Mental health problems, obstructive lung disease and lung function: Findings from the general population

Abstract

Objective

There is cumulative evidence for a strong association of obstructive lung disease, i.e. asthma and COPD, with poor mental health, particularly with anxiety disorders and major depression. However, studies relating mental health problems to objective measures of lung function as assessed by spirometry are lacking.

Methods

The 12-month prevalence of specific psychopathological syndromes among 1772 adults from the general population was estimated by a structured interview. Additionally, participants underwent spirometry and were asked about obstructive lung disease in the year prior to the study. Logistic and linear regression models were used to relate obstructive lung disease and spirometrically defined airway obstruction to mental health problems.

Results

Mental health problems were found in 35.7% of the participants. After adjusted for sociodemographic, clinical and life-style factors, asthma and chronic bronchitis were associated with almost all domains of mental health problems. In contrast, independent of its definition, spirometric airflow limitation was only related to generalized anxiety (odds ratios ranging from 2.3 to 2.7). A reduced ratio of forced expiratory volume in one second to forced vital capacity was associated with mental health problems in general and panic and general anxiety in particular.

Conclusion

Our findings suggest an association of objective measure of airflow limitation to generalized anxiety and panic. While the causal relationship between obstructive lung disease, airflow limitation and anxiety remains to be determined, clinicians should pay diagnostic attention to the significant overlap of these conditions.

Introduction

Cumulative evidence indicates a close association of obstructive lung diseases including asthma, chronic bronchitis and emphysema with mental health problems such as depression and anxiety [1], [2], [3], [4], [5]. Previous studies conducted among adult clinical and general practice samples have found higher-than-expected rates of anxiety and mood disorders, particularly major depression [6], [7], [8], [9], [10], [11], [12], [13]. The general validity of the relationship between asthma, chronic obstructive pulmonary disease (COPD) and mental disorders has been confirmed and extended by community-based studies [3], [14], [15], [16], [17], [18], [19], [20]. For instance, in a large cross-national study [3] including 18 population surveys from developed and developing countries, the pooled estimates of age- and sex-adjusted odds of mental disorders among persons with asthma relative to those without asthma ranged between 1.3 (social phobia) and 1.7 (dysthymia, panic disorder and alcohol-related disorders). A most recent survey even suggested a dose–response relationship between poor mental health and asthma severity [15]. Likewise, adults of the general population suffering from COPD had an increased risk of major depression and anxiety disorders compared to those without COPD with odds ranging from 1.9 to 3.8 [20].

Despite the valuable contributions of prior research and the consistency of findings, several methodological limitations leave important questions unanswered. These limitations include self-reported mental health problems [15], the use of self-report questionnaires to assess psychological distress [6], [7], [14], limited age range of participants [6], [17] or the exclusive focus on specific mental disorders [6], [11], [14], [19]. Furthermore, the confounding effects of socioeconomic status and smoking was not accounted for in all instances [15], [20], [21], [22], [23]. Finally, some studies failed to establish the diagnoses of asthma and COPD, respectively, by a physician, but relied on self-reported pulmonary conditions or diagnoses [3], [15], [19], [20]. Considering that perception of respiratory symptoms is often inaccurate and strongly influenced by affective states [24], [25], [26], findings may be influenced by self-report bias. There is only one general population study directly relating mental health to lung function as assessed by spirometry [27]. Persons with airflow limitation as defined by a fixed ratio of forced expiratory volume in one second (FEV1) to forced vital capacity (FVC) below 70% reported lower scores on the General Well-Being scale than participants with normal lung function [27]. However, this scale measures subjective psychological well-being, but not psychopathology. Furthermore, obstructive lung function was assumed in case the FEV1/FVC ratio was less than 70% [27]; however, the definition of airflow limitation is currently under intense debate and several operationalizations have been proposed [28]. Taking these considerations into account the objectives of our study were threefold: (i) to investigate the relationship of asthma and chronic bronchitis to mental health problems controlling for sociodemographic and behavioural factors in a general population sample, (ii) to relate mental health to different spirometric definitions of airflow limitation, and (iii) to determine the associations of mental health problems with physiologic measures of lung function independent of other determinants.