Smoking is not a mental illness

The joke when I was a medical student was that a doctor would never give a diagnosis of alcoholism unless the patient drank more than the doctor. I am reminded of this joke when I consider the American Psychiatric Association’s (APA’s) definition of alcoholism [1]. It describes alcoholics who drink you under the table, go on benders (staying drunk for days on end), are often too hungover to go to work and who get arrested for drunken behavior. The APA’s definition describes such flagrant alcoholics that there must have been some devoted drinkers on the definitions committee. Although the APA’s definition of alcoholism is not particularly helpful in the early detection of an impending drinking problem, alcohol researchers should appreciate their good fortune to have a definition of their own. Nicotine researchers could not get an original definition of nicotine dependence; we were forced to use a second-hand definition of alcoholism. Woody Allen complained about having to wear his cousin’s hand-me-downs: “She was not my size”. Likewise, the definition of alcoholism was a poor fit when it was applied to nicotine in the Third Edition of the APA’s Diagnostic and Statistical Manual of Mental Disorders[2]. Since nicotine is not intoxicating, smokers do not learn to hold their nicotine, they do not go on smoking benders and they do not miss work due to a smoking hangover or get pulled over for driving under the influence of nicotine. Nevertheless, smoking researchers had to make do as the APA defined nicotine dependence as a mental illness characterized by a ‘maladaptive pattern of behavior’ [1].

In the proper course of medical science, doctors discover a disease and study enough cases to describe its clinical manifestations and pathophysiology. Diagnostic criteria should be based on real cases. This never happened with nicotine dependence because, instead of studying smokers, the APA studied alcoholics. As the APA adopted a ‘one-size-fits-all’ approach to the diagnosis of drug dependence, changes made over the years to the APA definition of nicotine dependence were intended to bring it in line with evolving views on alcoholism [3]. Therefore, the nicotine-dependent ‘mental disorder’ that the APA’s diagnostic criteria describe does not derive from an understanding of the natural disease process. It judges smokers’ behavior against a cultural standard regarding what behaviors are maladaptive. For example, spending a lot of time smoking is a criterion for the mental illness of nicotine dependence. Are avid golfers mentally ill because they spend a lot of time golfing? Another sign of this mental illness is continued smoking despite the presence of a condition that is made worse by smoking. I think of all the asthmatics that do not evict their cats; are they mentally ill? Although the APA definition of nicotine dependence as a mental illness is a cultural standard, and just a redressed definition of alcoholism at that, it was quickly accepted as the scientific ‘gold standard’, partly because of the APA’s stature and partly because nicotine researchers were hungry for the validation and funding that would come when nicotine was recognized as a real drug, just like alcohol.

The APA envisioned nicotine dependence to be a psychiatric behavioral disorder that could be accompanied by a physiological component [1]. Researchers imagined that peer pressure kept youths smoking for years [4]. Smokers were thought to become psychologically dependent on the pleasure of smoking and, according to the APA, ‘within a few years of daily smoking, smokers note withdrawal symptoms’ [5]. Since researchers were already convinced that non-daily smokers could not experience withdrawal, they did not bother to ask them if they did or not. According to the APA ‘within a few years of daily smoking, most smokers begin to develop dependence’ [5]. Since researchers were told that nicotine dependence was acquired over years, it made no sense to ask novice smokers about symptoms of dependence. By describing regular use as a prerequisite for nicotine dependence, the APA’s alcohol-based disease definition blinded researchers to the real thing.

Reminiscent of the child who observed that the king had no clothes, the folly of the APA’s approach of defining criteria for a disease without studying it first was revealed when a teenage girl told me that she had been smoking for less than 2 months and had already failed in repeated attempts to quit. Another girl told me that she smoked one or two cigarettes, 3–4 days per week and could not quit smoking. After smoking a cigarette, she would feel normal for approximately 2 days but then she would develop an intense craving for a cigarette, irritability and impatience. Smoking a cigarette restored her to normal for a few more days. Our research team has completed over 19,000 interviews with adolescents and we have surveys from approximately 100,000 more [6–9]. The data reveal that everything the authors of the APA’s definition imagined about the onset of nicotine dependence was wrong.

As it turns out, the first two girls I interviewed were quite typical of novice smokers. By far, the month following the first cigarette is the most likely time for nicotine dependence to begin [6]. Here I am not using the APA’s definition of nicotine dependence. I am using the term dependence as it is used by just about anyone who is not a member of the APA, meaning that the person is ‘hooked’. Like a fish on a hook, a person is hooked when escaping from smoking requires an effort or causes the person to suffer [10]. True believers in the APA’s definition have protested that being hooked is not the same thing as meeting the APA diagnostic criteria. That is exactly my point. When we are not blinded by fixed ideas about the nature of dependence and we study smokers instead of alcoholics, we get to see and describe the real disease.

What we see is that it is common for a youth to be hooked after smoking just one cigarette [9]. Half of young smokers are hooked by the time they have smoked a pack of 20 cigarettes and 93% by the time they have smoked 100 or more cigarettes [9]. Most kids have symptoms of addiction long before smoking becomes a habit and before they learn to depend on smoking to cope with stress.

As with the first two girls I interviewed, novice smokers develop classic nicotine withdrawal symptoms when they are smoking only a few cigarettes per month [11]. These individuals report that smoking a single cigarette can suppress withdrawal for many days, perhaps weeks at a time. They are able to forgo smoking for several days or weeks with no difficulty, but once the withdrawal symptoms appear the craving is intense. Adult ‘social smokers’ have also described this same experience of obtaining complete relief from withdrawal from a single cigarette, only to have intense craving re-emerge after a few days [12].

