Motivation and emotion/Book/2015/Nicotine and addiction

Nicotine and addiction:
Why is nicotine addictive and what can be done about it?

Overview edit

 
Figure 1. Anti-smoking advert from the 1980s

Nicotine and the effects of addiction to this substance has received increasing research attention since the late 1970s as the habit of smoking has become more common over the years and is currently the leading preventable cause of death all over the world (World Health Organization, 2011). The DSM-V has enlisted in the latest version of the manual, a Tobacco-Related Disorders criterion. Tobacco use disorder is “a problematic pattern of tobacco use leading to clinically significant impairment or distress, as manifested by at least two of the [listed factors], occurring within a 12 month period”. The diagnostic features state that many individuals suffering from this disorder use tobacco to relieve or avoid withdrawal symptoms and have physical symptoms or diseases yet continue to smoke despite the downsides. Research has identified several effects that nicotine can have on the brain, the main one being the release of neurotransmitter dopamine, which is related to feelings of pleasure, resulting in an increased level of pleasure through the reward circuit in the brain. Motivation to smoke is also encouraged by the feel, smell and sight of a cigarette as the ritual of lighting and holding the cigarette are all associated with the pleasure of the habit, which is a contributing factor to the ongoing pattern of smoking and refusal to quit.

If you are a smoker or know a smoker, this book chapter could act as a useful asset to understand the implications of smoking, the motivation behind this habit, due to which people continue to smoke regardless of the life threatening side effects, as well learn what can be done about it e.g. quitting support, remedies that result in a reduction of nicotine intake, etc.[Rewrite to improve clarity] Once you have read this book chapter, take a look at the interactive quiz as well as the multimedia explanation given at the end to supplement learning and test your knowledge. Please take the 'test your knowledge' quiz at the end of this chapter to test your awareness of the motivation behind smoking and what can be done about it.

Addiction edit

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How do you identify the level of addiction? edit

An addiction, according to the National Institute on Drug Abuse ,is a chronic, relapsing brain disease that is characterized by compulsive drug seeking and use, despite harmful consequences. A range of different social and environmental factors can contribute to an addiction i.e., just how much any individual uses a drug. Fagerstrom, Heatherton and Kozlowski state that “if the environment encourages smoking in that those with whom you live and work are likely to be smoking, then the intake of the cigarettes and nicotine is likely to be well above the lower boundary level[explain?]”. Their experiment used the Fagerstrom Test for Nicotine Dependance (FTND) in the form of a survey to explore the different factors that contribute to this deadly habit. The FTND is a test, which is known to be a useful asset to physicians all over the world to determine an individual’s level of nicotine dependence. It assesses the amount of points an individual collects by answering simple addiction related questions e.g. how soon after you wake up do you smoke your first cigarette, do you smoke if you are so ill that you are in bed most of the day, etc; the higher your collection of points from answering the questions, the higher your addiction level. Physicians have also found the test useful in order to determine the right treatment adjusted to each individual depending on their symptoms and habits; this is calculated so that the right nicotine quitting treatment is given to liberate the addiction.

What factors contribute to nicotine-intake? edit

Certain well-researched factors have tried to evaluate on addiction[say what?][Rewrite to improve clarity], particularly to nicotine, and the variations in daily smoking rate and timing. These include:

  1. Emotional distress: According to Shiffman, Gwaltney, Balabanis, Liu, Paty, Kassel, Hickcox and Gnys (2002), evidence suggests that smoking follows a discernable pattern and is particularly likely to occur in certain situations, such as emotional distress. This stress could be caused by relationships at home, with friends or even an individual’s work environment.
  2. Alcohol and Caffeine consumption: Studies have shown that alcohol consumption as well as caffeine intake correlates positively with nicotine intake. Istvan and Matarazzo (1984) state through empirical research that caffeine and tobacco use as well as alcohol and tobacco use are moderately to strongly related whereas alcohol and caffeine consumption doesn’t have a significant interrelationship.
  3. Mood and mood regulation: Studies have shown a correlation between mood and smoking. You often hear people say to smokers when they display anger to “have a smoke” or “you need to have a smoke and calm down”. This is because “indices of frontal lobe dysfunction have also been associated with chronic smoking, raising the possibility that deficient frontal lobe functioning may underlie mood difficulties in smoking.[factual?][Rewrite to improve clarity]

Physiological effects associated with Nicotine edit

 
Figure 2. Change in cigarette packaging to discourage smoking by visually deterring the results of the habit[grammar?].

