Objective This review focuses on the possible association between restless legs syndrome (RLS) and movement disorders, including Parkinson disease (PD), other parkinsonian syndromes, essential tremor, choreic and dystonic syndromes, Tourette syndrome, and heredodegenerative ataxias. Methods Review of PubMed from 1966 to September 2018 and identification of references of interest for the topic. A meta-analysis of eligible studies on the frequency of RLS in patients with PD and controls using Meta-DiSc1.1.1 software and using the PRISMA guidelines was performed. Results and conclusions Although there are substantial clinical, neuroimaging, neuropathologic, and genetic differences between RLS and PD, many reports describe a higher than expected prevalence of RLS in patients with PD, when compared with the general population or with matched control groups; several studies have also suggested that RLS could be an early clinical feature of PD. RLS symptoms are frequent in multiple system atrophy, essential tremor, Tourette syndrome, Friedreich ataxia, and spinocerebellar ataxia type 3 as well. Finally, possible genetic links between PD and RLS (the presence of allele 2 of the complex microsatellite repeat Rep1 within the α-synuclein gene promoter) and between Tourette syndrome and RLS (several variants in the BTBD9 gene) have been reported in 2 case–control association studies, although these data, based on preliminary data with small sample sizes, need to be replicated in further studies.

Background: In the substantia nigra of Parkinson's disease (PD) patients, increased lipid peroxidation, decreased activities of the mitochondrial complex I of the respiratory chain, catalase and glutathione-peroxidase, and decreased levels of reduced glutathione have been reported. These observations suggest that oxidative stress and mitochondrial dysfunction play a role in the neurodegeneration in PD. We assessed enzymatic activities of respiratory chain and other enzymes involved in oxidative processes in skin fibroblasts cultures of patients with PD. Methods: We studied respiratory chain enzyme activities, activities of total, Cu/Zn- and Mn-superoxide-dismutase, gluthatione-peroxidase and catalase, and coenzyme Q10 levels in skin fibroblasts cultures from 20 Parkinson's disease (PD) patients and 19 age- and sex- matched healthy controls. Results: When compared with controls, PD patients showed significantly lower specific activities for complex V (both corrected by citrate synthase activity and protein concentrations). Oxidized, reduced and total coenzyme Q10 levels (both corrected by citrate synthase and protein concentrations), and activities of total, Cu/Zn- and Mn-superoxide-dismutase, gluthatione-peroxidase and catalase, did not differ significantly between PD-patients and control groups. Values for enzyme activities in the PD group did not correlate with age at onset, duration, scores of the Unified Parkinson's Disease Rating scales and Hoehn-Yahr staging. Conclusions: The main result of this study was the decreased activity of complex V in PD patients. This complex synthesizes ATP from ADP using an electrochemical gradient generated by complexes I-IV. These results suggest decreased energetic metabolism in fibroblasts of patients with PD.