We now understand from case histories obtained from youths and adults that the duration of relief that smokers can obtain from smoking a single cigarette shrinks over time. The strength of the craving seems to bear no relation to how much one smokes. Adult nondaily smokers sometimes report that their cravings are ‘unbearable’ [12]. As tolerance to the withdrawal-suppressing effect of nicotine grows, intense cravings force the individual to smoke at more frequent intervals [13]. If we were to continue the fishing metaphor, when the fish is first firmly hooked it has plenty of line to play with and considerable freedom of movement, but over time, the line gets shorter and shorter. A novice smoker in her thirties reassured me that she was not hooked because she only smoked one cigarette per week, when she got a craving. The cravings initially come so widely spaced that smokers do not recognize them as signs of addiction. That epiphany usually occurs when the smoker realizes that he or she needs a cigarette every day, and that is usually when the first failed attempt at cessation occurs. However, many young individuals also fail in their attempts to quit prior to the onset of daily smoking, sometimes when they are smoking only a few cigarettes per month.

As the interval between cravings becomes shorter and shorter, the smoker smokes more and more frequently. Because the smoker is hooked, he or she may eventually spend a lot of time smoking as described in the APA’s diagnostic criteria. However, smokers are not dependent because they spend a lot of time smoking; they spend a lot of time smoking as a consequence of being dependent. As a consequence of breaking a leg, a person may miss work and use crutches, but we do not use missing work and using crutches as criteria to diagnose a broken leg. The APA’s diagnostic criteria do not describe dependence; they describe some of the behaviors that smokers display as a consequence of being dependent. This is a crucial difference. We would never examine the crutches to learn what causes bones to break, yet people do look to the APA’s criteria for insight into the nature of dependence.

To most nonsmokers, the idea that addiction could begin with the first cigarette seems implausible. But one cigarette delivers enough nicotine to occupy 88% of the nicotinic acetylcholine receptors in the human brain [14]. One dose of nicotine is enough to trigger molecular remodeling in the brain, as evidenced by an upregulation in the number of high-affinity nicotinic acetylcholine receptors [15]. One dose stimulates noradrenaline synthesis in the hippocampus of rats for at least 1 month [16]. So smokers could feel the impact of nicotine for weeks after one cigarette. One dose is all it takes to trigger behavioral sensitization in rats [17]. Behavioral sensitization to nicotine is evidenced by increased locomotor activity in response to the second dose compared with the first. However, locomotor sensitization is not just a learned or conditioned effect, subsequent doses of nicotine cause more widespread and intense neural activation, as measured by functional MRI [18]. In animal models, nicotine withdrawal is triggered after just a few doses of nicotine [19]. Given the evidence of rapid and extensive neurophysiological changes that occur in the brain very soon after the first dose, it seems unlikely that the highly neuroplastic brains of children and adolescents would be impervious to these effects.

What is entirely implausible is the thought that it takes many years of regular smoking to trigger addiction [5]. I am aware of no animal studies that have demonstrated a long-delayed impact of nicotine. Consider this: each cigarette delivers ten puffs, ten bolus doses of nicotine. The APA contends that dependence begins within a few years of daily smoking. If a person smoked five cigarettes per day for 2 years, that would be 36,500 doses. How many medications do we prescribe that take 36,500 doses to begin to work? None that I can think of.

When the APA laid claim to nicotine dependence in 1980 by proclaiming it to be a mental illness [2], it did so without ever studying a single case of the onset of nicotine dependence. It defined dependence in terms of social obligations and conceptualized dependence as a socially maladaptive behavior. Those in the field of psychology or psychiatry usually envision nicotine dependence as the product of maladaptive learning produced by classical behavioral mechanisms, such as conditioning and reinforcement [20]. In their view, nicotine dependence is above all a psychological disorder that may at times be accompanied by signs of ‘physical dependence’ [1]. In my view, smoking does have a psychological component. Smokers can become convinced that they cannot cope with stress without a cigarette; they believe that giving up smoking is like losing a friend and find the prospect of never smoking again to be frightening. Ironically, the APA’s criteria for nicotine dependence do not include any of these psychological symptoms.

The basic science literature demonstrates that brief, intermittent doses of nicotine trigger a variety of short- and long-term changes to brain chemistry and functioning. Case histories reveal that many smokers experience symptoms of nicotine dependence soon after the initiation of intermittent smoking. The convergence of clinical and laboratory evidence suggests that nicotine dependence is a disorder of neurophysiology. It is a neurological condition that is characterized by an insatiable hunger for nicotine. As one 16-year-old patient noted, after smoking just a few cigarettes you develop a “need” to smoke and then “you have to smoke to feel normal again.” Like hunger or thirst, the acquired need for nicotine is driven by neurological mechanisms. These mechanisms do not take years to develop, they develop overnight. Approximately a quarter of novice smokers report a craving for nicotine after just a few cigarettes [9]. Nicotine dependence does involve learning; smokers must learn to cope with an insatiable hunger for nicotine. They must adapt their behavior to satisfy the brain’s demand for nicotine. Unfortunately, the behavior that satisfies the demand for nicotine is often maladaptive when it comes to social obligations or remaining healthy. Coping with an insatiable hunger for nicotine can lead to psychological symptoms, such as a fear of a life without nicotine. But the roots of nicotine dependence lie in neurophysiology not psychology. Just as stroke victims must adapt their behaviors to cope with their neurological limitations, smokers’ behave as they must to deal with their neurological condition. In my opinion, nicotine dependence is most appropriately viewed as a neurological condition, not a mental illness.

Financial & competing interests disclosure

The author has no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.

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