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Parkinson's disease (PD) is a progressive neurodegenerative disorder. Genetic modifiers, environmental factors and gene-environment interactions have been found to modify PD risk and disease progression. The objective of this study was to evaluate the association of smoking, caffeine and anti-inflammatory drugs with age at onset (AAO) in a large PD cohort. A total of 35,963 American patients with idiopathic PD (iPD) from the Fox Insight Study responded to health and lifestyle questionnaires. We compared the median AAO between different groups using the non-parametric Mann-Whitney U test. Non-parametric Spearman's correlation was used for correlation assessments and regression analysis was used to assess interaction between variables. We found that smoking (p < 0.0001), coffee drinking (p < 0.0001) and aspirin intake (p < 0.0001) show an exploratory association with AAO in PD, that was further supported by multivariate regression models. The association of aspirin with PD AAO was replicated in another cohort (EPIPARK) (n = 237 patients with PD)., (© 2022. The Author(s).)

Comorbidity of psychiatric disorders in patients with movement disorders is common. Often, psychiatric symptoms manifest before the onset of the movement disorder, thus not representing a mere reaction to its burden. How the disease mechanisms of psychiatric and movement disorders are related is still poorly understood. The aim of the present study was to compare prevalence rates of specific psychiatric disorders between different movement disorders including isolated focal dystonia (IFD, N = 91), monogenic Parkinson's disease (PD, N = 41), idiopathic PD (N = 45), and a sample from a Northern Germany general population (TACOS Study; N = 4075). Our results indicate an odds ratio (OR) of 2.6 [confidence interval (CI) 1.7-4.0] for general axis I disorders in IFD, an OR of 2.5 (CI 1.4-4.7) in monogenic PD, and an OR of 1.4 (CI 0.8-2.6) in idiopathic PD. More specifically, the monogenic PD group showed the highest ORs for affective disorders including depression (OR = 4.9), bipolar disorder (OR = 17.4), and hypomanic episodes (OR = 17.0), whereas IFD expressed the highest rates of anxiety disorders (OR = 3.3). Psychotic symptoms were only observed in the PD groups but not in IFD. Our findings underline the notion that psychiatric disorders are part of the phenotypic spectrum of movement disorders. Moreover, they suggest that IFD, monogenic PD, and idiopathic PD are associated with specific psychiatric disorders indicating disturbances in a different neural circuitry for sensorimotor control.

DYTCA is a syndrome that is characterized by predominant dystonia and mild cerebellar ataxia. We examined two affected siblings with healthy, consanguineous, Turkish parents. Both patients presented with a combination of childhood-onset cerebellar ataxia, dystonia, and sensory axonal neuropathy. In the brother, dystonic features were most pronounced in the legs, while his sister developed torticollis. Routine diagnostic investigations excluded known genetic causes. Biochemical analyses revealed a mitochondrial respiratory chain complex IV and a coenzyme Q10 deficiency in a muscle biopsy. By exome sequencing, we identified a homozygous missense mutation (c.154A >C; p.Thr52Pro) in both patients in exon 2 of the COX20 (FAM36A) gene, which encodes a complex IV assembly factor. This variant was confirmed by Sanger sequencing, was heterozygous in both parents, and was absent from 427 healthy controls. The exact same mutation was recently reported in a patient with ataxia and muscle hypotonia. Among 128 early-onset dystonia and/or ataxia patients, we did not detect any other patient with a COX20 mutation. cDNA sequencing and semi-quantitative analysis were performed in fibroblasts from one of our homozygous mutation carriers and six controls. In addition to the exchange of an amino acid, the mutation led to a shift in splicing. In conclusion, we extend the phenotypic spectrum of a recently identified mutation in COX20 to a recessively inherited, early-onset dystonia-ataxia syndrome that is characterized by reduced complex IV activity. Further, we confirm a pathogenic role of this mutation in cerebellar ataxia, but this mutation seems to be a rather rare cause.

