The relationship of fatigue to mental and physical health in a community sample

Background Previous studies have shown fatigue and depression/anxiety to be highly associated with each other. The present study seeks to differentiate between fatigue and depression/anxiety and to investigate the familiality/heritability of fatigue using sibpairs. Method The GENESiS study is a questionnaire study based in the United Kingdom that includes a fiveitem fatigue scale and four mental health measures (GHQ-12,EPQ-N,MASQ-AA,MASQ-HPA).Fatigue data from 10,444 sibling pairs were analysed using multivariate methods and model fitting techniques to investigate the familiality/heritability of fatigue and its relationship with the other mental health measures and physical health items. Results Fatigue correlated highly with GHQ-12 (r=0.62, p<0.001). A principal components analysis of the fatigue scale and the GHQ-12 revealed one main component which correlated highly with mental health items, and a smaller second component which correlated modestly with physical health items. Fatigue showed a modest sibling correlation (0.09, p<0.001), and multivariate modelling revealed evidence for familial effects on fatigue that were independent of the mental health measures. Conclusions Fatigue showed a strong relationship with both physical illness and mental health measures. Fatigue is modestly familial and at least part of this familial factor is not shared with mental health measures.