Many patients with Parkinson disease (PD) suffer from nonmotor symptoms including depression, anxiety, sexual dysfunction, decreased energy level, and an overall decline in quality of life. Comorbid depression, hypothyroidism, and sleep disorders may account for some, but not all, of these problems. Testosterone deficiency affects 20% to 25% of males over the age of 60 years in the general population and may cause signs and symptoms of the nonmotor symptoms seen in PD. We observed numerous patients with PD whose nonmotor symptoms were refractory to treatment.
To determine whether treatment of comorbid testosterone deficiency in male patients with PD can lead to improvements in refractory nonmotor symptoms.
Case studies were reviewed of the first 5 male patients who had PD with symptoms of testosterone deficiency who were treated in our clinic. All patients had low serum testosterone levels. Screening for testosterone deficiency symptoms using the St Louis Testosterone Deficiency Questionnaire was performed for 4 of the 5 patients. Additionally, to assess the prevalence of PD, total testosterone levels in 68 patients in our PD registry were sent for evaluation.
Following testosterone replacement therapy, all 5 patients experienced significant improvements in their refractory nonmotor symptoms. Of 68 male patients with PD enrolled in our PD registry, 24 (35%) had plasma evidence of testosterone deficiency. We also noted that the risk of testosterone deficiency per decade was found to increase 2.8-fold per decade (P<.001), paralleling that which is found in the general elderly male population.
The findings from this study reveal the heretofore unrecognized high prevalence of testosterone deficiency in elderly male patients with PD similar to that found in the general population. These symptoms, which may be refractory to antidepressants, anxiolytics, and antiparkinsonian medications, may respond to treatment with testosterone. More rigorous controlled studies will need to be undertaken to examine the treatment of this common comorbidity in male patients with PD.