Studies found that both depressed and anxious non-asthmatic patients had higher levels of C-reactive protein (CRP), interleukin (lL)-6, tumour necrosis factor-alpha (TNF-α), interferon-gamma (IFN-Υ) than healthy controls [41,42] and depressive symptom-associated IL-1β and TNF-α release correlated with impaired bronchodilator response and neutrophilic airway inflammation in asthma [43,44]. Here, TNF is linked to asthma.