As mentioned in the overview, research has identified several effects that nicotine can have on the brain, the main one being the release of dopamine, which can significantly increase the level of pleasure through the reward circuit in the brain. These effects are known to rapidly distribute through the brain with drug levels peaking within just 10 seconds of inhalation of a cigarette however the effects are known to dissipate quickly motivating the smoker to maintain the habit for the constant feelings of pleasure and prevent withdrawal (National Institute of Drug Abuse, 2012). A study by Lyvers, Carlopio, Bothma and Edwards (2014) confirmed that indices of the frontal lobe dysfunction is[grammar?] also closely related to chronic smoking raising and confirming the possibility that deficient frontal lobe functioning may underlie mood difficulties in smokers. There are also some studies that suggest that nicotine can act as an anti-depressant for smokers as it is used as a means to relieve of stress and elevate mood levels and others that suggest nicotine has a diminishing effect on happiness and contributes to mood depression[factual?]. So which is it? A study done by Shahab and West in 2012 reported findings from a large UK sample consisting of current smokers, ex-smokers and never-smokers. Findings showed that smoking worsens mood as current smokers reported a much lower level of happiness in comparison to the ex-smokers (who had quit for longer than a year) and never-smokers showing evidence of eventual improvement on mood once a smoker has quit[say what?][Rewrite to improve clarity]. Tobacco Dependence resembles a drug addiction in more ways than not; both drug and nicotine users show agitated symptoms when they haven’t had their ‘hit’ for the day and the craving pattern is very similar as it’s characterized by frequent negative mood and executive dysfunction symptoms. Once the brain has figured out how it worked pre-smoking, mood is elevated, negative and withdrawal symptoms decrease and post-quitting processes such as dopamine levels returning to normal etc, are also mended (Lyvers, et. al., 2014).

Symptoms of withdrawal and Side Effects edit

The symptoms of withdrawal include “irritability, craving, depression, anxiety, cognitive and attention deficits, sleep disturbances and increased appetite” to name a few thus withdrawal-related symptoms become a strong cue for continuous smoking. If an individual decides to let go of the habit of smoking and finds him or herself under a lot of pressure under which they would have normally turned to smoking to relieve stress, they can find themselves in a panic possibly resulting in taking up the habit again. According to an article by Christensen et al., (2014) states that adolescences have been shown to exhibit symptoms of addition[spelling?] to nicotine within a few weeks of limited exposure such as two cigarettes a week, and withdrawal symptoms can appear just two days after their first cigarette. Scientists predict that this is due to the nicotine being more excitatory in the young within the neurobiological reward circuitry involved in assigning a positive valiance to environmental stimuli. This statement in[spelling?] generally applicable to adolescents who take up smoking in their prime years and can be used to define the addictive substances in some of the other drugs and their implications. It has been noted though that the human body stops craving the nicotine itself after approximately a week of no-smoking however it is the psychological effects or habits associated with smoking itself that contribute to the urges. Social situations and environmental factors are also known to contribute to relapse as they are things you used to associate with smoking e.g. parties on a Saturday night or dinner every night can remind you of the cigarette you used to have directly after finishing the meal. Withdrawal is a tough part of smoking and can produce so many negative effects in the body which can lead to depressive mood symptoms, anger/rage, having to say no to certain events to avoid being put in the situation to smoke knowing the chances of relapse are high[factual?]. In the long run, these symptoms of withdrawal are likely to decrease with time and cravings are known to not affect an individual nearly as badly as it would have up till about 6 months post-quitting.

Australia – What is being done to reduce the number of people who smoke and is it effective? edit

Nicotine is an addictive drug, for many reasons mentioned so far in this chapter and although Australia has contributed to many economical changes to bring down the number of smokers by raising economical prices, advertising the negative effects of smoking, etc - the [what?]numbers have not come down as much as Australia had hoped[factual?].

