Pharmacological interventions for daytime sleepiness and sleep disorders in Parkinson's disease: Systematic review and meta-analysis.

BACKGROUND: Daytime sleepiness and sleep disorders are frequently reported in Parkinson's disease (PD). However, their impact on quality of life has been underestimated and few clinical trials have been performed. OBJECTIVES: We aimed to assess the efficacy and safety of pharmacological interventions for daytime sleepiness and sleep disorders in PD. METHODS: Systematic review of randomized controlled trials comparing any pharmacological intervention with no intervention or placebo for the treatment of daytime sleepiness and sleep problems in PD patients. RESULTS: Ten studies (n = 338 patients) were included. Four trials addressed interventions for excessive daytime sleepiness. Meta-analysis of the three trials evaluating modafinil showed a significant reduction in sleepiness, as assessed by the Epworth Sleepiness Scale (ESS) (- 2.24 points, 95% CI - 3.90 to - 0.57, p < 0.05). In one study, treatment with caffeine was associated with a non-significant improvement of 1.71 points in ESS (95% CI, - 3.57 to 0.13). The six remaining trials assessed interventions for insomnia and REM sleep Behaviour Disorder (RBD). Single study results suggest that doxepin and YXQN granules might be efficacious, while pergolide may be deleterious for insomnia and that rivastigmine may be used to treat RBD in PD patients. However, there is insufficient evidence to support or refute the efficacy of any of these interventions. No relevant side effects were reported. CONCLUSIONS: Whilst providing recommendations, this systematic review depicts the lack of a body of evidence regarding the treatment of sleep disorders in PD patients; hence, further studies are warranted.

Challenges and promises in the development of neurotrophic factor-based therapies for Parkinson's disease.

Parkinson's disease (PD) is a chronic movement disorder typically coupled to progressive degeneration of dopaminergic neurons in the substantia nigra (SN). The treatments currently available are satisfactory for symptomatic management, but the efficacy tends to decrease as neuronal loss progresses. Neurotrophic factors (NTFs) are endogenous proteins known to promote neuronal survival, even in degenerating states. Therefore, the use of these factors is regarded as a possible therapeutic approach, which would aim to prevent PD or to even restore homeostasis in neurodegenerative disorders. Intriguingly, although favorable results in in vitro and in vivo models of the disease were attained, clinical trials using these molecules have failed to demonstrate a clear therapeutic benefit. Therefore, the development of animal models that more closely reproduce the mechanisms known to underlie PD-related neurodegeneration would be a major step towards improving the capacity to predict the clinical usefulness of a given NTF-based approach in the experimental setting. Moreover, some adjustments to the design of clinical trials ought to be considered, which include recruiting patients in the initial stages of the disease, improving the efficacy of the delivery methods, and combining synergetic NTFs or adding NTF-boosting drugs to the already available pharmacological approaches. Despite the drawbacks on the road to the use of NTFs as pharmacological tools for PD, very relevant achievements have been reached. In this article, we review the current status of the potential relevance of NTFs for treating PD, taking into consideration experimental evidence, human observational studies, and data from clinical trials.