To investigate the relationship between intracranial pressure (ICP), anterior pituitary hormones, and structural brain changes in women with idiopathic intracranial hypertension (IIH). Eighteen women with therapy-refractory IIH underwent lumbar puncture, endocrine assessment, and high-resolution brain MRI. Serum levels of pituitary hormones were correlated with ICP and radiological parameters including pituitary volume, flattening, and optic nerve (ON) and optic nerve sheath (ONS) volume. Group comparisons and partial correlations were used to evaluate associations. ICP showed a significant positive association with thyroid-stimulating hormone (TSH) levels (r = 0.628, p = 0.016), and a significant negative association with growth hormone (GH) (r = −0.602, p = 0.023). Regarding structural parameters, only the volume of the right ON showed a strong positive association within the subgroup with elevated ICP (r = 0.90, p = 0.005). Correlations between ONS volumes and ICP in the normal pressure subgroup narrowly missed statistical significance. TSH was the only hormone showing a significant association, with higher TSH levels relating to larger pituitary volume in the normal ICP subgroup (r = 0.88, p = 0.020), but not in the elevated ICP subgroup. Our exploratory findings suggest potential interactions between ICP, endocrine markers, and structural MRI measures. However, due to the limited sample size and variability in endocrine parameters, the results should be interpreted cautiously and considered hypothesis generating rather than clinically directive. Larger studies are needed to determine whether endocrine MRI associations hold true and whether they have diagnostic or clinical relevance.

Magnetic resonance-guided focused ultrasound (MRgFUS) is a promising, noninvasive therapeutic approach for essential tremor (ET), yet the effects of the respective lesions on functional brain network organization remain poorly understood. Here, we performed graph theory analysis to investigate changes in small-world properties and modular architecture in ET patients six months after unilateral MRgFUS of the thalamic ventral intermediate (VIM) nucleus. Small-worldness and normalized clustering coefficient increased significantly after MRgFUS, while clustering coefficient, characteristic path length, normalized characteristic path length, global efficiency, and local efficiency remained unchanged. Modular organization was largely preserved, but trend-level enhancements in inter-modular connectivity were observed between frontoparietal and subcortical modules, as well as between frontoparietal and frontotemporal-parietal modules. Within these modules, betweenness centrality increased significantly in specific cortical hubs, including the left superior frontal gyrus, right superior parietal lobule, and left postcentral gyrus. These findings indicate that unilateral VIM-MRgFUS induces selective functional network reorganization, particularly affecting relative clustering and nodal centrality patterns.

Magnetic resonance-guided focused ultrasound (MRgFUS) thalamotomy in essential tremor (ET) targets ventral intermediate nucleus hub region within cerebello-thalamo-cortical tract (CTCT). Understanding the microstructural changes in CTCT over time and their link to tremor improvement is crucial from a tremor-network perspective. We retrospectively analyzed tremor scores, lesion characteristics, and diffusion MRI-derived CTCT microstructural measures in 27 ET patient's pre-treatment (T0), at 1 month (T2), and 6 months (T3) post-MRgFUS. Using probabilistic tractography, we created an average CTCT mask at T0 for assessing fractional anisotropy (FA), axial (AD), mean (MD), and radial diffusivity (RD) measures across time points. Significant tremor reduction was observed at T2 and T3. The Linear mixed effect analyses showed significant time effects for FA, MD, and AD. Relative to baseline, post-hoc comparisons showed a significant decrease of FA and AD at lesion site only for T2. Instead, there was a significant increase in AD and MD at T3 compared to T2 at lesion site, and remotely near the motor cortex. Lesion size and FA changes in the CTCT at T2 showed only trend-level correlations with tremor outcome. Stronger associations were observed for the thalamic lesion-tract overlap at T2, which were even more robust at T3. Dynamic microstructural changes suggest early axonal disruption at the lesion site and subsequent reorganization, with remote CTCT changes potentially indicating chronic degeneration. Meanwhile, microstructural measures show limited predictive value for tremor outcome at 6 months compared with macroanatomical lesion-CTCT overlap. Yet, advanced diffusion imaging protocol could increase the sensitivity to predict MRgFUS clinical outcome.

Parkinson's disease (PD) is marked by motor symptoms and often accompanied by mild cognitive impairment (PD-MCI), affecting up to 50% of patients and preceding PD dementia (PDD). Genetic factors may influence this progression, yet the underlying mechanisms remain unclear. This study investigated genetic factors influencing the progression from PD-MCI to PDD using polygenic risk scores (PRS). A genome-wide association study (GWAS) was conducted using data from the LANDSCAPE study. Multivariable Cox regression, Kaplan-Meier survival analysis, and concordance statistics assessed the relationship between PRS and PDD progression. No significant association was found between PD PRS and the risk of developing PDD.