Although medical knowledge of smoking and its implications have been advertised and discussed in the media since the early 1900s, it wasn’t until the early 1980s that the government along with the cancer council [grammar?] seriously began to challenge the tobacco companies with the use of mass media; along with this change, quit campaigns came into motion as well as national quit-lines to support those who wanted to quit, in their journey. It was also around this time that the effects of second-hand smoke were discovered which “led courts and various tribunals concerned with workers’ health and safety to award compensation for sickness arising from exposure to tobacco smoke in the workplace, which sent a powerful signal to governments and the private sector about the need to protect citizens from second-hand smoke” (Tobacco In Australia, 2012). Since then, we have seen certain public places, such as offices, café’s as well as nightclubs to name a few, ban smoking within the inside of the venue and assigned smoking area’s for those who wish to smoke. Australia became a Signatory to the WHO Framework Convention on Tobacco Control (FCTC) on the 5th December 2003 becoming one of the first 40 countries to ratify the FCTC and became a full party within 2 years after the sign date. This petition gave Australia the power to put anti-smoking policies into place and go to the farthest extents to reduce the number of individuals in Australia who smoke.

 
Figure 4. Statistics to show the number of smokers decreasing per year in Australia due to rules and regulations discouraging smoking

Australia also started to advertise the negative effects of smoking on the cigarette packaging and reducing the appeal and glamour of tobacco products in September 2012. Warning signs with bright yellow backing took over the packaging of cigarettes along with information on the back as to how people die from the dangerous addiction. All states and territories in Australia banned smoking in enclosed public spaces such as public transit, office buildings, shopping malls, schools and cinemas in 2003 whereas outdoor café’s, clubs and pubs as well as underage functions prohibited smoking as of 9th December, 2010 (Tobacco in Australia, 2012). A legislation prohibiting smoking within cars when children under the age of 16 years are present was passed in October 2011 and came into effect in 2012 (Tobacco in Australia, 2012). The age that the ban applied to ranged from 16-18 in different states across Australia e.g. for Victoria, cars carrying passengers under the age of 18 banned smoking and WA banned smoking in cars carrying passengers under the age of 17. Economically, taxes on smoking have also rapidly increased in order to condense the number of smokers across the country by adding a financial barrier to the habit. Each year, smoking kills as estimated 15,000 Australians and costs Australia $31.5 billion in social and economic costs (Department of Health, 2015). The Government of Australia brought in a plan on the 6th November 2013 to implement four different excise increases in tobacco by 12.5% each time. The first 12.5% increase was motioned on December 1, 2013, second on the September 1, 2014, third on September 1, 2015 and the last one is due to commence on September 1, 2016. The government stated that this is also a way for them to control young people from smoking as they are more price-sensitive than adults and won’t purchase packets if the price is their entire week’s pocket money. As can be seen by the factors listed above, Australia has taken immense measures to prevent passive smoking as well as eliminate the high numbers of individuals across the country who are motivated to smoke regularly.

In 2011-12, Australia consisted of 16.1% of the total population (equating to 2.8 million citizens aged 18 and over) who smoked daily. The attempts to reduce smoking in Australia by putting certain rules and regulations into place significantly succeeded as daily smoking numbers have decreased consistently over the past decade from 18.9% in 2007-08 and 22.4% in 2001. Statistics also show that people within the 15-17 year age group, 4.2% of the youth took on smoking as a daily habit, 1.7% smoked less often than daily and 4.2% were ex-smokers (Australian Bureau of Statistics, 2011). As can be proven by this statement with numerical evidential support, the age of people who take up smoking is decreasing every year. The generation today is a lot more advanced than the older generations as the age where people start drinking is heavily decreasing (illegally) and smoking falls in the same spectrum.

Quitting edit

In Australia, approximately 40% of the smoking population attempts to quit each year out of which, only about half successfully maintain abstinence from smoking for a one-month period. There are a number of resources available, on the Internet, phone and in person that are there to assist people on their journey to quit nicotine.

