The relation of testosterone levels with fatigue and apathy in Parkinson's disease.

Objective: Fatigue and apathy are frequent in patients with Parkinson's disease (PD). Testosterone deficiency in male patients may contribute in development of fatigue and apathy as well. We investigated whether a possible relation exists between serum testosterone levels, fatigue and apathy in male PD patients.
Materials and Methods: We included 29 non-demented and non-depressed PD patients and 30 age- and sex-matched healthy subjects. Fatigue Severity Scale (FSS) and Apathy Evaluation Scale (AES-C) were used for the evaluations. In PD patients and healthy subjects, a relationship between FSS, AES-C scores and plasma testosterone levels were assessed. In addition, a correlation between FSS, AES-C and Unified Parkinson's Disease Rating Scale was investigated in PD group.
Results: The mean scores of FSS and AES-C were significantly higher in PD patients than those of the control group. The Unified Parkinson's Disease Rating Scale (UPDRS) scores were significantly correlated with FSS and AES-C scores. Mean free testosterone level was significantly lower in PD patients than controls (p=0.008). f-Testosterone levels of PD patients were not correlated with FSS or AES-C scores.
Conclusion: Apathy and fatigue are frequent in PD and show significant correlation with the severity of the disease. f-Testosterone levels are not related with apathy or fatigue in male PD patients and the role of testosterone in the pathophysiology of these non-motor symptoms is still controversial.