Precise targeting in magnetic resonance-guided focused ultrasound (MRgFUS) is critical for effective tremor control in essential tremor and tremor-dominant Parkinson's disease, as small deviations can reduce efficacy or cause side effects. In our cohort, sweetspots were identified at Montreal Neurological Institute (MNI) coordinates x = -12.4, y = -17.5, z = -1.7 (ET) and x = -13.4, y = -19.8, z = -3.0 (TDPD).

Current treatment of Parkinson’s Disease (PD) remains symptomatic, and disease-modifying approaches are urgently required. A promising approach is to modify intestinal microbiota and key metabolites of bacterial fermentation: short-chain fatty acids (SCFA), which are decreased in PD. A prospective, controlled pilot study (DRKS00034528) was conducted on 11 couples (PD patient plus healthy spouse as control (CO)). Participants followed a 4-week diet rich in dietary fibre, including intake of the prebiotic Lactulose. Gut metagenomes, faecal and urinary metabolites, and clinical characteristics were assessed. The dietary intervention significantly augmented faecal SCFA and increased Bifidobacteria spp., reducing PD-related gastrointestinal symptoms. The pre-existing bacterial dysbiosis in PD (depletion of Blautia, Dorea, Erysipelatoclostridium) persisted. Bacterial metabolite composition in faeces and urine positively changed with the intervention: Brain-relevant gut metabolic functions involved in neuroprotective and antioxidant pathways, including S-adenosyl methionine, glutathione, and inositol, improved in PD. These promising results warrant further investigation in larger cohorts.

The challenge of early detection and stratification in Parkinson's disease (PD) is urgent due to the current emergence of mechanism-based disease-modifying treatments. In here, metabolomic and lipidomic parameters obtained by a standardized and targeted in vitro diagnostic research (IVDr) platform have a significant potential to address therapy-related questions and generate improved biomarker panels. Our study aimed to use IVDr nuclear magnetic resonance (NMR) spectroscopy to quantify metabolites and lipoproteins in PD blood serum from different cohorts to stratify metabolically driven subtypes of idiopathic and genetic PD. Serum aliquots from three neurodegeneration biobank cohorts (287 samples in total, including 62 PD patient samples with GBA mutation, 98/43 PD patient samples of early/late stages of disease duration, 20 PD samples from patients with mutations in recessive PD genes and some smaller subgroups of mitochondrial and double mutation cases) were prepared and analyzed with IVDr NMR spectroscopy, covering 39 blood serum metabolites and 112 lipoprotein parameters. Uni- and multivariate statistics were used to identify metabolism-driven changes under consideration of typical confounders such as age, sex and disease duration and set into context with clinical biomarkers such as CSF concentrations of alpha-synuclein, neurofilament light chain, and tau protein. Based on the different PD subgroups we performed a total of eight different comparisons. Highlights from these comparisons include increased citrate and dimethylglycine with a decrease of creatinine and methionine in healthy controls and early PD group compared to GBA, PD late and recessive PD. We furthermore identified decreased HDL-3 free cholesterol in genetic PD cases compared to sporadic subject samples (sum of the PD early and PD late groups). Considering medication, we found that the levodopa equivalent daily dose (LEDD) is mostly positively correlated with tyrosine and citrate in sporadic PD compared to pyruvate and phenylalanine in genetic PD. Cerebrospinal fluid levels of alpha-synuclein were negatively correlated with alanine. Further metabolites and lipoproteins with discriminatory power for double mutation PD cases involved ornithine, 2-aminobutyrate and 2-hydroxybutyrate as well as for mitochondrial phenotypes via LDL phospholipid, apolipoprotein and cholesterol subfractions. Quantitative IVDr NMR serum spectroscopy is able to stratify PD patient samples of different etiology and can contribute to a wider understanding of the underlying metabolism-driven alterations e.g. in energy, amino acid, and lipoprotein metabolism. Though our overall cohort was large, major confounders such as age, sex and medication have a strong impact. That is why absolute quantification and detailed patient knowledge about metabolic confounders, is a premise for future translation of NMR serum spectroscopy to routine PD diagnostics.

