Smoking and panic disorder: severity and comorbidities

Abstracts

INTRODUÇÃO: Estudos indicam que há uma associação entre tabagismo e transtorno do pânico, e alguns autores sugerem que o tabagismo aumenta o risco de ataques de pânico e transtorno do pânico. Este estudo analisa a hipótese de que pacientes fumantes com esse transtorno apresentam um quadro clínico mais grave. MÉTODO: Sessenta e quatro pacientes em tratamento no Laboratório do Pânico e Respiração (Instituto de Psiquiatria da Universidade Federal do Rio de Janeiro), com transtorno do pânico, segundo critérios do Manual de Diagnóstico e Estatística das Perturbações Mentais (DSM, 4ª edição), foram divididos em grupos de tabagistas e não-tabagistas. Os grupos foram avaliados quanto a características sociodemográficas, comorbidades e gravidade do quadro clínico. RESULTADOS: Não houve diferença significativa em relação à gravidade do transtorno do pânico; no entanto, tabagistas tiveram prevalência de depressão significativamente maior (p = 0,014) do que não-tabagistas. CONCLUSÃO: Este estudo não evidenciou que o transtorno do pânico em tabagistas é mais grave, porém indicou que esses pacientes têm mais comorbidade com depressão.

Transtorno de pânico; agorafobia; tabagismo; transtorno depressivo

ORIGINAL ARTICLE

Smoking and panic disorder: severity and comorbidities

Rafael Christophe da Rocha Freire^I; Marco André Mezassalma^II; Alexandre Martins Valença^III; Valfrido Leão de-Melo-Neto^IV; Fabiana Leão Lopes^V; Isabella Nascimento^VI; Antônio Egidio Nardi^VII

^IPsychiatrist. MSc. student, Instituto de Psiquiatria, Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro, RJ, Brazil

^IIMSc. in Psychiatry. PhD student, Instituto de Psiquiatria, UFRJ, Brazil

^IIIPhD in Psychiatry. Associate professor, Department of Psychiatry, Universidade Federal Fluminense (UFF), Niterói, RJ, Brazil

^IVPsychiatrist. MSc. student, Instituto de Psiquiatria, UFRJ

^VPhD in Psychiatry. Researcher, Instituto de Psiquiatria, UFRJ, Brazil

^VIPhD in Psychiatry. Researcher, Instituto de Psiquiatria, UFRJ, Brazil

^VIIPhD in Psychiatry. Associate professor, Instituto de Psiquiatria, UFRJ, Brazil

^{Correspondence}

ABSTRACT

INTRODUCTION: Several studies indicate that panic disorder and tobacco smoking are associated, and some authors hypothesize that smoking increases the risk of panic attacks and panic disorder. The objective of this study is to investigate whether smokers have a more severe form of panic disorder than non-smokers.

METHOD: Sixty-four patients already in treatment at the Laboratory of Panic and Respiration (Instituto de Psiquiatria da Universidade Federal do Rio de Janeiro) with panic disorder as established by the Diagnostic and Statistical Manual of Mental Disorders, fourth edition, were divided into groups of smokers and non-smokers. Both groups were compared regarding sociodemographic data, comorbidities and clinical status severity..

RESULTS: There was no statistically significant difference between the two groups regarding severity; however, prevalence of depression was significantly higher in the smoker group than in non-smokers (p = 0.014).

CONCLUSION: This study did not indicate that smokers have a more severe form of panic disorder, but smoking and comorbid depression were associated.

Keywords: Panic disorder, agoraphobia, smoking, depressive disorder.

Introduction

Recent studies indicate that there is a high prevalence of smoking in patients with psychiatric disorders, such as schizophrenia, depression, bipolar disorder, panic disorder (PD), obsessive-compulsive disorder, posttraumatic stress disorder and attention-deficit/hyperactivity disorder.¹ This association was more studied in relation to anxiety disorders and, among them, panic attacks (PA) and PD seem to be more closely related to the smoking habit.^2,3 Epidemiological studies indicate that the prevalence of smoking in patients with PD is higher than that of the general population^4,5 and that, in most cases, smoking precedes occurrence of PD, suggesting that use of tobacco could be a risk factor for PA and PD.^4-9 On the other hand, other studies indicate that PD does not increase risk of smoking^5-7 and that PD symptoms possibly motivate people to quit smoking.⁴