Online: edit

Technology has become a big part of ur[spelling?] lives today,[grammar?] this is why Australia has set up various quit-line's on the net to provide methods to quit e.g. ‘iCanQuit.com.au’, ‘QuitNow.com.au’ as well as ‘NailQuitting.com.au’. ‘iCanQuit’ and ‘QuitNow’ are both industries that are largely advertised across Australia from cinema screens, to ads at the local bus-stop – they cover the premises as much as they can to encourage getting help if you are a smoker. Figure 3 shows an image captured from the ‘iCanQuit’ website showing how much money you could be saving if you quit smoking. The figures entered into this calculation set were 12 cigarettes smoked per day, $24.99 per packet containing 25 cigarettes each’. This data set is calculated to motivate people to stop spending their money on nicotine and instead save that money to put towards bigger, better things such as the examples of what the weekly, monthly and yearly value could buy them. ‘QuitNow’ offers a similar online support system for those addicted to Nicotine but is focused more on educating the population on how quitting can benefit physical and mental health of individuals. In Figure 4, you can see that the website homepage consists of various links, each of which is educational in understanding coping strategies, steps to prepare for letting go of the habit, etc. ‘QuitNow’ also has 2 apps to help people quit, one aimed at regular smokers and one designed to help pregnant women quit. The website also offers what they call a ‘Quit Coach’ which is a powerful tool designed to help each and every individual gain a personalized plan based on responses to questions regarding motivation, confidence as well as past attempts to quit. Research has shown that the Quit Coach can double one’s chance of quitting smoking by helping the individual understand their addiction, know exactly what to expect when quitting, providing strategies to help resist urges to smoke as well as starting to think and feel like a non-smoker.

Phone: edit

Mentioned above are two of the largest companies motivating people through daily campaigns and advertising to quit smoking with online methods but what makes them so encouraging is also their Quitlines. ‘iCanQuit’ also offers a hotline in NSW which is there to help assist people if they are likely to feel more motivated by speaking to someone as oppose to getting help with the use of technology. Their hotlines are open Monday to Friday from 7am to 10.30pm and on weekends and public holidays from 9am till 5pm offering individuals a vast timeline to get the help that they need outside of work hours or after any commitments in the day. What makes Australia and these quit-lines even better is their understanding of the different cultures and accommodating for language barriers that is why interpreters are offered for those who are not fluent English speakers so help is there for every person, from every culture. ‘QuitNow’ also offers a 24 hour hotline service which has been set up to provide individuals advice and counseling services in regards to quitting smoking. The service is also 100% confidential so for those who are afraid to speak to friends and family with the fear of being judged about the way that they feel in relation to smoking, still have a way to get advice and the relevant help that they need to feel supported in their journey back to health.

The 3 successful methods of quitting according to iCanQuit include:

  1. Cold turkey – Deciding to quit all of a sudden and never looking back
  2. Cut down – Make a plan to cut down and decrease the number of cigarettes smoked per day consistently
  3. Nicotine Replacement – Replacing the nicotine with something else, preferably something which will make you look back and feel pleased that you quit e.g. exercise


Pharmacotherapy Nicotine Replacement edit

There are a lot of different and new ways to assist a smoker with the quitting process. [1] is a company that came about in 2000’s and has developed rapidly since its introduction from having one product to assist quitting to having 6 different kinds of therapy products. Their products include:

  1. Patches
  2. Oral Strips
  3. Minis
  4. Lozenges
  5. Gum
  6. Combo therapy

All of these products are now stocked at most pharmacies available to purchase and are all designed to make the journey to quitting as easy as possible. All of the products mentioned above have a given timeline in which they shall start to be effective so patience is key and setting goals that are achievable is what will make the journey effective.

Nicotine Addition and Psychological Theories edit

Goal-Setting Theory edit

Locke and Latham (1990) developed the goal setting theory, which bases its assumption based on final causality, which is an action caused by a purpose. The theorists believed that the more difficult the goal, the greater the achievement. There are five given principles to the goal-setting model to motivate; these include:

  1. Clarity
  2. Challenge
  3. Commitment
  4. Feedback
  5. Task complexity

Clarity goals are clear and specific and have an assigned time bound on completion.

Challenge goals measure the level of the task difficulty as well as the achievement level based on the significance of the anticipated accomplishment.

Commitment goals must be understood and agreed upon if achievement is the goal. The individual needs to participate in the goal setting process and decide upon achievable steps to commit to in order to follow through on the end result.

Feedback goals provide an individual with opportunities to clarify expectations, adjust goal difficulty (if need be) and gain recognition. This can also be an individual who is gaining help from other sources to achieve their goal e.g. a quit line, friend, and/or counselor. These authorities could then provide the individual with feedback for improvement or encouragement giving them recognition for their efforts along the way.

Task Complexity goals being the last step of the model, is there to ensure that the goal achievement isn’t getting too overwhelming for the individual for those who have goals that are high in complexity and demanding. This can mean that the time limit of task completion needs to be extended to become more achievable.

