Motivation and emotion/Book/2013/Nicotine and emotion
What is the effect of nicotine on emotion?
Overview[edit | edit source]
Nicotine is a powerfully addictive substance that has been used in various applications for thousands of years. Whether or not you are a regular smoker, the act of smoking or even observing others smoking raises a lot of thoughts, feelings and emotions. Consider the last time you stood next to somebody in a crowded outdoor shopping district who was smoking a cigarette? How did this make you feel? Did you silently curse them and move away? Or did you join them, light up, and strike a conversation? And what about the last time you arrived home after a stressful day? Did you feel the urge to light up to relax? Consider now when you were at a fantastic backyard party celebrating your best friend's sixteenth birthday. Did you feel pressure to ignore your parent’s parting advice to just ‘say no’ to drugs and alcohol? Does one cigarette count? After all, it’s only one.
The following is part of a larger collection of motivational resources aimed to improve your life. This chapter will examine the effects of nicotine on emotion and hopefully provide you with some useful, psychologically sound, information and strategies to help you come to your own conclusions about whether you need nicotine in your life. A key point throughout this chapter emphasises that the individual always has the intrinsic strength to just say no. Nicotine has a vice-like emotional and physiological grip on smokers who feel afraid or powerless to quit and often recognising this damaging cyclic relationship is the first step to quitting for good.
Nicotine through history[edit | edit source]
Nicotine is the addictive chemical substance derived from the tobacco plant. For many centuries tobacco has been used as a traditional medicine and ceremonial tool. The ancient Native Americans had purportedly used tobacco products for thousands of years in cultural rituals and as a medicinal wound application before early European settlers to the region exported tobacco to the rest of the world as a product of leisure (Musk & De Clerk, 2003).
The 1800s saw the earliest development of the modern cigarette in handmade finely rolled paper cigars that into the 20th century were commercially produced as cigarettes. During this time a rapid increase in cigarette consumption occurred in the developed world, particularly during World War 1 (Musk & De Clerk, 2003). The mass produced modern cigarette not only includes tobacco leaf blend, but also hundreds of flavour enhancing chemicals and additives known to cause addiction and health problems (NSW Government Health, 2007). As early as the 1880’s, cigarettes were already colloquially referred to as ‘coffin nails’ (Cook, 2007), in recent decades health and science research has repeatedly detailed the harmful physiological effects of nicotine consumption in all its forms including smoking, chewing, snorting and dipping.
Research indicates that 1 in 5 Americans will die from tobacco related deaths such as lung cancer, cardiovascular disease and pulmonary disease. Despite these figures over 45 million people in the USA alone currently smoke tobacco. This represents just under 20% of America's population; a small percentage compared with just under 40% for Germany and Japan (Cutler & Glaeser, 2009). Furthermore, tobacco related deaths are the leading cause of preventable death worldwide (Cahill, Stead, & Lancaster, 2011). Despite clear detrimental effects to health, people are still motivated to consume nicotine worldwide (Benowitz, 2010).
Physiological level analysis[edit | edit source]
Reward[edit | edit source]
Nicotine is a chemical agonist, meaning that it excites, rather than inhibits, neuronal activity within the brain. When consumed, nicotine cells bind to the acetylcholine nicotinic receptors in the postsynaptic neuron within the central nervous system. Here they stimulate the release of dopamine, the neurotransmitter associated with reward and repeated behaviours, at the brain site known as the Nucleus Acumbens. When dopamine release is increased at this site, the individual will experience rewarding, approach oriented cognitions and emotions toward the consumption of nicotine and the behavioural process of smoking is reinforced. However, over time, these particular receptors become dulled to the nicotine stimulus and thus require increased amounts to produce the desired effect. This is called building a tolerance. The addictive properties of nicotine ensure the individual seeks out increased nicotine to meet the growing tolerance and avoid emotionally draining, uncomfortable, even painful withdrawal symptoms (Cahill, Stead, & Lancaster, 2011).
Withdrawal[edit | edit source]
Nicotine Withdrawal (NW) is recognised in the DSM-V as a pathological condition that may arise when the dopamine release in the Nucleus Accumbens associated with nicotine consumption is suddenly disrupted. Symptoms in the individual may include distinct emotional changes and heightened pre-existing traits, moods and pathological symptoms such as increased neuroticism, anxiety, depression, irritability, frustration and anger as well as dependence on other substances or alcohol. Additionally, physiological symptoms may include headaches, changes in appetite, trembling and sweating common to other drug withdrawals (5th ed.; DSM–V; American Psychiatric Association [APA], 2013).
