Fatigue after traumatic brain injury: Association with neuroendocrine, sleep, depression and other factors

Objective: Define associations between post-traumatic brain injury (TBI) fatigue and abnormalities in neuroendocrine axes, sleep, mood, cognition and physical functioning. Design: Survey. Setting: Large community hospital-based rehabilitation centre. Participants: Convenience sample of 119 individuals at least 1 year post-TBI. Outcome measures: Multidimensional Assessment of Fatigue (MAF); Fatigue Severity Scale (FSS); neuroendocrine assessments-growth hormone (GH) reserve, thyroid, cortisol and testosterone levels; visual analogue pain rating; Pittsburgh Sleep Quality Index; Beck Depression Inventory-II; Disability Rating Scale; Craig Handicap Assessment and Reporting Technique; Neurobehavioural Functioning Inventory. Results: Fifty-three per cent reported fatigue on the MAF and one-third on the FSS; 65% were found to have moderate/severe GH deficiency; 64% had adrenal insufficiency (low fasting cortisol); 12% had central hypothyroidism; and 15% of men had testosterone deficiency. Pituitary dysfunction did not correlate with fatigue or other symptoms. Predictors of MAF total scores were female gender, depression, pain and self-assessed memory deficits. Predictors of FSS scores were depression, self-assessed motor deficits and anti-depressant usage. Conclusions: Robust correlates of fatigue were gender, depression, pain and memory and motor dysfunction. Investigation of post-TBI fatigue should include screening for depression, pain and sleep disturbance. There was no correlation between pituitary dysfunction and fatigue; however, the relatively high prevalence of hypothyroidism and adrenal dysfunction suggests screening for these hormone deficiencies.