In a study carried out in 2,032 Australian adolescents, there was higher risk of smoking in individuals whose peers smoked or had anxiety or depression symptoms.¹⁰ Two possible explanations for that association are that smoking and anxiety disorders share the same etiology; anxious individuals have a higher risk of smoking.¹⁰ Some authors raised the hypothesis that there is a group of smokers using nicotine to obtain sedation, and another using this substance due to its stimulating effect,¹¹ but more recent studies indicate that nicotine had stimulating and sedative effects in the same individuals.¹² Also, it was observed that, when use of cigarettes occurs simultaneously to a distracting stimulus, there is reduction in anxiety; however, in case such stimulus is not present, the level of anxiety is not significantly altered.¹³ Nicotine leads to increase in adrenergic activity, with increased heart rate, vasoconstriction, blood pressure and intestinal motility, and high doses could lead to PA.¹⁴ An epidemiological study conducted by Breslau & Klein,⁶ including 5,418 individuals, indicated that daily use of tobacco significantly increases risk of PA and PD.

Several studies showed that PD is related to abnormalities of the respiratory system^15-18 and that the smoking habit could be one of the mechanisms causing such abnormalities.^6-8 West & Hajek¹⁹ studied 101 smokers presenting criteria for nicotine dependence established by the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) and that interrupted use of cigarettes. They found increased anxiety soon after smoking cessation, and over a 4-week period there was gradual reduction in anxiety to lower levels than over the 2 weeks preceding smoking cessation.¹⁹ However, in the literature there are case reports of patients with PD that stopped smoking and, during the abstinence syndrome, had significant increase in PA.²⁰

Zvolensky²¹ studied the effect of smoking in patients with PD. In smokers there was a higher intensity of anxiety symptoms, more functional impairment and more clinical complications than in nonsmokers.²¹ The aim of this study is to confirm whether smokers have a more severe clinical status of PD. We expect to find more comorbid depression and agoraphobia, longer disease time and higher severity score in smoking patients.

Method

This study was conducted at Instituto de Psiquiatria (IPUB), Universidade Federal do Rio de Janeiro (UFRJ), Brazil. IPUB, which is a university psychiatric hospital part of the Brazilian Unified Health System, predominantly providing care to patients in the south area of Rio de Janeiro, but many patients come from other locations in the city, and these patients have varied socioeconomic and cultural levels. This was a cross-sectional study of patients with PD undergoing treatment at the Laboratory of Panic & Respiration of IPUB.

Sample

This study used a clinical convenience sample composed of 64 patients that, when assessed, were in PD acute stage, starting or undergoing psychiatric treatment for up to 6 months. Smokers and nonsmokers were given the same type of treatment. Diagnoses were performed using the Structured Clinical Interview Diagnostic for Axis I Disorders (SCID-I)²² for DSM-IV.²³ Inclusion criteria were age between 18-65 years and diagnosis of PD according to DSM-IV criteria. To maintain sample homogeneity, only patients that had at least three PA over the 2 weeks preceding the interview were included. Among individuals with major depression, dysthymia or generalized anxiety disorder, only those who had main diagnosis of PD were included in the study. Exclusion criteria were mental retardation, psychotic disorder, bipolar disorder and severe clinical disease (including severe asthma and severe chronic obstructive pulmonary disease). This study was approved by the research ethics committee of IPUB at UFRJ.

Sociodemographic and clinical data

The patients were interviewed by a psychiatrist and provided information regarding age, gender, schooling, family income in minimum wages and whether or not they were employed. They were also questioned as to duration time and age of disease onset, smoking habit and cases of first-degree relatives with PD. Patients who stopped smoking less than 1 year ago were considered smokers. The psychiatrist also assessed severity of clinical status during the interview, classifying it according to the Clinical Global Impressions Scale (CGI)²⁴ for each patient.

Statistical analysis

The sample was divided into two groups - smokers and nonsmokers - that were compared using Student's t test and chi-square. In tests in which the sample did not present normal distribution, Student's t test was replaced by Mann-Whitney rank sum test. Analysis was bidirectional and statistical significance was set in 0.05. SPSS 13.0 was used for statistical analysis.