Psychophysiological effects of nicotine in non-smokers[edit | edit source]
While regular smokers will generally feel satisfaction from the dopaminergic reward of smoking, non-smokers can feel an opposite effect. Non-regular smokers may report a more intense head-rush or dizziness, heightened sensitivity to unpleasant stimuli and increased neural activity within a brain pathway known as the amygdala-perigenual anterior cingulate cortex (pACC) an area implicated in emotional processing, error detection and conflict resolution. Additionally, it was found that non-smoking individuals who displayed increased activity in this region reported higher anxiety post-inhalation of nicotine. These findings contributes to our understanding of the diversity of nicotine effects on emotion, both at a physiological and cognitive level.
The Nicotine Paradox: Differing emotional effects of nicotine on the individual[edit | edit source]
[edit | edit source]
For many individuals smoking is a valuable tool used to control stress and regulate negative emotion in the short-term. In the long-term however smoking actually aggravates negative emotional states and stress. Many smokers are aware of this paradox, fear losing emotional control and therefore may smoke more to alleviate immediate stress. This creates a circular notion of 'I smoke because i'm unhappy; I'm unhappy because I smoke'. This circular relationship is sometimes called the smoking-stress link. Therefore, it may be empowering for smokers to consider that if cigarettes were withdrawn from the equation, the power to regulate emotions is not determined by cigarettes, but is instead inherent to the individual (Hajek, Taylor, & McRobbie, 2010).
Tobacco is used as both an emotional stimulant and relaxant (Balogopal et al., 2012). Individuals who feel more relaxed when smoking are more likely to report symptoms of nicotine dependence (Ursprung, Savageau, & DiFranza, 2011). Individuals who are motivated to seek the relaxant effects of nicotine are more likely to experience emotional tension, hypersensitivity and anxiety during withdrawal (Carton, Houezec, Lagrue & Jouvent, 2000). By contrast, individuals who seek the stimulant effects of nicotine are more likely to experience anhedonia, or blunted affect, during withdrawal (Carton et al., 2000). Additionally, those who regularly use other stimulant drugs are more likely to feel stimulant effects from nicotine (Weinberger & Sofuoglu, 2009).
To help explain these differences, lower doses of nicotine are associated with relaxant or depressant effects, whereas larger doses are associated with stimulant effects. Furthermore, these effects are determined by the individual's preexisting affect, external environment and circumstances of nicotine use. For example, those smoking at a social gathering where positive affect is high, such as a party, are more likely to feel stimulant effects from nicotine. In contrast an individual smoking alone after a stressful day at work is more likely to feel the relaxant effects of nicotine (Balogopal et al., 2012). Consequently, both outcomes are associated with the dopamine reward of stimulation and relaxation. Therefore nicotine and emotion have a complex relationship as demonstrated in Figure 1. In this relationship the effects of nicotine regulate an individual's affect and in turn affect, external environmental stimuli and circumstances of nicotine consumption all help determine the stimulant or depressant effects of nicotine.
When deprived of the effects of nicotine, the individual can experience cravings during both abstinence and relapse. For the addicted individual, these cravings are so intense they produce the physiological necessity to continue smoking. Many individuals report an inability to adequately function in their daily lives without the emotional stability provided by nicotine consumption (Robinson et al., 2011).
Dependence or habit? Nicotine as a 'vice'[edit | edit source]
Despite a physiological basis for nicotine dependence, debate exists as to what extent repeated smoking behaviours constitute an addiction. Many smokers do not consider themselves 'addicted' and argue that addiction is an inaccurate term (Collins, Maguire, & O'Dell, 2002). Others theorise that, because of the positive dopaminergic neural reward elicited by smoking, it is an habitual behaviour, one that occurs automatically without awareness, rather than indicative of addiction (Robinson, & Pritchard, 1995).
