Depression can be a difficult subject to talk about, but it is important to be aware of the increased prevalence of depression in people with cystic fibrosis and other chronic health conditions, and to try to understand how depression, physical health, and general well-being are interrelated.
In 2007, five doctors and scientists at Johns Hopkins University and the University of Chicago investigated the relationship between lung function (FEV1), depression, and health-related quality of life (HRQoL) among adults with CF.
To assess health-related quality of life, they used the Cystic Fibrosis Questionnaire, which looks at physical functioning, vitality, health perceptions, respiratory symptoms, treatment burden, role functioning, emotional functioning, and social functioning.
Seventy-six adults with CF participated in the study, and 30% (23 people) were positive for depressive symptoms. About two-thirds of the 23 people were in the mild-to-moderate range, and about one-third had moderate-to-severe depression.
Analysis of the HRQoL Cystic Fibrosis Questionnaire, the Beck Depression Inventory and the participants’ FEV1 levels yielded the following conclusions:
- People with lower FEV1 tended to have more depressive symptoms.
- When levels of FEV1 were segmented, people with more depressive symptoms had lower HCQoL than others in the same FEV1 segment.
- People with more depressive symptoms and lower FEV1 reported significantly worse HCQoL in all categories than people of any FEV1 without depressive symptoms.
These findings are fairly intuitive, but also interesting because HCQoL covers respiratory symptoms – meaning that according to this study, people with more depression and lower Fev1 have worse respiratory symptoms than people with the same FEV1 and no depression. Because this is correlation, I believe it is possible to ask whether the depression causes the worse respiratory symptoms in people of the same FEV1, or if worse respiratory symptoms (exacerbation rate) causes depression in people of the same FEV1.
Certainly, the correlations found in the study indicate that treating depression is an important component of CF care, especially because depression affects around 30% of the adult CF population. See this comprehensive analysis of the Prevalence and Impact of Depression in Cystic Fibrosis, which looks at children, adults and caregivers.