Objectives: This study aims to further evaluate the impact of family history of primary movement disorders (FHpMD) and a candidate genetic variant on risk of antipsychotic-induced extrapyramidal symptoms (EPS)., Methods: We examined 156 (76 men) inpatients receiving antipsychotics for EPS and FHpMD stratified by patient characteristics. The genetic analysis included genotyping of a multiallelic dinucleotide polymorphism in the ATP1A3 gene., Results: EPS lifetime prevalence was 69% and more frequent in the presence of FHpMD (p = 0.052), particularly in patients younger than 60 years (p = 0.012) and with acute dystonic reactions. The ATP1A3 polymorphism showed an allele length-dependent association with parkinsonism (p=0.019 uncorrected, p=0.057 corrected) exclusively. Carriers of the shortest allele had a 7.7-fold increased risk for parkinsonism., Conclusions: The association of FHpMD and EPS may be linked to the EPS subtype and age of the patient. A common ATP1A3 genomic variation may represent a susceptibility factor for the risk for antipsychotic-induced parkinsonism in an allele-dependent manner.

The multidrug resistance protein 1 (MDR1 or ABCB1) gene encodes a P-glycoprotein that protects the brain against neurotoxicants. Certain MDR1 genetic variants are known to compromise the function of this transporter and may thus be associated with Parkinson disease (PD). We therefore conducted a large case-control study investigating the potential relationship between MDR1 variants and PD. We determined the frequency of three MDR1 variants in 599 European PD patients and controls and further stratified the population by ethnicity, age at onset, and exposure to pesticides. We detected no relevant association in either the entire sample, or when separately investigating by ethnic origin or age at onset. However, the distribution of c.3435C/T differed significantly between PD patients exposed to pesticides compared to those non-exposed (odds ratio=4.74; confidence interval=[1.009; 22.306]); p=0.047), suggesting that common MDR1 variants might influence the risk to develop PD in conjunction with exposure to pesticides.

To further evaluate (1) transcranial sonography (TCS) for (pre)clinical diagnosis of Parkinson's disease (PD) and (2) to examine asymptomatic carriers of Parkin mutations we investigated substantia nigra (SN) hyperechogenicity in PD patients and unaffected subjects with and without Parkin mutations. The area (aSN) of the hyperechogenic SN were calculated bilaterally and study subjects were assigned to high versus low value groups. Eleven of the (affected and unaffected) mutation carriers had previously undergone 18-fluoro-dopa-(FDOPA)-PET scans. Fifty-eight individuals were investigated, including 24 with clinically definite and 34 without symptoms or signs of PD. Of the patients, three had one mutated and six had two mutated Parkin alleles. Of the unaffected subjects, 13 carried a single Parkin mutated allele. After dichotomization, 21 subjects had high and 37 subjects low values of mean aSN. Regarding the clinical status, 13 (62%) of the individuals with a high mean aSN had PD,while 26 (70%) of the study subjects with low values did not show signs of PD (p = 0.0393). Similarly, probands with high mean aSN values more frequently carried Parkin mutations (58%) than probands with low values (27%, p = 0.0234). A negative correlation between FDOPA uptake in the posterior putamen and maximum aSN was found in the group of mutation carriers (r = -0.809, p = 0.0234). In conclusion, hyperechogenicity of the SN is found in both idiopathic and Parkin-associated PD. Further strengthening the notion of a potential relationship between SN hyperechogenicity and Parkin mutational status, a larger aSN was associated with an increasing number of mutated alleles in our study.

Study of the nongenetic causes of Parkinson's disease (PD) was encouraged by discovery of a cluster of parkinsonism produced by neurotoxic pyridine 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) in the 1980s. Since that time, epidemiologic investigations have suggested risk factors, though their results do not establish causality. Pesticide exposure has been associated with increased risk in many studies. Other proposed risks include rural residence and certain occupations. Cigarette smoking, use of coffee/caffeine, and non-steroidal antiinflammatory drugs (NSAIDs) all appear to lower risk of PD, while dietary lipid and milk consumption, high caloric intake, and head trauma may increase risk. The cause of PD is likely multifactorial. Underlying genetic susceptibility and combinations of risk and protective factors likely all contribute. The combined research effort by epidemiologists, geneticists, and basic scientists will be needed to clarify the cause(s) of PD.