Inflammatory markers associated with COPD–depression link
medwireNews: Two studies reported this week show that levels of pro-inflammatory cytokines are associated with both pulmonary function and depressive symptoms.
The findings suggest that systemic inflammation in chronic obstructive pulmonary disease (COPD) could explain why depression is so common among people with the condition.
"Pro-inflammatory immune alterations involving central and systemic responses may be the common underlying process explaining why patients with asthma and COPD commonly present with multiple medical co-morbidities, including depression, cardiovascular disorders, diabetes, [and] obesity…" say Tze Pin Ng (National University of Singapore) and colleagues, the authors of one of the studies, published in Respiratory Research.
Their research, which involved 2077 adults aged 55 years and over (mean: 66.3 years), found that people with high levels of serum interleukin (IL)-6 (above median 2 pg/mL) were 61% more likely to have five or more depressive symptoms according to the Geriatric Depression Scale than those with low serum IL-6 levels (7.1 vs 4.5%), while depressive symptoms were 49% more likely in those with high levels of C-reactive protein (CRP; above median 9.65 g/dL) than those with low levels of CRP (6.2 vs 4.3%).
Furthermore, depressive symptoms and high levels of serum IL-6 and CRP were each independently associated with lower forced expiratory volume in 1 second (FEV1) % predicted, and FEV1/forced vital capacity % predicted, after adjusting for confounders.
"These results therefore suggest that measures of pro-inflammatory immune markers and depressive symptoms could serve as a clinically useful index in assessing and subtyping individuals for risks of obstructive pulmonary disorders," say the authors.
Similar findings were reported at the American Thoracic Society International Conference in Philadelphia, Pennsylvania, from a study of 450 tobacco-exposed COPD patients. In the 86 patients with a Beck Depression Inventory (BDI) score of 10 or more, IL-6 levels were significantly higher, at 2.4 pg/mL, than in patients with lower BDI scores, at 1.8 pg/mL.
And regression analyses showed that low FEV1 % predicted correlated most strongly with increased depressive symptoms, followed by female gender, current smoking status, and increased IL-6.
"Our findings add evidence of a strong relationship between depression and one of the hallmarks of COPD, systemic inflammation, independent of the severity of disease," commented author Hilary Strollo (University of Pittsburgh, Pennsylvania) in a press statement.
"The assessment and treatment of depression should be part of the routine care of COPD patients," she concluded.
medwireNews (www.medwirenews.com) is an independent clinical news service provided by Springer Healthcare Limited. © Springer Healthcare Ltd; 2013
By Kirsty Oswald, medwireNews Reporter