In regards to individuals with a Nicotine addiction, the goal-setting theory can be a useful tool to assist the quitting process by providing step by step guidelines to set a goal, and follow through in order to achieve the desired result. Through a range of research, Edwin A Locke and Gary P. Latham found a “positive, linear function in that the highest or most difficult goals produced the highest levels of effort”. Overall, the goal setting theory acknowledges the importance of conscious goals as well as self-efficacy resulting in motivation to accomplish the goals one has set for him or herself.

Theory of Planned Behaviour edit

 
Figure 1. Figure 5. Ajzen’s Theory of Planned Behavior Model

The Theory of Planned Behaviors (TPB) was developed by Ajzen’s in 1988 and has emerged as one of the most influential conceptual frameworks in motivational psychology. This theory states that “human behavior is guided by three kinds of considerations: beliefs about the likely consequences or other attributes of the behavior (behavioral beliefs), beliefs about the normative expectations of other people (normative beliefs) and beliefs about the presence of factors that may further or hinder performance of the behavior (control beliefs)” (Ajzen, 2002).

This model has been developed in order to use subjective norms in order to determine one’s intentions to then with those intentions, determine the relevant effects it has on one’s behavior therefore in this case study, quitting smoking would be the determined intention by which the behavior should indicate the relevant steps that need to be taken to achieve the intention. A study done by Norman, Conner and Bell (1999) showed results from two studies exploring the TPB and smoking cessation. In the first study, a general population sample of smokers was studied to further gain knowledge into perceived behavioral control. The results showed that “behavioral intention was in turn related to smoking behavior 6 months later, although the effect of behavioral intension[spelling?] was removed when perceived behavioral control was added to the regression equation”. The second study also gained insight into behavioral control having a strong correlation with both intentions and behavior with the sample consisting of pregnant women. The first study followed a workplace ban where 6 months was primarily predicted by the population’s desire to quit and successful cessation evaluated habit strength. This study does state that those who had been motivated to quit and made previous attempts to let go of smoking habits may have had an advantage in that they had acquired skills and strategies in high relapse situations, assisting them to quit again and increasing their likelihood of succeeding. Such factors need to be taken into account before determining the success-rate of a theory as some limitations can predict inconclusive results due to unknown factors.

Once the desired behavior has been identified within the accessible memory, it is only then that the planned behavior can be carried out with the use of a plan including a direct measure of attitude, subjective norms, perceptions of behavior control as well as one’s actual behavior. The TPB allows an individual to feel in control of the overall situation and motivate them furthermore to quit as they have organized the plan, and it has to be carried out by them.

Conclusion edit

This chapter has hopefully provided you with the relevant skills and knowledge to either help you quit smoking, or assist a friend or family member to let go of this dangerous habit which is a controllable leading cause of death. The negative effects of such a habit are extremely harmful in more ways than one and the risk of permanent damage is high, as the smoking packaging advertises. The most recent statistics support the claim that the number of smokers across the [which?] country have significantly decreased on a continuum. Australia has taken some drastic measures to eliminate the high numbers of the population from smoking by taxation, relevant real-life stories being advertised on the packaging and restricting the number of places where smoking is permitted. Motivation to smoke comes from a range of different factors which can vary between each individual from stress to social smoking but this is why there are so many different options offered in today’s generation to offer people full support in their journey to a healthier lifestyle of no-smoking. By setting goals and making plans, a lot more is achievable. If you have relapsed, know that the next time you motivate yourself to quit smoking, your likelihood of success is even greater so don’t give up, stay motivated!

Test your knowledge edit

1 What are two factors that contribute to the amount of nicotine an individual inhales:

Emotional Distress
Hunger
Mood Regulation
An excuse to exercise

2 Which of the four symptoms of withdrawal is not mentioned as a side effect of quitting smoking?

Irritability
Craving
Performance
Depression

3 Which of the following is not a Nicabate product?

Oral Stips [spelling?]
Mouth Spray
Gym
Patches
None of the above


See also edit

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References edit

Ajzen, I. (1991). The Theory of Planned Behavior. Organisational Behaviour and Human Decision Processes, (50), 179-211. doi:0749-5978/9

Australian Bureau of Statistics,. 'Tobacco Smoking'. N.p., 2015.