Many smokers and researchers liken smoking to an 'emotional crutch' parallel to other individuals' daily consumption of coffee, tea, or chocolate in order to provide stimulation, focus, relaxation, or emotional stability in daily life (Collins, Maguire, & O'Dell, 2002; see also Nehlig, 2004).
|“||I knew a man who gave up smoking, drinking, sex, and rich food. He was healthy right up to the day he killed himself||”|
Nicotine, emotion, and other drugs[edit | edit source]
Recent research demonstrates that all presently listed personality disorders in the DSM share a strong association with dependency on, or abuse of other substances. This includes not only nicotine but also alcohol, cannabis and stimulants. Personality disorders are those which present long-term maladaptive emotions, cognitions and functioning (Hasin et al., 2011). Furthermore, individuals with an existing pathology may use combinations of substances to regulate their emotions.
Alcohol[edit | edit source]
As indicated by Kobiella (2010), nicotine can produce emotional blunting and hypersensitivity to unpleasant emotional stimuli for non-smokers. However, concurrent alcohol consumption is shown to counter possible blunting effects and instead hyper-sensitises the smoker to positive or pleasing emotional stimuli. Therefore the two are often used in combination (Dawkins & Powell, 2011). Braun et al. (2012) indicate that the combined consumption of alcohol and nicotine significantly reduces anxiety and inhibitions to a greater extent than what each drug provides individually.
Cannabis[edit | edit source]
Viveros, Marco and File (2006) argue that cannabis is increasingly used in combination with nicotine. Of particular concern is that although the cannabinoids in this combination can further reduce anxiety of users, it reinforces positive reward associations with nicotine. Consequently, nicotine addiction is more likely to be maintained and emotional dysregulation associated with nicotine withdrawal is more likely to occur.
Coffee[edit | edit source]
Coffee and cigarettes share a distinct cultural bond. Ancient cultural practice has for many years combined smoking with coffee consumption. In many European and Asian cultures, flavoured tobacco is smoked in a hookah after a meal with coffee (Halevy, 2011). Lane (1996) identifies that drinking coffee can serve as a cue to initiate smoking, however drinking increased amounts of coffee does not necessarily maintain 'chain smoking'. Additionally, Lane (1996) found that cigarettes do not appear to serve as a cue to initiate drinking coffee.
The 2003 film Coffee and Cigarettes by Jim Jarmusch is an ironic look at the paradoxical emotional vice-grip of smoking. In one particular scene, Tom Waits and Iggy Pop celebrate their quitting smoking over conversation, coffee and more cigarettes.
|“||[On Jim Jarmusch's Coffee and Cigarettes] It's me and Iggy Pop and basically what we had to do was sit around and drink coffee and smoke cigarettes. I started again. Got hooked. Terrible. But hey, it takes a man, right? It takes a real man to quit twice.||”|
Emotional effects of nicotine on adolescents[edit | edit source]
Social effects and peer pressure[edit | edit source]
Adolescence is a period of emotional turmoil, risk-taking and significant peer influence. Recent research suggests that peer pressure to engage in smoking is still relevant (Cavalca et al., 2013). However, other conflicting results suggest that alcohol may increasingly be the more appealing substance of choice over tobacco when in a peer pressure situation (Kiuru, Burk, Laursen, Salmela-Aro, & Nurmi, 2010). What these results both suggest is that peer influence still plays a significant role in adolescents' decisions.
The deliberation and subsequent choice whether to smoke is often fuelled by a cognitive dissonance or rationalisation that the behaviour is justified because ‘everybody else is doing it’ (Kleinjan, Eijnden, & Engels, 2009). Often when confronted with this dissonance, an adolescent may feel increased guilt, anxiety, hypersensitivity, and negative affect that their actions are betraying their own values or the values of their family (Cavalca et al., 2013).
Further influence and persuasion to uptake and maintain smoking can arise from the media. Although smoking is increasingly portrayed as a dirty and unhealthy habit, a significant cultural image nonetheless still exists that portrays smoking as fashionable or cool and associated with the tantalising appeal of risk-taking. In order to reduce or avoid the negative emotions associated with being 'uncool' adolescents may succumb to smoking (Shadel, Martino, Haviland, Setodji, & Primack, 2010).
Evidence for emotionally satisfying alternatives[edit | edit source]
E-cigarettes[edit | edit source]
E-cigarettes are an electronic, nicotine-free, product resembling a cigarette designed to aid individuals in quitting smoking. In support of the above habit-over-addiction theory, a study by Dawkins, Kent, and Turner (2010) found that those smokers who were using e-cigarettes experienced reduced withdrawal symptoms, reduced desire to smoke, and increased satisfaction after only 5 minutes of inhaling the vapour content. Therefore the nicotine content was not itself a central motivator to smoke, but rather it was the sequential habit of lighting and inhaling that provided a placebo effect enough to quell cravings and replace negative affect with reward in the short-term. The video advertisement above emphasises the guilt, discomfort and frustration associated with constant cravings.
