Does asymmetric dimethylarginine play a role in depression in chronic kidney disease patients?: FIGURE 1:

Depression is a pervasive disorder involving mood, thought and body function. It causes discomfort and moral pain to the depressed person and his/her family and close social contacts. This disorder manifests by a series of symptoms that alter sleep, eating habits, work capacity and the ability to enjoy pleasant life activities. Depression may be a sporadic phenomenon but it usually recurs during lifetime. Without appropriate treatment, a depressive episode may last for years and may not resolve. Importantly, depression is a proteiform condition and may occur within the context of other chronic illnesses such as heart disease or chronic kidney disease (CKD) where it stands as the most frequent mental problem [1]. A recent meta-analysis carried out on 55 982 CKD patients showed that about one-quarter of such patients are depressed. The prevalence of depression increases in parallel with the severity of CKD [2] and may depend on the type of substitutive treatment in patients with end-stage renal disease [3]. It is associated with poor outcomes in dialysis patients, and depressive symptoms predict a higher risk of mortality and cardiovascular events [4] as well as an increased risk of hospitalization [5]. This association is also true in pre-dialysis CKD patients where the presence of depression predicts progression to kidney failure, hospitalization or death independently of age, race, serum haemoglobin, albumin, phosphorus, comorbidities and kidney disease severity [6]. Overall these studies suggest that depression should not be considered as a mere surrogate of other CKD comorbidities and that it may be an independent risk factor for adverse clinical outcomes in these patients. Behavioural factors such as non-adherence to medical treatment, poor nutrition, unhealthy life style and lack of social interactions [7, 8] as well as biological factors including genetic background [9], inflammation and impaired immune status [10] may concur to explain the association between depression and adverse outcomes in this population.