Christensen, M., Ishibashi, M., Nielsen, M., Leonard, C., & Kohlmeier, K. (1st September 2014). Age-related changes in nicotine response of cholinergic and non-cholinergic laterodorsal tegmental neurons: Implications for the heightened adolescent susceptibility to nicotine addiction. Neuropharmacology, (85), 263-283. Retrieved November 1, 2015.

Get support. (2012, May 20). Retrieved November 2, 2015, from http://www.quitnow.gov.au/internet/quitnow/publishing.nsf/Content/get-support

ICanQuit, Quit Smoking online Resources, Quit Smoking NSW. (2015). Retrieved November 1, 2015, from https://www.icanquit.com.au

Immediate Antecedents Of Cigarette Smoking: An Analysis From Ecological Momentary Assessment. Journal of Abnormal Psychology, 111(4), 531-545. doi:10.1037//0021-843X.111.4.531

Is Nicotine Addictive? (2012, July 1). Retrieved November 1, 2015, from http://www.drugabuse.gov/publications/research-reports/tobacco/nicotine-addictive

Istvan, J., & Matarazzo, J. (1984). Tobacco, alcohol, and caffeine use: A review of their interrelationships. Psychological Bulletin, 95(2), 301-326.

Products - Smoking Cessation and Nicotine Replacement Therapy - Nicabate. (2015). Retrieved November 1, 2015. Nil, R., Buzzi, R., & Bättig, K. (1983). Effects of single doses of alcohol and caffeine on cigarette smoke puffing behavior.

Pharmacology Biochemistry and Behavior, 20, 583-590. doi:0091-3057/84 Locke's Goal-Setting Theory: Understanding SMART Goal Setting. (n.d.). Retrieved November 1, 2015, from http://www.mindtools.com/pages/article/newHTE_87.htm

Locke, E. A., & Latham, G. P. (2002). Building a practically useful theory of goal setting and task motivation: A 35-year odyssey. American Psychologist, 57(9), 705-717. doi:10.1037/0003-066X.57.9.705

Lyvers, M., Carlopio, C., Bothma, V., & Edwards, M. (2014). Mood, Mood Regulation, and Frontal Systems Functioning in Current Smokers, Long-Term Abstinent Ex-Smokers, and Never-Smokers. Journal of Psychoactive Drugs, (46), 133-139. doi:10.1080/02791072.2013.876522

Norman, Paul, Mark Conner, and Russell Bell. 'The Theory Of Planned Behavior And Smoking Cessation.'. Health Psychology 18.1 (1999): 89-94. Web.

Ray, R., Loughead, J., Wang, Z., Detre, J., Yang, E., Gur, R., & Lerman, C. (2008). Neuroimaging, genetics and the treatment of nicotine addiction. Behavioural Brain Research, (193), 159-169.

Reeve, J. (n.d.). Understanding motivation and emotion (Sixth ed.).

Rose, J. (2004). Nicotine and nonnicotine factors in cigarette addiction. Psychopharmacology, (184), 274-285. doi:10.1007/s00213-005-0250-x

Shahab, L. & West, R. 2012. Differences in happiness between smokers, ex-smokers and never-smokers: Cross-sectional findings from a national household survey. Drug and Alcohol Dependence 121: 38–44.

Shiffman, S., Gwaltney, C., Balabanis, M., Liu, K., Paty, J., Kassel, J., . . . Gnys, M. (2002).

Selya, A., Updegrove, N., Rose, J., Dierker, L., Tan, X., Hedeker, D., . . . Mermelstein, R. (2015). Nicotine-dependence-varying effects of smoking events on momentary mood changes among adolescents. Addictive Behaviors, 41, 65-71. doi:10.1016/j.addbeh.2014.09.028

Tobacco control. (2015, August 13). Retrieved November 2, 2015, from http://www.health.gov.au/tobacco

Tobaccoinaustralia.org.au,. '15.7 Legislation To Ban Smoking In Public Spaces - Tobacco In Australia'. N.p., 2015.

Quit Now. (2012, May 30). Retrieved November 1, 2015, from http://www.quitnow.gov.au

Wang, Z., Ray, R., Faith, M., Tang, K., Wileyto, E., Detre, J., & Lerman, C. (16 April, 2008). Nicotine abstinence-induced cerebral blood flow changes by genotype. Neuroscience Letters, 275-280.

External links edit

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