RESULTS

Sample

In the investigated sample, mean age was 39.8 years (SD = 11.7); 46.9% (n = 30) were male and 53.1% (n = 34) were female. Schooling was classified as follows: 0 - up to incomplete school; 1 - complete school; 2 - incomplete high school; 3 - complete high school; 4 - complete higher education. Mean sample schooling level was 3.2 (SD = 1.4), which is equivalent to complete high school. Mean age of PD symptom onset was 31.8 years (SD = 9.8). Mean time between symptom onset and assessment was 96.9 months (SD = 101.2). Mean CGI score was 3.9 (SD = 1.3) (Table 1). Of the interviewees, 34.4% (n = 22) were smokers, and 35.3% (n = 12) of women and 33.3% (n = 10) of men smoked. Women had higher prevalence of comorbid depression (61.8%) than men (40%), but this difference was not statistically significant (chi-square = 3.023, 1 gl, p = 0.082).

Comparison between groups

There were no significant sociodemographic differences between smokers and nonsmokers. Differences in onset age and PD duration, family history, CGI and prevalence of agoraphobia were not significant when comparing both groups. The group of smokers had significantly higher prevalence of depression (chi-square = 6.013, 1 gl, p = 0.014) (Table 2, Figure 1).

Table 2- Click to enlarge

Discussion and conclusion

Prevalence of smoking in this sample in both genders was similar to that of the Brazilian population, in which 38% of men and 24% of women smoke.²⁵ However, in patients with PD, there was prevalence of smoking a little higher for women and a little lower for men than in the general population, which could be attributed to specific characteristics of patients with PD. Association between smoking and depression and increased prevalence of depression in women with PD could explain high prevalence of smoking in women of the studied sample.

Zvolensky et al.²¹ found that smokers with PD had more anxiety, more anticipatory anxiety in relation to PA and more PD severity, but there was no significant increase in frequency or intensity of PA in these patients. In this study, there was no statistically significant difference in PD severity when smokers and nonsmokers were compared.

Prevalence of agoraphobia was similar between smokers and nonsmokers, and there was a significant association between smoking and depression. In the study by Zvolensky et al.²¹ there were no differences as to agoraphobia, but depression scores and prevalence of depressive disorder were similar between both groups. There are reports of high incidence of smoking in patients with PD,^1-3,26 in patients with depression^1,26-31 and in patients with comorbid conditions,²⁶ but the association of PD with depression and smoking is a new finding. It is believed that nicotine causes reduction in negative affections, reduction in stress and increase in positive affections, which takes place through activation of nucleus accumbens and other dopaminergic nucleus involved in the reward system.³¹ Such positive effect of nicotine explains why people with depression have higher risk of smoking.³² On the other hand, abstinence to nicotine leads to increase in negative affections, depressed mood, nervousness, restlessness, irritability, anxiety, impatience, anger, aggressiveness, somnolence and feeling of fatigue.²⁸ For that reason, smokers with depression have more difficulty to quit smoking and have more recurrences in tobacco use.³¹

This study has a number of limitations, such as small sample size, patients in different treatment stages and assessment of severity using CGI only. Most researches on the association between PD and smoking use population and random samples, and this study used a clinical convenience sample with smaller size. Using a larger sample, other associations could possibly be shown, such as relation between smoking and pregnancy. All patients were in the acute stage of PD and were given the same treatment, but a few already had some improvement in symptoms, whereas others were still starting treatment, which might have influenced CGI scores. Scales used in other studies, such as Beck Anxiety Index,³³ Panic Disorder Severity Scale³⁴ and Sheehan Patient-Rated Anxiety Scale,³⁵ were not used in this study.

Patients with PD, smokers and nonsmokers, had very similar sociodemographic profiles and clinical characteristics. Results showed that diagnosis of comorbid PD with major depression was strongly associated with the smoking habit.

References

Received August 29, 2007.

Accepted October 2, 2007.

This study was performed at the Laboratory of Panic & Respiration, Instituto de Psiquiatria (IPUB), Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro, RJ, Brazil. This research was funded by the Brazilian Council for Scientific and Technological Development (CNPq).

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Publication Dates

• Publication in this collection
  31 Mar 2008
• Date of issue
  Dec 2007

History

• Received
  29 Aug 2007
• Accepted
  02 Oct 2007