ABSTRACT Despite extensive research, current treatment of Parkinson's Disease (PD) remains symptomatic and disease modifying approaches are urgently required. A promising approach is to target the gut-brain-axis by modifying the intestinal microbiota and the herein produced metabolites. We decided to test this approach by modifying key metabolites of bacterial intestinal fermentation: short chain fatty acids (SCFA), known to be decreased in PD patients. A prospective, controlled pilot study was conducted in 11 couples, with one PD patient and healthy spouse as control (CO) each. Participants followed a 4-week diet rich in dietary fibre in addition to the intake of a prebiotic sirup (Lactulose). Metagenomes and metabolites of the gut microbiota, urinary metabolites and clinical characteristics were assessed. The short-term dietary intervention significantly augmented gastrointestinal SCFA production, likely associated with increased Bifidobacteria spp. PD associated gastrointestinal symptoms improved with increasing SCFA levels. The pre-existing bacterial dysbiosis associated with PD, such as depletion of genera Blautia, Dorea, and Erysipelatoclostridium in PD, persisted within the study period. Some pathobionts, i.e. Klebsiella, were reduced after the intervention. Bacterial metabolite composition (both faecal and urine metabolomes) shifted towards the composition of the healthy control in PD after the intervention. Among these brain-relevant gut metabolic functions improved in PD patients, such as S-Adenosyl methionine (SAM), 3,4-Dihydroxyphenylacetic acid (DOPAC), Glutathione (GSH), Tryptophan and inositol related changes, involved in neuroprotective and antioxidant pathways. Despite the small cohort size and short-term study period a minor dietary intervention was sufficient to improve gastrointestinal symptoms in PD and altered metabolic parameters in a presumed neuroprotective manner, warranting further investigation in larger cohorts. ### Competing Interest Statement The authors have declared no competing interest. ### Clinical Trial DRKS00034528 ### Funding Statement This study was funded by the Hilde-Ulrichs-Foundation for Parkinson's research. This research was also supported by the BBSRC Institute Strategic Programme (ISP) Food Microbiome and Health BB/X011054/1 and its constituent project BBS/E/F/000PR13631, the BBSRC Core Capability Grant BB/CCG2260/1 and its constituent project BBS/E/QU/23NB0006, the ISP Decoding Biodiversity BBX011089/1, projects BBS/E/ER/230002A and BBS/E/ER/230002B, and Cellular Genomics Cellular Genomics BBX011070/1, project BBS/E/ER/230001A. The funders played no role in study design, data collection, analysis and interpretation of data, or the writing of this manuscript. JRB was supported by a local grant (FEMHabil) at the medical faculty of the University Hospital Bonn. FH was supported by European Research Council H2020 StG (erc-stg-948219, EPYC). We thank Lia Mareen Taube for her support during the study performance. ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: The ethics committee of the University of Bonn, Germany, gave ethical approval for this work (internal ethics vote 145/17). I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes The metagenomic sequencing data generated and/ analysed during the current study is available in the European Nucleotide Archive, ENA repository, PRJEB57228. Further data types are available upon request from the corresponding authors.

Mounting evidence suggests a prominent role for alpha-synuclein (a-syn) in neuronal cell function. Alterations in the levels of cellular a-syn have been hypothesized to play a critical role in the development of Parkinson's disease (PD); however, mechanisms that control expression of the gene for a-syn (SNCA) in cis and trans as well as turnover of a-syn are not well understood. We analyzed whether methyl-CpG binding protein 2 (MeCP2), a protein that specifically binds methylated DNA, thus regulating transcription, binds at predicted binding sites in intron 1 of the SNCA gene and regulates a-syn protein expression. Chromatin immunoprecipitation (ChIP) and electrophoretic mobility-shift assays (EMSA) were used to confirm binding of MeCP2 to regulatory regions of SNCA. Site-specific methylation and introduction of localized mutations by CRISPR/Cas9 were used to investigate the binding properties of MeCP2 in human SK-N-SH neuroblastoma cells. The significance of MeCP2 for SNCA regulation was further investigated by overexpressing MeCP2 and mutated variants of MeCP2 in MeCP2 knockout cells. We found that methylation-dependent binding of MeCP2 at a restricted region of intron 1 of SNCA had a significant impact on the production of a-syn. A single nucleotide substitution near to CpG1 strongly increased the binding of MeCP2 to intron 1 of SNCA and decreased a-syn protein expression by 60%. In contrast, deletion of a single nucleotide closed to CpG2 led to reduced binding of MeCP2 and significantly increased a-syn levels. In accordance, knockout of MeCP2 in SK-N-SH cells resulted in a significant increase in a-syn production, demonstrating that SNCA is a genomic target for MeCP2 regulation. In addition, the expression of two mutated MeCP2 variants found in Rett syndrome (RTT) showed a loss of their ability to reduce a-syn expression. This study demonstrates that methylation of CpGs and binding of MeCP2 to intron 1 of the SNCA gene plays an important role in the control of a-syn expression. In addition, the changes in SNCA regulation found by expression of MeCP2 variants carrying mutations found in RTT patients may be of importance for the elucidation of a new molecular pathway in RTT, a rare neurological disorder caused by mutations in MECP2.