Physical exercise[edit | edit source]
Before the innovation of e-cigarettes, research has shown for many years that vigorous exercise is another behaviour shown to produce acute short term reduction in negative affect, withdrawal symptoms and cravings, particularly for women. Additionally, vigorous exercise is particularly effective at helping preventing relapse in long-term attempts to quit smoking (Bock, Marcus, King, Borrelli, Roberts, 1999). The unusual video below emphasises the emotional and physical strain smoking causes for an individual trying to build muscle and maintain a fitness regime. The authors of the video further highlight that smoking is 'just a vice'.
(Warning: Contains coarse language)
Nicotine and performance[edit | edit source]
Despite the health reasons against smoking cigarettes, there is increasing evidence that suggests nicotine actually improves, in the short-term, higher cognitive processes. These effects may include improved attention, working memory, visual discrimination, spatial awareness and emotional regulation (Sahakian, Jones, Levy, Gray, & Warburton, 1989). This is consistent with the different reasons people give for smoking. Sometimes individuals will smoke to unwind from daily stress, and at other times individuals may smoke to mentally prepare or stimulate themselves for periods of increased focus. Nicotine affords the extra focus, clarity and stability to the individual in the same way a morning coffee peps you up or a hot chocolate calms you down, again reiterating the paradoxical effects of nicotine and providing insight into why this emotional crutch would be so difficult to give up. Could you make it through your morning work tasks without your vice?
Further evidence shows that nicotine improves cognitive deficits and behavioural inhibition for adolescents with ADHD. This is a stark contrast to the effects of alcohol that are shown to reduce behavioural inhibition and retard cognitive processes such as speech and memory (Potter & Newhouse, 2008).
These short-term improvements however are far outweighed by the catastrophic long-term health outcomes associated with nicotine and similar short-term benefits provided by fruit, vegetables and physical exercise such as yoga.
Emotional reactivity and environmental stimuli[edit | edit source]
The effects of regular nicotine consumption on one's emotions also extends to one's social environment and interactions. Research suggests that nicotine craving can be induced simply by exposure to people, places or stimuli the individual affiliates with smoking. For example, Conklin et al. (2013) indicate that socialising with regular smokers creates an emotional reactivity that compels the smoker to participate. By contrast, a smoker socialising with non-smokers generally will not feel the increased negative affect of cravings. Furthermore for smokers, simply observing an image of a cigarette lighter, or being in the same room where the individual has previously smoked can also serve as external cues to induce significant cravings. Therefore Conklin et al. (2013) suggest that developing strategies to manage ones social interactions and environment to avoid tempting scenarios can help toward smoking cessation and stronger intrinsic emotional control.
Look around you[edit | edit source]
When faced with the stress of daily life, maintaining a positive demeanour is not always simple. Kahler et al. (2012) conducted research examining a sample of low hostility (LH) and high hostility (HH) smokers and found that the HH participants showed delayed and reduced recognition of happy facial expressions. The researchers emphasise that these deficits can impact the degree to which HH smokers may recognise social approach and reward signals in the real world. So if you are a smoker and consider yourself as being easily aggressed or irritated, your smoking behaviours may predispose you to ignore the pleasant things going on around you and to only focus or ruminate on those situations, people, or gestures which are unpleasant.
For smokers however, smoking is still a valuable ruminative tool, despite it's ultimately damaging effects, when facing periods of significant emotional upheaval beyond the stress of daily life, such as grief or heartache (Hajek et al., 2010)
Short-term vs. Long-term effects of nicotine on emotion[edit | edit source]
Summary of short-term vs. long-term effects of nicotine on emotion and physiology
Conclusion[edit | edit source]
In conclusion, if you wish to improve your life, the healthiest option is to avoid smoking cigarettes. However, life is never that simple. It is important to consider the myriad personality variables and life events that precede and maintain an individual’s taking up smoking. These can include a person’s predisposition or sensitivity to stress and their emotional capacity or perceived ability to cope with stressful life events that are out of one’s control such as those that cause grief, pain, social pressure, humiliation, and anxiety.
