The concepts of fatigue and depression in cancer

Abstract

A strong association between fatigue and depression in cancer patients has been reported repeatedly in clinical studies. The distinction remains difficult, mainly because of the similar phenomenology of fatigue and depression. It is the aim of this paper to work out similarities and differences in the conception of fatigue and depressive disorders. For that, a differentiation between depression as emotional distress and depression as clinical syndrome, according to the current classification systems, has to be made. Therefore, the classification of depressive disorders and their criteria is presented in the second section of this paper, especially in view of the diagnosis of depressive disorders in cancer patients. The comparison of the multidimensional fatigue construct and depression shows a strong overlap of symptoms. None of the fatigue symptoms are specific for fatigue, all being elements of depressive syndromes. It is in particular the psychological symptoms of depressive disorders that differentiate between the two concepts. To that end, the question is discussed whether fatigue in its current conceptualization can be defined as a diagnostic entity independent of depressive disorders. Additionally, research approaches are presented from the area of the chronic fatigue syndrome and neurasthenia, which could be adapted to cancer-related fatigue and help to clarify the clinical differences between fatigue and depression. In order to ensure better differential diagnostics in the future, criteria-orientated research in particular is needed.

Fatigue in breast cancer survivors two to five years post diagnosis: a HEAL Study report

“…This relationship is complex and not well understood [55]. Fatigue is a symptom of depression; chronic fatigue can produce depression, and in some cases, fatigue and depression share a common etiology.…”

Depression and hopelessness in Turkish patients with cancer undergoing chemotherapy

“…Montazeri et al (2000) reported that anxiety and depression in patients with cancer reduced in time with the help of supportive care. Various studies showed that the prevalence of depression in patients with cancer increased due to the adverse effects of chemotherapy (Reuter & Harter, 2004;Loftis & Hauser, 2005). Musselman et al (2001), in their study on 43 female patients with cancer, found that the rate of major depression development among the patients constantly receiving high doses of interferon was~50%; in the study of Farrell et al, anxiety and depression were indicated in 24% of the patients.…”

Fatigue in Cancer Survivors – Prevalence and Correlates

“…Disease-and treatment-related factors as well as further physical symptoms had no impact on the severity of fatigue in any of its dimensions. The results indicate that chronic fatigue is determined by physical and psychological factors rather than by the prior cancer itself or its treatment.Thisisinlinewithfindingsofseveralotherstudies.The strongestpredictoroffatigueisdepression.Thecoincidence of fatigue and depression has often been shown [14,17,23,24].Associationsbetweenfatigueanddepressionarecomplex and,untiltoday,noevidencehasbeenfoundforacauseand effectrelationship.Itmightbeaskedwhetherdepressionand fatigue are the same phenomenon, as some authors assume [23].Ourresultsindicatethatfatigueisnotacompleteequivalentofdepression,eventhoughwepostulateaconsiderable overlap.Depressionasasingularfactordoesnotsatisfactorily explainfatigue.…”

“…Psychological factors, in particular depressed mood, seem to be among the strongest correlates of fatigue [8][9][10][11][12]. Other psychologicalfactors,includinganxiety [12][13][14],havebeendescribedaswell.Mixedevidencewasfoundforanassociation withsleepdifficulties [10,[15][16][17][18].Theimpactofsocio-demographicvariableslikeage,sex,educationlevel,maritalstatus, employment status, and income is controversial, whereas the majority of studies negated a relationship between them [14,17,18].Onlyafewstudiesfounda(mostlyweak)effectofage [4,5,9,11],gender [4,8],ormaritalstatus [8,19].Theresults arefarmorecontradictoryconcerningdisease-andtreatmentrelatedfactors.Somestudiesreportedarelationshipbetween fatigueandstageofdisease [4,12],treatment [9,14],timesince diagnosis [20],cancersite [15,20],andhormonaltreatment [14,18,20].Othershavenotrevealedanyassociation [5,10,13,17,18,[21][22][23]. Among the physical factors considered, pain was oftenfoundtocorrelatewithfatigue [9,…”