Depressive symptoms and all-cause mortality in people with type 2 diabetes: a focus on potential mechanisms.

BACKGROUND Depression has been associated with increased all-cause mortality in people with type 2 diabetes. AIMS To test whether anhedonia, dysphoria and anxiety are differentially associated with all-cause mortality and examine symptom-specific behavioural or pathophysiological mechanisms. METHOD A total of 1465 people completed the Edinburgh Postnatal Depression Scale in 2005 and were followed until death or 31 December 2010. Cox regression analyses compared survival time for people with a low v. high baseline dysphoria/anhedonia/anxiety score and identified mediating mechanisms. RESULTS After a mean follow-up of 1878 days (s.d. = 306), 139 participants had died. At all time points, people with anhedonia had an almost twofold increased mortality risk compared with those without anhedonia. Physical activity met criteria for mediation. Symptoms of dysphoria and anxiety were not associated with survival time. CONCLUSIONS Symptoms of anhedonia predicted shorter survival time, whereas dysphoria/anxiety did not. Mechanistic pathways, in particular physical activity, should be explored further.