Background: Depression is a particular problem in older people and it is important to know how it affects and is affected by smoking cessation. Aims: To identify reciprocal, longitudinal relationships between smoking cessation and depression among older smokers. Methods: Across four waves, covering six years (2002–2008), changes in smoking status and depression, measured using the 8–item Centre for Epidemiologic Studies Depression Scale, were assessed among recent ex-smokers and smokers (N=2,375) in the English Longitudinal Study of Ageing. Results: In latent growth curve analysis, smoking at baseline predicted depression caseness longitudinally and vice versa. When both processes were modelled concurrently, depression predicted continued smoking longitudinally (B(β)=0.21 (0.27); 95%CI 0.08,0.35) but not the other way around. This was the case irrespective of mental health history and adjusting for a range of covariates. Conclusions: In older smokers, depression appears to act as an important barrier to quitting while quitting has no long-term impact on depression
