**2. Prevalence of smoking in mental illness**

Recent literature has noted the significant numbers of smokers suffering from mental illnesses and the relationship between smoking and mental disorders [9]. Furthermore, many studies have reported that the prevalence of smoking is two to three times higher in patients with mental illness than in non-smokers. Consequently, the prevalence of smoking has disproportionately affected people with mental health issues [10, 11]. This prevalence is rising significantly among people with mental health problems, from 18% for people without mental health problems to 61% for people with issues [11]. Besides this, the prevalence of smoking in people with mental illness can range from 50 to 85%, and they are much less likely to quit smoking compared to the general population [1]. The prevalence increases with the severity of mental health issues [12]. In the United Kingdom, an estimated 30% of smokers have a mental disorder and more than 40% of cigarette smokers have a severe mental illness [13]. Likewise, people with mental health and substance abuse issues also have a high prevalence of smoking of approximately 30–35% [14]. A report from the Royal College highlighted that around 30% of smokers or 10% of all smokers have experienced a mental illness that is currently being treated with psychotic medication in the UK [6]. Furthermore, smokers with mental disorders are more vulnerable in low socioeconomic communities; for instance, around 48% of smokers with mental illnesses are low socioeconomic disadvantages while 33% of those mental health conditions are moderate or high socioeconomic class [11].

Many countries have made remarkable progress in tobacco control and have implemented a variety of policy measures to control smoking habits which have resulted in a reduction in the prevalence of smoking over the last few decades,

#### *Smoking and the Association with Mental Health DOI: http://dx.doi.org/10.5772/intechopen.104233*

particularly in the European Countries and the United States [15]. However, the smoking rates in Asian countries did not reveal any sign of improvement [10]. Some of these developed countries have identified that individuals with mental illness have a substantial rate of smoking [16]. Despite the decrease in the prevalence of smoking in the general population in Western Nations, it is insignificant in people with good mental health, hence there has been an increase in the difference in the prevalence of smoking among people with mental illnesses and the general population [15]. A number of studies have revealed that the proportion of smokers without mental illness declined from about 20% to around 15%, while the smoking rate of adults with a mental health condition remains stable at around 29% [11, 15]. In the US, one in five people has a mental illness and half of this population is cigarette smokers which results in 40% of the annual deaths among those with mental illnesses are related to tobacco use [17]. Similarly, a high smoking rate in people with mental health problems has a major toll on death and health status in the US, whereas around 200,000 of the annual 443,000 premature deaths are estimated to occur in these populations [14]. Recent evidence also highlighted that an individual with chronic mental illness dies on average 25 years earlier than members of the general population [14]. This vulnerable population consumes 44% of all cigarettes, which reflects the high prevalence and heavy smoking habits in the United States; likewise, a similar estimate of consumption has been projected for in the UK, Australia, and New Zealand [11, 14].

Unfortunately, recent evidence indicates that smokers are more likely to be diagnosed with mental health conditions, including schizophrenia, bipolar disorder, psychosis, depression, and anxiety disorder than non-smokers and the highest rate of tobacco use are among patients in psychiatric departments where up to 70 and 50% of these patients are heavy smokers [3, 5]. Some studies indicated that tobacco use is significantly more prevalent in people with schizophrenia than the general population and smokers with schizophrenia tend to have a heavy habit, as well as shorter life expectancies [3, 11, 18]. The prevalence of smoking in patients with schizophrenia accounts for around 70 to 80%, whilst different studies have demonstrated that the current prevalence of smoking in individuals with schizophrenia is from 64 to 72% versus 19 to 29% in people who are mentally healthy respectively [19, 20].

Likewise, the prevalence of current smoking among people with bipolar disorder (BD) is estimated to be in the region of 30 to 70% [3]. Although some data can be attributed to small and non-representative groups with regard to smoking prevalence, other studies with larger sample sizes produce different findings; For instance, data taken earlier by the National Comorbidity Survey (NCS) indicated that smoking prevalence in BD was 69%, whereas recent data from the National Health Interview Survey (NHIS) revealed a smoking rate of 46% [3]. Despite the difference in this prevalence depending on countries, clinical studies and populations have consistently indicated that the smoking prevalence is approximately two to three times higher in people with BD than in the general population [3, 19, 21]. However, higher smoking prevalence in people with bipolar disorder contributes to both early onset of smoking and a reduced success rate in smoking cessation.

Furthermore, a recent strong epidemiological study has revealed the relationship between smoking and depression, hence tobacco-smoking individuals with depression have a higher prevalence than the normal population [22]. The estimated smoking prevalence among patients with major depression or those with clinically remarkable depressive symptoms ranges from 40 to 60%, thus the smoking rate is


**Table 1.**

*This table illustrates the prevalence of smoking both daily smoking and heavy smokers as well as the rate of smoking cessation in mental illness patients.*

double among individuals with depression [22]. Similarly, many studies have pointed out the link between smoking and depression and the prevalence of major depression have been noted to be from 22 to 60% among smokers [23]. Other studies with different sample sizes demonstrated that the smoking prevalence in those with severe mental illness were observed to be around 74% for schizophrenics, 66% for BD, and 57% for major depression (**Table 1**) [12, 24, 25].