Many smokers value smoking as their emotional crutch and fear losing or relinquishing control of this element of their life. Considering this, an important point to remember is that for many smokers, quitting the coffin nails is never as easy as just saying ‘no’. The individual must face significant physiological withdrawal symptoms, emotional instability, and societal pressure to smoke from peers and the media, as well as the ever-present threat of relapse. Therefore, before applying a fix-all solution to the problem, it is important to recognise how nicotine is influencing the individual’s emotions before intervening to break the circular smoking-stress link model. If cigarettes are instantly withdrawn cold turkey, negative affect increases. When negative affect increases, so do cravings and withdrawal symptoms.
Healthier options such as e-cigarettes or physical exercise provide alternative ways to generate dopaminergic reward, ease out of habitual behaviours and ultimately break addiction while hopefully experiencing increased positive emotion. It is hoped that the information within this chapter provides insight into the effects of nicotine on emotion that may be beneficial in improving your life and wellbeing.
See also[edit | edit source]
- Nicotine and Motivation
- Alcohol and Emotion
- Cannabis and Emotion
- Exercise and Emotion
- Behavioural Economics and Habit
- Daily Hassles and Uplifts
References[edit | edit source]
Balogopal, P., George, N., Venugopal, A., Mathew, A., Iqbal Ahamed, M., & Sebastian, P. (2012). Tobacco related habits among first degree patients undergoing surgery for advanced head and neck malignancies in India. Asian Pacific Journal of Cancer Prevention, 13, 217-22. doi:10.7314/APJCP.2012.13.1.217
Benowitz, N. (2010). Nicotine addiction. New England Journal of Medicine, 362(24), 2295-2303. doi:10.1056%2FNEJMra0809890
Bock, B., Marcus, B., King, T., Borrelli, B., & Roberts, M. (1999). Exercise effects on withdrawal and mood among women attempting smoking cessation. Addictive Behaviours, 24(3), 399-410. doi:10.1016/S0306-4603(98)00088-4
Braun, A., Heinz, A., Veilleux, J., Conrad, M., Weber, W., Wardle, M., …Kassel, J. (2012). The separate and combined effects of alcohol and nicotine on anticipatory anxiety: A multidimensional analysis. Addictive Behaviours, 37(4), 485-491. doi:10.1016/j.addbeh.2011.12.013
Cahill, K., Stead, L., & Lancaster, T. (2011). Nicotine receptor partial agonists for smoking cessation. The Cochrane Collaboration, 2, 2-4. USA: Wiley & Sons.
Carson, J. (Presenter), & Cordova, F. (Producer). (n.d.). The Tonight Show Starring Johnny Carson [Television series]. USA: NBC Studios.
Carton, S., Houezec, J., Lagrue, G., & Jouvent, R. (2000). Relationships between sensation seeking and emotional symptomatology during smoking cessation with nicotine patch therapy. Addictive Behaviours, 25(5), 653-662. doi:10.1016/S0306-4603(00)00067-8
Cavalca, E., Kong, G., Liss, T., Reynolds, E., Schepis, T., Lejuez, C., & Krishnan-Sarin, S. (2013). A preliminary experimental investigation of peer influence on risk-taking among adolescent smokers and non-smokers. Drug and Alcohol Dependence, 129(1), 163-166. doi:10.1016/j.drugalcdep.2012.09.020
Collins, P., Maguire, M., & O'Dell, L. (2002). Smokers’ representations of their own smoking: A Q-Methodological study. Journal of Health Psychology, 7(6), 641-652. doi:10.1177/1359105302007006868
Cook, S. A. (2007). “Liberation Sticks” or “Coffin Nails”? Representations of the working woman and cigarette smoking in Canada, 1919-1939. Canadian Bulletin of Medical History, 24(2), 367-401. Retrieved from http://www.cbmh.ca/index.php/cbmh/article/view/931/926
Dawkins, L., Kent, T., Turner, J. (2010). The Electronic Cigarette: Acute Effects on Mood and Craving. Retrieved from University of East London, School of Psychology, www.uel.ac.uk/psychology
Dawkins, L., & Powell, J. (2011). Effects of nicotine and alcohol on affective responses to emotionally toned film clips. Psychopharmacology, 216(2), 197-205. doi:10.1007/s00213-011-2197-4
Grant, R. (2004, October 08). Trailer-park troubadour. The Telegraph. Retrieved from http://www.telegraph.co.uk/culture/4730471/Trailer-park-troubadour.html
Halevy, A. (2011). The Infinite Emotions of Coffee. USA: Macchiatone Communications.