To elucidate the molecular basis of multiple system atrophy (MSA), a neurodegenerative disease, we conducted a genome-wide association study (GWAS) in a Japanese MSA case/control series followed by replication studies in Japanese, Korean, Chinese, European and North American samples. In the GWAS stage rs2303744 on chromosome 19 showed a suggestive association ( P = 6.5 × 10 -7 ) that was replicated in additional Japanese samples ( P = 2.9 × 10 -6 . OR = 1.58; 95% confidence interval, 1.30 to 1.91), and then confirmed as highly significant in a meta-analysis of East Asian population data ( P = 5.0 × 10 -15 . Odds ratio= 1.49; 95% CI 1.35 to 1.72). The association of rs2303744 with MSA remained significant in combined European/North American samples ( P =0.023. Odds ratio=1.14; 95% CI 1.02 to 1.28) despite allele frequencies being quite different between these populations. rs2303744 leads to an amino acid substitution in PLA2G4C that encodes the cPLA2γ lysophospholipase/transacylase. The cPLA2γ-Ile143 isoform encoded by the MSA risk allele has significantly decreased transacylase activity compared with the alternate cPLA2γ-Val143 isoform that may perturb membrane phospholipids and α-synuclein biology.

Glioblastoma is the most common and aggressive primary tumor of the central nervous system with poor outcome. Current gold standard treatment is surgical resection followed by a combination of radio- and chemotherapy. Efficacy of temozolomide (TMZ), the primary chemotherapeutic agent, depends on the DNA methylation status of the O6-methylguanine DNA methyltransferase (MGMT), which has been identified as a prognostic biomarker in glioblastoma patients. Clinical studies revealed that glioblastoma patients with hypermethylated MGMT promoter have a better response to TMZ treatment and a significantly improved overall survival. In this study, we thus used the CRISPRoff genome editing tool to mediate targeted DNA methylation within the MGMT promoter region. The system carrying a CRISPR-deactivated Cas9 (dCas9) fused with a methyltransferase (Dnmt3A/3L) domain downregulated MGMT expression in TMZ-resistant human glioblastoma cell lines through targeted DNA methylation. The reduction of MGMT expression levels reversed TMZ resistance in TMZ-resistant glioblastoma cell lines resulting in TMZ induced dose-dependent cell death rates. In conclusion, we demonstrate targeted RNA-guided methylation of the MGMT promoter as a promising tool to overcome chemoresistance and improve the cytotoxic effect of TMZ in glioblastoma.

The Berlin questionnaire is commonly used to screen for obstructive sleep apnea (OSA), but has not yet been validated in patients with intracranial aneurysm. Evidence indicates OSA to be a modifiable risk factor for poor outcome from intracranial aneurysm (e.g., subarachnoid hemorrhage). In this study, we determine the sensitivity and specificity of the Berlin questionnaire to identify patients with OSA in this population. We analyzed data from 185 patients with intracranial aneurysm from two prospective studies who had completed the Berlin questionnaire and undergone respiratory polygraphy to diagnose OSA. We calculated the sensitivity, specificity, positive predictive value, and negative predictive value of the Berlin questionnaire for detecting patients with OSA (apnea–hypopnea index [AHI] ≥ 5/h) and moderate to severe OSA (AHI ≥ 15/h). The Berlin questionnaire indicated 50.8

The heterogeneity of Parkinson’s disease (PD), i.e. the various clinical phenotypes, pathological findings, genetic predispositions and probably also the various implicated pathophysiological pathways pose a major challenge for future research projects and therapeutic trail design. We outline several pathophysiological concepts, pathways and mechanisms, including the presumed roles of α-synuclein misfolding and aggregation, Lewy bodies, oxidative stress, iron and melanin, deficient autophagy processes, insulin and incretin signaling, T-cell autoimmunity, the gut–brain axis and the evidence that microbial (viral) agents may induce molecular hallmarks of neurodegeneration. The hypothesis is discussed, whether PD might indeed be triggered by exogenous (infectious) agents in susceptible individuals upon entry via the olfactory bulb (brain first) or the gut (body-first), which would support the idea that disease mechanisms may change over time. The unresolved heterogeneity of PD may have contributed to the failure of past clinical trials, which attempted to slow the course of PD. We thus conclude that PD patients need personalized therapeutic approaches tailored to specific phenomenological and etiologic subtypes of disease.

