Testosterone improves motor function in Parkinson's disease

In Parkinson's disease (PD) there is increasing evidence that sex steroids such as estradiol and testosterone modulate, either as a positive or negative effect, the clinical expression of a variety of movement disorders involving the nigrostriatum. Testosterone deficiency is common in the older male population and has an increased prevalence in parkinsonian patients. Testosterone therapy has been shown to improve the non-motor symptoms of PD but evidence for a direct effect of testosterone on motor symptoms is lacking. This case report demonstrates a significant improvement in the resting tremor and fine motor control after testosterone administration in a parkinsonian patient with testosterone deficiency (1 nmol/L). Motor symptom change was shown by serial assessment of the patient's handwriting, self-reporting using the Unified Parkinson's Disease Rating Scale and measurement of resting tremor amplitude by an accelerometer. The improvement in motor symptoms correlated with serum testosterone levels. The use of testosterone replacement in those men with decreased levels may improve the motor symptoms as well as increase general wellbeing.