New clinical trials for nonmotor manifestations of Parkinson's disease

Nonmotor manifestations in Parkinson's disease (PD) encompass a range of clinical features, including neuropsychiatric problems, autonomic dysfunction, sleep disorders, fatigue, and pain. Despite their importance for patients' quality of life, the evidence base for their treatment is relatively sparse. Nevertheless, the last few years have seen a number of new trials starting that specifically address nonmotor features as an outcome measure in clinical trials. Large randomized, controlled trials in the last 3 years reported improvement of psychosis with the new selective serotonin 5-HT2A inverse agonist pimavanserin and of postural hypotension with the oral norepinephrine precursor droxidopa. Smaller new randomized, controlled trials support the effectiveness of Deep Brain Stimulation and opiates for pain, of rivastigmine for apathy and piribedil for apathy post-DBS, group cognitive behavioral therapy for depression and/or anxiety, continuous positive airway pressure for sleep apnea in PD and doxepin for insomnia, and of solifenacin succinate and transcutaneous tibial nerve stimulation for urinary symptoms. A number of new smaller or open trials as well as post-hoc analyses of randomized, controlled trials have suggested usefulness of other treatments, and new randomized, controlled trials are currently ongoing.