Hasin, D., Fenton, M., Skodol, A., Krueger, R., Keyes, K., Geier, T., …Grant, B. (2011). Personality Disorders and the 3-Year Course of Alcohol, Drug, and Nicotine Use Disorders. Arch Gen Psychiatry, 68(11), 1158-1167. doi: 10.1001/archgenpsychiatry.2011.136
Kahler, C., McHugh, R., Leventhal, A., Colby, S., Gwaltney, C., & Monti, P. (2012). High hostility among smokers predicts slower recognition of positive facial emotion. Personality and Individual Differences, 52(3), 444-448. doi:10.1016/j.paid.2011.11.009
Kiuru, N., Burk, W., Laursen, B., Salmela-Aro, K, & Nurmi, J. (2010). Pressure to drink but not to smoke: Disentangling selection and socialization in adolescent peer networks and peer groups. Journal of Adolescence,33(6), 801-812. doi:10.1016/j.adolescence.2010.07.006
Kleinjan, M., Eijnden, R., Engels, R. (2009). Adolescents' rationalizations to continue smoking: The role of disengagement beliefs and nicotine dependence in smoking cessation. Addictive Behaviours, 34(5), 440-445. doi:10.1016/j.addbeh.2008.12.010
Kobiella, A., Ulshöfer, D., Vollmert, C., Vollstädt-Klein, S., Bühler, M., Esslinger, C., & Smolka, M. (2010). Nicotine increases neural response to unpleasant stimuli and anxiety in non-smokers. Addiction Biology, 16(2), 285-295. doi:10.1111/j.1369-1600.2010.00237.x
Lane, J. (1996). Association of coffee drinking with cigarette smoking in the natural environment. Experimental and Clinical Psychopharmacology, 4(4), 409-412. doi:10.1037/1064-12184.108.40.2069
Musk, A., & DeClerk, N. (2003). History of tobacco and health. Respirology, 8, 286-290. doi:10.1046/j.1440-1843.2003.00483.x
Nehlig, A. (2004). Coffee, Tea, Chocolate and the Brain. USA: CRC Press.
NSW Government Health (2007). Nicotine and other poisons. Retrieved from http://www0.health.nsw.gov.au/factsheets/general/nicotine.html
Potter, A., & Newhouse, P. (2008). Acute nicotine improves cognitive deficits in young adults with attention-deficit/hyperactivity disorder. Pharmacology Biochemistry and Behaviour, 88(4), 407-417. doi:10.1016/j.pbb.2007.09.014
Robinson, J., & Pritchard, W. (1995). Differentiating habits and addictions: The evidence that nicotine is not addictive. Effects of Nicotine on Biological Systems II, 7(641), 273-278. Retrieved from http://link.springer.com/chapter/10.1007/978-3-0348-7445-8_35
Sahakian, B., Jones, G., Levy, R., Gray, J., & Warburton, D. (1989). The effects of nicotine on attention, information processing, and short-term memory in patients with dementia of the Alzheimer type. The British Journal of Psychiatry, 154(6), 797-800. doi:10.1192/bjp.154.6.797
Shadel, W., Martino, S., Haviland, A., Setodji, C., & Primack, B. (2010). Smoking motives in movies are important for understanding adolescent smoking: A preliminary investigation. Nicotine and Tobacco Research, 12(8), 850-854. doi:10.1093/ntr/ntq099
Ursprung, W., Savageau, J., & DiFranza, J. (2011). What is the significance of experiencing relaxation in response to the first use of nicotine? Addiction Research and Theory, 19(1), 14-21. doi:10.3109/16066359.2010.507892
Viveros, M., Marco, P., & File, S. (2006). Nicotine and cannabinoids: Parallels, contrasts and interactions. Neuroscience and Biobehavioural Reviews, 30(8), 1161-1181. doi:10.1016/j.neubiorev.2006.08.002
Weinberger, A., & Sofuoglu, M. (2009). Cognitive enhancement as a pharmacotherapy target for stimulant addiction. Addiction, 105(1), 38-48. doi:10.1111/j.1360-0443.2009.02791.x