Overlap and common correlates between depression and COPD: a narrative review

Background: Chronic obstructive pulmonary disease (COPD) is characterized by a burden of comorbid conditions, including depression, that has been related with an increased risk of exacerbations, low adherence to pharmacological treatments and behavioral interventions, and overall mortality rates. The aim of the present review was to explore the comorbidity between depression and COPD by examining epidemiological and etiopathogenetic perspectives, along with shared risk factors including the potential role of hypoxia, systemic inflammation, and drugs for COPD treatment. Methods: the aim of this work was to review studies published in the last eleven years, using Medline/PubMed, Scopus, and Google Scholar as search engines and the following terms “Mood Disorders", "Hypoxia "Pulmonary Disease, Chronic Obstructive", “Chronic obstructive pulmonary disease”, linked by the Boolean operator “AND”. Articles were included in the review if written in English and containing quantitative and qualitative information on Depression, Chronic Obstructive Pulmonary Disease, and Hypoxia. Exclusion criteria were studies in languages other than English, irrelevant articles to the examined topic reviews, case reports, case series, and articles on animal models. Results: The present review has confirmed the increased risk of depression onset in COPD patients, suggesting a strong multifactorial and bidirectional correlation between the two conditions. Hypoxia has been emphasized as a key mechanism in both diseases, whereas evidence on shared inflammatory and molecular pathways is still limited. Conclusions: The multifactorial nature of the bidirectional correlation between COPD and depression is far from being entirely understood. Comorbid depression negatively affects COPD course and severity, along with patients’ functioning, psychological well-being and quality of life. Well-designed pre-clinical and clinical studies on the genetic, molecular, and neurobiological pathways which underlie the comorbidity between COPD and depression are needed for addressing the clinical implications and treatment options. needs more research efforts to be clarified. Further studies are mandatory to improve our knowledge on the co-presence of these two widespread diseases.