COPYRIGHT © 2023 Sharma, Wüllner, Schmidt-Wolf and Maciaczyk. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms. Marginalizing the genomic architecture to identify crosstalk across cancer and neurodegeneration

Background:Parkinson's disease (PD) is characterized by motor disorders and the composition of Lewy bodies (LBs) in the substantia nigra. Due to the lack of a definitive biomarker, the current treatments do not modify the progression of PD. Recently, researchers revealed lipid dysregulation and some potential volatile biomarkers of PD related to a unique odor from PD patients by metabolomics of sebum, which is supposed to cause a potential change for skin microflora. In this study, we identified the 4 Malassezia species in PD patients and compared them with healthy controls. Methods:We collected 95 sebum samples (47 PDs and 48 Controls) by cotton swabs and extracted the DNA. The identification of Malassezia species was performed by Nested PCR. Specific primers for each species were used to amplify corresponding yeasts in each sample. Results:M. restricta and M. globosa are the most common species for both groups. The prevalence of M. slooffiae and M. sympodialis were significantly higher in the PD group compared with controls (63.8% vs. 29.1 and 74.5% vs. 54.2% respectively), the binary logistic regression model further indicated that M. slooffiae (OR = 9.358, p < 0.001) was associated with PD. Moreover, the diversity of Malassezia species was significantly greater (3.5 vs. 2.9 species per individual, p = 0.002) in the PD group. Conclusion:Based on our results, we preliminarily observed a change in Malassezia species incidence and diversity on the skin of PD patients, which could be associated with lipid dysregulation; meanwhile, it might also be a noninvasive biomarker for PD.

Magnetic resonance-guided focused ultrasound (MRgFUS) lesioning of the ventralis intermedius nucleus (VIM) has shown promise in treating drug-refractory essential tremor (ET). It remains unknown whether focal VIM lesions by MRgFUS have broader restorative effects on information flow within the whole-brain network of ET patients. We applied an information-theoretical approach based on intrinsic ignition and the concept of transfer entropy (TE) to assess the spatiotemporal dynamics after VIM-MRgFUS. Eighteen ET patients (mean age 71.44 years) underwent repeated 3T resting-state functional magnetic resonance imaging combined with Clinical Rating Scale for Tremor (CRST) assessments one day before (T0) and one month (T1) and six months (T2) post-MRgFUS, respectively. We observed increased whole brain ignition-driven mean integration (IDMI) at T1 (p < 0.05), along with trend increases at T2. Further, constraining to motor network nodes, we identified significant increases in information-broadcasting (bilateral supplementary motor area (SMA) and left cerebellar lobule III) and information-receiving (right precentral gyrus) at T1. Remarkably, increased information-broadcasting in bilateral SMA was correlated with relative improvement of the CRST in the treated hand. In addition, causal TE-based effective connectivity (EC) at T1 showed an increase from right SMA to left cerebellar lobule crus II and from left cerebellar lobule III to right thalamus. In conclusion, results suggest a change in information transmission capacity in ET after MRgFUS and a shift towards a more integrated functional state with increased levels of global and directional information flow.

