It is recognised that patients who achieve clinical remission experience improvements in their depression and anxiety symptoms.21 This may be due to reduction in pain and fatigue levels from control of RA disease activity or it may be directly attributable to a reduction in pro-inflammatory cytokines including TNF-α, which can modulate neurotransmitter systems.34 It is possible that consent bias resulted in the inclusion of ‘happier’ patients, who are less likely to suffer from mental health disorder. Here, TNF is linked to major depressive disorder.