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In this month’s issue (pp 1260–4 and 1323–6) there are two papers that each address different aspects of wellbeing in patients with Parkinson’s disease.1,2 Their similarity lies in the fact that both relate to aspects of human sexual systems and function. The study by Castelli et al finds small improvements in the sexual wellbeing of men with Parkinson’s disease following therapeutic subthalamic nucleus stimulation.1 The study by Ready et al2 draws our attention to a relationship between feelings of apathy and low serum testosterone levels in men with Parkinson’s disease.2
Although these studies deal with methodologically difficult areas—and as such their conclusions must be treated with caution—they do serve to raise the awareness of practising neurologists to important aspects of their patients’ feelings of wellbeing.
The paper by Castelli and colleagues is the first to systematically evaluate sexual function in Parkinson’s disease patients following subthalamic stimulation.1 The effects demonstrated are small, yet positive. Given that subthalamic nucleus stimulation reduced dopamine requirement in their patients and that there is some evidence that dopaminergic medication produces an increase in sex drive, one might suppose that the effects of subthalamic nucleus stimulation are mediated through very complex processes—including an overall improvement in body image as a result of a successful neurosurgical intervention. Disappointingly, no improvements in sexual functioning were demonstrable in women with Parkinson’s disease following subthalamic nucleus stimulation.
In a busy general or movement disorder clinic there is little time to explore patients’ feelings of self worth, feelings of attractiveness, and drive (including sex drive). Rather, the question concerning sexual potency when asked of men is often little more than a way of screening for the 10–15% of our Parkinson’s disease patients who may in fact be suffering from multiple system atrophy. However, it is very common to hear complaints from our patients—often mediated via their spouse and frequently via the Parkinson’s disease nurse specialist—that since developing Parkinson’s disease they feel apathetic and lack drive and interest in sex even though they are still potent. These feelings, of course, may reflect commonly overlooked co-existent depressive illness, but as pointed out by Ready and colleagues they can exist independently of depression and seem, unlike depression, to correlate with testosterone deficiency.2
Ready et al report that nearly 50% of the men with Parkinson’s disease studied are testosterone deficient.2 Notwithstanding some difficulties with defining a “normal” testosterone level and our lack of understanding why patients with Parkinson’s disease may be apparently testosterone deficient, the idea that dopamine and testosterone deficiencies act as comorbidities—which combine in susceptible patients to reduce frontal lobe system functioning leading to reduced libido, sexual dysfunction, fatigue, mood change, and apathy—is important. Testosterone deficiency is easily reversed and any potential for future treatment to improve some of these very significant non-motor symptoms of Parkinson’s disease is to be welcomed.
These two papers will encourage neurologists looking after patients with Parkinson’s disease to make themselves even more aware of their patients’ overall feelings of wellbeing—including their sexual wellbeing. They encourage us to explore new ways of improving Parkinson’s disease patients’ wellbeing through psychological, physical, endocrine, pharmacological, and surgical interventions.