Spinocerebellar ataxia type 3 (SCA 3) is a rare devastating neurodegenerative disorder caused by the expansion of CAG repeats in exon 10 of the ataxin-3 (ATXN3) gene, resulting in the expression of polyglutamine (polyQ) expanded mutant protein (mATXN3) (reviewed in Paulson).1 PolyQ aggregation in general has been shown to follow seeded growth polymerization kinetics with either the size or the concentration of an aggregation intermediate being critical for the fibrillization process.2, 3 Therefore, it is reasonable to argue that strategies aiming at decreasing the amount of aggregation prone mATXN3 species, or ATXN3 in general, could provide direct therapeutic benefit. Using mouse and other model organisms, we and others have shown that decreased ATXN3 does not lead to apparent morphological abnormalities or premature death.4 Allele-specific exon skipping resulted in lower mATXN3 levels and aggregate load in a SCA3-YAC mouse model.5 Similar results have been observed with various micro RNA approaches, suggesting that strategies to decrease ATXN3 expression in human SCA3 patients would be safe and of direct therapeutic value.6-9 We developed a quantitative assay based on a fluorophore-labeled, highly specific antibody to ATXN3 and recombinant human ATXN3 purified to homogeneity, serving as standard to determine absolute amounts of ATXN3 and observed considerable variation of normal and mATXN3 in human peripheral blood mononuclear cells (PBMC). Between 0.5 and 3 nanograms ATXN3 were present per microgram protein (Supplementary Fig. 1). The well-known inverse correlation between CAG repeat length and age at onset was reflected in our cohort, suggesting that the cohort was representative despite the small number. No clear cut correlation with age, sex, or the severity of ataxia (scale for the assessment and rating of ataxia score) became apparent with absolute amounts of normal or mATXN3; similar to what has been observed recently (data not shown).10, 11 Independent of the absolute amount, however, the ratio of normal to mATXN3 correlated with the age at onset of motor symptoms (ie, the more mATXN3 relative to normal ATXN3 was present in PBMC, the earlier the age at onset (Fig. 1). This phenomenon points to the importance of the individual relative proportion of expanded, dysfunctional protein, and fits with the idea of a toxic gain of function of mATXN3. As we observed no clear cut correlation with age and little variation with repeated sampling, measurement of ATXN3 in PBMC appears as a feasible tool to determine the amount of both normal and mATXN3 in an individual over time and therefore, to evaluate the effect of compounds or molecular tools, which supposedly lower neuronal ATXN3 expression in a clinical trial. It will be interesting to evaluate a putative change of ATXN3 expression in PBMC after systemic (or intrathecal) application of a canonical drug or antisense-oligonucleotides, because we are concerned that the amount of ATXN3 in cerebrospinal fluid (CSF) might be to low to measure, even with a highly specific and sensitive assay. Whether the relative amounts of ATXN3 will develop into a useful biomarker for SCA3 (ie, whether this ratio has a prognostic value in individuals at risk before the onset of obvious motor signs) remains to be determined in larger longitudinal cohorts. Appendix S1. Supporting Information Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

Background: Epigenetic factors including DNA methylation contribute to specific patterns of gene expression. Gene–environment interactions can change the methylation status in the brain, and accumulation of these epigenetic changes over a lifespan may be co-responsible for a neurodegenerative disease like Parkinson’s disease, which that is characterised by a late onset in life. Aims: To determine epigenetic modifications in the brains of Parkinson’s disease patients. Patients and Methods: DNA methylation patterns were compared in the cortex tissue of 14 male PD patients and 10 male healthy individuals using the Illumina Methylation 450 K chip. Subsequently, DNA methylation of candidate genes was evaluated using bisulphite pyrosequencing, and DNA methylation of cytochrome P450 2E1 (CYP2E1) was characterized in DNA from blood mononuclear cells (259 PD patients and 182 healthy controls) and skin fibroblasts (10 PD patients and 5 healthy controls). Protein levels of CYP2E1 were analysed using Western blot in human cortex and knock-out mice brain samples. Results: We found 35 hypomethylated and 22 hypermethylated genes with a methylation M-value difference >0.5. Decreased methylation of cytochrome P450 2E1 (CYP2E1) was associated with increased protein levels in PD brains, but in peripheral tissues, i.e., in blood cells and skin fibroblasts, DNA methylation of CYP2E1 was unchanged. In CYP2E1 knock-out mice brain alpha-synuclein (SNCA) protein levels were down-regulated compared to wild-type mice, whereas treatment with trichloroethylene (TCE) up-regulated CYP2E1 protein in a dose-dependent manner in cultured cells. We further identified an interconnected group of genes associated with oxidative stress, such as Methionine sulfoxide reductase A (MSRA) and tumour protein 73 (TP73) in the brain, which again were not paralleled in other tissues and appeared to indicate brain-specific changes. Conclusions: Our study revealed surprisingly few dysmethylated genes in a brain region less affected in PD. We confirmed hypomethylation of CYP2E1.

The question whether life style may impair the advent or course of the disease in patients with Parkinsonism is of great importance for patients and physicians alike. We present here comprehensive information on the influence of the environment, diet (especially caffeine, nicotine, alcohol, chocolate and dairy products), physical activity and sleep on risk and course of Parkinson's disease.