani, JA (2011). "Reward, addiction, withdrawal to nicotine." (PDF). Annual Review of Neuroscience 34: 105–30. PMC 3137256. PMID 21438686. doi:10.1146/annurev-neuro-061010-113734. 
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  8. 8.0 8.1 Aveyard, P; Lycett, D; Farley, A (2012). "Managing smoking cessation‑related weight gain." (PDF). Polskie Archiwum Medycyny Wewnetrznej 122 (10): 494–8. PMID 23123526. 
  9. Farley, AC; Hajek, P; Lycett, D; Aveyard, P (January 2012). "Interventions for preventing weight gain after smoking cessation.". The Cochrane Database of Systematic Reviews 1: CD006219. PMID 22258966. doi:10.1002/14651858.CD006219.pub3. 
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  14. Cahill, K; Stevens, S; Perera, R; Lancaster, T (May 2013). "Pharmacological interventions for smoking cessation: an overview and network meta-analysis.". The Cochrane Database of Systematic Reviews 5: CD009329. PMID 23728690. doi:10.1002/14651858.CD009329.pub2. 
  15. 15.0 15.1 Zwar, NA; Mendelsohn, CP; Richmond, RL (January 2014). "Supporting smoking cessation.". BMJ 348: f7535. PMID 24423971. doi:10.1136/bmj.f7535. 
  16. Hughes, JR; Stead, LF; Hartmann-Boyce, J; Cahill, K; Lancaster, T (January 2014). "Antidepressants for smoking cessation.". The Cochrane Database of Systematic Reviews 1: CD000031. PMID 24402784. doi:10.1002/14651858.CD000031.pub4. 
  17. Oncken, C; Arias, AJ; Feinn, R; Litt, M; Covault, J; Sofuoglu, M; Kranzler, HR (March 2014). "Topiramate for smoking cessation: a randomized, placebo-controlled pilot study.". Nicotine & Tobacco Research 16 (3): 288–96. PMID 24057996. doi:10.1093/ntr/ntt141. 
  18. Cahill, K; Ussher, MH (March 2011). "Cannabinoid type 1 receptor antagonists for smoking cessation.". The Cochrane Database of Systematic Reviews (3): CD005353. PMID 21412887. doi:10.1002/14651858.CD009329.pub2. 
  19. Hackshaw, A; Rodeck, C; Boniface, S (2011). "Maternal smoking in pregnancy and birth defects: a systematic review based on 173 687 malformed cases and 11.7 million controls.". Human Reproduction Update 17 (5): 589–604. PMC 3156888. PMID 21747128. doi:10.1093/humupd/dmr022. 
  20. Abbott, LC; Winzer-Serhan, UH (April 2012). "Smoking during pregnancy: lessons learned from epidemiological studies and experimental studies using animal models.". Critical Reviews in Toxicology 42 (4): 279–303. PMID 22394313. doi:10.3109/10408444.2012.658506. 
  21. Clifford, A; Lang, L; Chen, R (2012). "Effects of maternal cigarette smoking during pregnancy on cognitive parameters of children and young adults: a literature review.". Neurotoxicology and Teratology 34 (6): 560–70. PMID 23022448. doi:10.1016/j.ntt.2012.09.004. 
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  23. Passey, ME; Bryant, J; Hall, AE; Sanson-Fisher, RW (July 2013). "How will we close the gap in smoking rates for pregnant Indigenous women?". The Medical Journal of Australia 199 (1): 39–41. PMID 23829261. doi:10.5694/mja12.11848. 
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  25. World Health Organization (May 2014). "Tobacco". Media Centre. Geneva, Switzerland: World Health Organization. Retrieved 3 August 2014. 
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  27. Rona, RJ; Chinn, S; Florey, CD (September 1985). "Exposure to cigarette smoking and children's growth.". International Journal of Epidemiology 14 (3): 402–9. PMID 4055207. doi:10.1093/ije/14.3.402. 
  28. Sobieraj, DM; White, WB; Baker, WL (2013). "Cardiovascular effects of pharmacologic therapies for smoking cessation.". Journal of the American Society of Hypertension 7 (1): 61–7. PMC 3549329. PMID 23266101. doi:10.1016/j.jash.2012.11.003. 
  29. Petros, WP; Younis, IR; Ford, JN; Weed, SA (October 2012). "Effects of tobacco smoking and nicotine on cancer treatment.". Pharmacotherapy 32 (10): 920–31. PMC 3499669. PMID 23033231. doi:10.1002/j.1875-9114.2012.01117. 
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  31. Andreas, S; Rittmeyer, A; Hinterthaner, M; Huber, RM (October 2013). "Smoking cessation in lung cancer-achievable and effective.". Deutsches Arzteblatt International 110 (43): 719–24. PMC 3822707. PMID 24222790. doi:10.3238/arztebl.2013.0719. 
  32. Winterer, G (March 2010). "Why do patients with schizophrenia smoke?". Current Opinion in Psychiatry 23 (2): 112–9. PMID 20051860. doi:10.1097/YCO.0b013e3283366643. 
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