The present study confirms the presence of a higher proportion of anxiety (approximately 37.1% for male and 45.7% for female) and depression (approximately 35.3%) in Greek outpatients with COPD than those in the general population. However, the lack of a control group may limit the generalisability of these results. The female population with COPD is differentiated from males by higher levels of anxiety and depressive symptoms. These findings are in accordance with previous studies that indicated a higher prevalence of overall anxiety and depressive symptoms among women with COPD [15, 36].
Independently of gender, there are many mechanisms that could be involved in this comorbidity. Patients with COPD have poor physical functioning, a condition which has been shown to be related to higher rate of psychological morbidity . The high levels of anxiety and depressive symptoms are possibly the result of pressure from social factors, as well as from coping with daily living. Many of these patients have had to limit their daily activities due to their lung disease. They frequently have to change jobs or retire early. Their social interactions are also adversely affected because they cannot maintain pace with their peers . In addition, patients with COPD soon realise that his/her disease is irreversible and progressive [14, 37]. Furthermore, the hypoxic nature of the disease and dyspnoea may lead to increased distress [36, 37].
However, an impressive finding of our study was that anxiety and depression were not correlated with COPD severity (as determined by FEV1 percentage of predicted). In a previous study  it was reported that dyspnoea ratings were influenced by anxiety and depressive symptoms, whereas the physiological state (including FEV1 percentage of predicted) scarcely influenced the anxiety and depressive symptomatology. Although further studies are required in order to explain these findings, it is possible that patients construe disease seriousness subjectively, which contributes to the development of the levels of anxiety and depressive symptoms.
The prevalence of alexithymia in COPD patients, contrary to what has been observed in patients with other chronic respiratory diseases, seems to be lower. However, a positive correlation was observed between alexithymia, anxiety and depressive symptoms. Previous studies based on both clinical and healthy populations have reported a connection between depressive symptomatology and alexithymia, and it is well known that patients with depressive disorders are prone to experiencing alexithymic features [39, 40]. Additionally, alexithymic features have been related to higher levels of anxiety . Due to the limitations of our study, we cannot answer the question of whether alexithymia leads to depressive and anxiety symptoms or depression and anxiety symptoms lead to alexithymia.
Compared with other psychosomatic and somatic diseases, such as bronchial asthma, the prevalence of alexithymia in COPD is lower. Furthermore, alexithymia may be related to recurrent very severe asthma exacerbations in asthmatics [42–44].
We did not study possible associations of COPD exacerbations with any of the other parameters studied. Thus, although we cannot support a similar hypothesis for COPD exacerbations, we believe that the correlations that were seen among alexithymia, depression and anxiety levels should be taken into consideration when drafting psychotherapeutic interventions (as a part of a pulmonary rehabilitation program) for these patients . This is more pertinent in those patients with overall alexithymic characteristics (who often fail to recognise their underlying psychological malaise due to a lack of capacity for mental representation of emotions) [46, 47]. These deficiencies may cause an inability to regulate emotions and affect and, therefore, may lead to increased somatisation and attenuated capacity to recognise the underlying depressive symptoms or anxiety (and lack thereof of therapeutic intervention) [44, 47]. Furthermore, subjects with high anxiety and depressive symptoms and concomitant alexithymia most probably have difficulty in verbally expressing their symptoms . In alexithymia, by definition, the difficulty in expressing psychological symptoms as such leads to their expression as somatic (often atypical) symptoms . The latter may distract clinicians and make them miss the psychological component that lies at the root of the problem. Given this, the possible presence of alexithymia should be taken into consideration when planning specialised psychotherapeutic interventions within respiratory rehabilitation programs.
Additionally, patients with severe depression and anxiety are less likely to be compliant to treatment plans and more likely to be hospitalised . Therefore, comprehensive programs should incorporate individualised depression and anxiety management techniques.
Finally, this study does have some limitations. First is the lack of a control group; second, we did not study possible associations of COPD exacerbations with any of the other parameters studied. These limitations should be taken into consideration in further work.