Cigarette Smoking by Patients With Serious Mental Illness, 1999–2016: An Increasing Disparity

Participants were individuals with a diagnosis of schizophrenia or bipolar disorder or without a diagnosed psychiatric disorder who were enrolled during the period January 1999 to November 2016 in the Stanley Research Program at Sheppard Pratt Health System in Baltimore for a study of the association between infection, immunity, and psychiatric disorders. All participants provided written informed consent after the study procedures were explained. The study was approved by the Sheppard Pratt Institutional Review Board.

The inclusion criterion for individuals with schizophrenia was a diagnosis of schizophrenia, schizophreniform disorder, or schizoaffective disorder. The inclusion criterion for individuals with bipolar disorder was a diagnosis of bipolar disorder, including bipolar I disorder, bipolar II disorder, or bipolar disorder not otherwise specified. The participants with psychiatric disorders were recruited from inpatient and day hospital programs of Sheppard Pratt and from affiliated psychiatric rehabilitation programs. The diagnosis of each of these participants was established by the research team, which included a board-certified psychiatrist, and was based on the Structured Clinical Interview for DSM-IV Axis I Disorders (27) and available medical records.

The inclusion criterion for the participants without a psychiatric disorder (control group) was the absence of a current or past psychiatric disorder as determined by screening with the DSM-IV Axis I Disorders, Nonpatient Edition (28). These persons were recruited from posted announcements at health facilities and universities in the same geographic area where the psychiatric participants were recruited.

Participants in all groups met the following additional criteria: age 18–65 (except for the control group, for which ages ranged from 20 to 60), proficient in English, absence of any lifetime history of intravenous substance abuse, absence of intellectual disability by history, absence of HIV infection, absence of a serious medical disorder that would affect cognitive functioning, and absence of a current primary diagnosis of alcohol or drug abuse or dependence per DSM-IV criteria. Participants were not selected on the basis of their smoking status.

As part of the background interview, each participant was asked, “Are you a current cigarette smoker?” And if yes, “How many packs per day do you smoke?” If the participant was on a smoke-free hospital unit, responses were based on his or her preadmission smoking. Each participant’s smoking status was assessed at one time point (study enrollment). All participants were also asked about demographic variables, including maternal education as a proxy for family socioeconomic status (29), and were assessed on a cognitive battery, the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) (30). All participants with psychiatric disorders were evaluated on the Positive and Negative Syndrome Scale (31) and were categorized as to their history of alcohol or drug abuse or dependence (apart from caffeine). Medications received at the time of study enrollment for participants with psychiatric disorders were recorded.

We found markedly elevated rates of smoking among individuals with schizophrenia and bipolar disorder over the past 18 years compared with participants with no psychiatric disorders. An average of 62% of those with schizophrenia and 37% with bipolar disorder identified themselves as cigarette smokers. By contrast, only 17% of the participants without a psychiatric disorder (control group) were current smokers. The prevalence of smoking in the sample as a whole decreased significantly over the study period, consistent with trends in the general U.S. population (1); however, the decrease was largely attributable to the control group. The prevalence of smoking in the two diagnostic subgroups in our study is generally consistent with reports in the literature, but data about smoking in psychiatric populations during the most recent five-year period are limited (2).

In our study, compared with the control group, participants with schizophrenia were more than three times as likely and those with bipolar disorder more than twice as likely to smoke, after adjustment for year of enrollment and demographic variables. The lack of significant time trends in the groups with psychiatric diagnoses is consistent with the results of our previous study and also with those of a study based on national data that covered a period through 2011 (10,25). The reasons for this lack of progress are multifactorial and may include limited treatment for smoking in psychiatric settings. This lack of progress has occurred against a background of calls to action by psychiatric leaders and organizations (14,16,32), research studies showing that treatments for smoking cessation are effective and well tolerated among persons with schizophrenia and bipolar disorder (18–22), and new CMS guidelines that provide incentives to hospitals for offering smoking cessation treatment to all patients (23). One can conclude that the myths about smoking and mental illness, articulated by Prochaska in 2011 (33), may remain prevalent. These include the misbelief that patients with mental illness need to smoke to cope with their symptoms, that quitting smoking leads to symptom exacerbation, that patients are not interested in quitting, and that they cannot quit—all of which have been found to lack supporting evidence.

The reasons that persons with schizophrenia and bipolar disorder are so much more likely to be smokers than those in the general population are not known with certainty, although a number of possible explanations have been offered in addition to the myths noted above. One suggested reason is that there may be an overlap in the genes associated with the risk for schizophrenia and with nicotine dependence; however, the genetic overlap is relatively small (34,35). In addition, randomized clinical trials have failed to show a consistent benefit in schizophrenia from medications that alter the function of nicotinic acid receptors (36,37). Another possible explanation is that patients derive special benefits from smoking in terms of ameliorating cognitive or psychiatric symptoms; however, the evidence here is also lacking (38,39). Another explanation, recently proposed, is that smoking is itself a risk factor for schizophrenia; the evidence to support this theory is incomplete (40,41). Social factors have also been cited as explanatory, including that smoking provides an opportunity for social interaction, that psychiatric settings tolerate smoking, and that patients with serious mental illness may be shielded from some of the stigma and public health messages about smoking (42). Many of these reasons may also account for low rates of quitting.

One encouraging finding is that smokers in our sample showed a statistically significant decline in the amount of cigarettes consumed over the 18-year study period. As an example of this trend, in 1999, the first year of data collection, 39% of participants with schizophrenia who smoked reported smoking more than a pack a day, but by 2016 that percentage was only 4%. It is not clear why the quantity of cigarettes consumed by smokers has declined, but the decline may be related to increased taxation on cigarettes and to state and local laws enacted during the study period that restrict smoking in public places. However, although smoking fewer cigarettes confers some harm reduction, only quitting altogether offers substantial health benefits (43).

Another encouraging finding is that persons under 30 in our sample were significantly less likely to be cigarette smokers than their older counterparts. This finding is consistent with another recent investigation of persons with serious mental illness that found that younger age was associated with less cigarette dependence (26). The other demographic and clinical correlates of smoking that we found are generally consistent with previous studies of persons with mental illness and the general population: lower education, male gender (1,44), a history of substance abuse or dependence (45), and Caucasian race (46); however, the correlation between Caucasian race and smoking was not found for the U.S. overall population (1).

The study had some limitations. Data through time were represented by different samples at each year, rather than by following the same participants over the study period. In addition, we did not collect information about participants’ smoking history, and thus we do not know the percentage of persons in each group who were previous smokers and who successfully quit. We also had only limited follow-up data about the smoking status of persons after they were assessed at the single time point. The small sample size by year in each group should also be noted. In addition, we did not collect data systematically about other nicotine products, such as e-cigarettes. Our sampling frame remained fairly constant over the study years, but research participants and those from intensive treatment programs tend not to be fully representative of patients overall. The schizophrenia group was disproportionately male compared with the other groups, and this may have inflated the prevalence of smoking in this group. Also, our enrollment of patients with schizophrenia began earlier than for the other groups, which may have affected group comparisons. Strengths of the study included the relatively large number of well-characterized participants studied over an 18-year period from the same set of treatment settings, and the unbiased collection of data about smoking.

The prevalence of smoking has remained alarmingly high among individuals with schizophrenia and bipolar disorder in our studies, and the disparity with participants without psychiatric disorders and with the general population is increasing. Additional measures are urgently needed to address this major public health problem.