Environmental exposure to pesticides and the risk of Parkinson's disease in the Netherlands.

BACKGROUND: Exposure to pesticides has been linked to Parkinson's disease (PD), although associations between specific pesticides and PD have not been well studied. Residents of rural areas can be exposed through environmental drift and volatilization of agricultural pesticides. OBJECTIVES: Our aim was to investigate the association between lifetime environmental exposure to individual pesticides and the risk of PD, in a national case-control study. METHODS: Environmental exposure to pesticides was estimated using a spatio-temporal model, based on agricultural crops around the residential address. Distance up to 100m from the residence was considered most relevant, considering pesticide drift potential of application methods used in the Netherlands. Exposure estimates were generated for 157 pesticides, used during the study period, of which four (i.e. paraquat, maneb, lindane, benomyl) were considered a priori relevant for PD. RESULTS: A total of 352 PD cases and 607 hospital-based controls were included. No significant associations with PD were found for the a priori pesticides. In a hypothesis generating analysis, including 153 pesticides, increased risk of PD was found for 21 pesticides, mainly used on cereals and potatoes. Results were suggestive for an association between bulb cultivation and PD. CONCLUSIONS: For paraquat, risk estimates for the highest cumulative exposure tertile were in line with previously reported elevated risks. Increased risk of PD was observed for exposure to (a cluster of) pesticides used on rotating crops. High correlations limited our ability to identify individual pesticides responsible for this association. This study provides some evidence for an association between environmental exposure to specific pesticides and the risk of PD, and generates new leads for further epidemiological and mechanistic research.

In vitro neurotoxic hazard characterisation of dinitrophenolic herbicides.

Dinitrophenolic compounds are powerful toxicants with a long history of use in agriculture and industry. While (high) human exposure levels are not uncommon, in particular for agricultural workers during the spraying season, the neurotoxic mechanism(s) that underlie the human health effects are largely unknown. We therefore investigated the in vitro effects of two dinitrophenolic herbicides (DNOC and dinoseb) on a battery of neurotoxicity endpoints in (dopaminergic) rat PC12 cells. Cell viability, mitochondrial activity, oxidative stress and caspase activation were assessed using fluorescence-based bioassays (CFDA, alamar Blue, H2DCFDA and Ac-DEVD-AMC, respectively), whereas changes in intracellular [Ca(2+)]i were assessed using single-cell fluorescence microscopy with Fura-2AM. The combined results demonstrate that exposure to both DNOC and dinoseb is linked to calcium release from the endoplasmic reticulum and activation of caspase-mediated apoptotic pathways. In subsequent experiments, immunofluorescent labelling with specific antibodies was used to determine changes in intracellular α-synuclein levels, demonstrating that both DNOC and dinoseb increase levels of intracellular α-synuclein. The combined results indicate that in vitro exposure to DNOC and dinoseb activates pathways that are not only involved in acute neurotoxicity but also in long-term effects as seen in neurodegeneration.

Neuronal ceroid lipofuscinosis with DNAJC5/CSPα mutation has PPT1 pathology and exhibit aberrant protein palmitoylation.

Neuronal ceroid lipofuscinoses (NCL) are a group of inherited neurodegenerative disorders with lysosomal pathology (CLN1-14). Recently, mutations in the DNAJC5/CLN4 gene, which encodes the presynaptic co-chaperone CSPα were shown to cause autosomal-dominant NCL. Although 14 NCL genes have been identified, it is unknown if they act in common disease pathways. Here we show that two disease-associated proteins, CSPα and the depalmitoylating enzyme palmitoyl-protein thioesterase 1 (PPT1/CLN1) are biochemically linked. We find that in DNAJC5/CLN4 patient brains, PPT1 is massively increased and mis-localized. Surprisingly, the specific enzymatic activity of PPT1 is dramatically reduced. Notably, we demonstrate that CSPα is depalmitoylated by PPT1 and hence its substrate. To determine the consequences of PPT1 accumulation, we compared the palmitomes from control and DNAJC5/CLN4 patient brains by quantitative proteomics. We discovered global changes in protein palmitoylation, mainly involving lysosomal and synaptic proteins. Our findings establish a functional link between two forms of NCL and serve as a springboard for investigations of NCL disease pathways.

Occupational exposure to solvents, metals and welding fumes and risk of Parkinson's disease.

OBJECTIVES: The aim of this study was to investigate the potential association between occupational exposure to solvents, metals and/or welding fumes and risk of developing Parkinson's disease (PD). METHODS: Data of a hospital based case-control study including 444 PD patients and 876 age and sex matched controls was used. Occupational histories and lifestyle information of cases and controls were collected in a structured telephone interview. Exposures to aromatic solvents, chlorinated solvents and metals were estimated by linking the ALOHA+ job-exposure matrix to the occupational histories. Exposure to welding fumes was estimated using self-reported information on welding activities. RESULTS: No statistically significant associations with any of the studied metal and solvent exposures were found. However, for self-reported welding activities we observed non-statistically significant reduced risk estimates (third tertile cumulative exposure: OR = 0.51 (95% CI: 0.21-1.24)). CONCLUSIONS: The results of our study did not provide support for an increased chance on developing PD after occupational exposure to aromatic solvents, chlorinated solvents or exposure to metals. The results showed reduced risk estimates for welding, which is in line with previous research, but no clear explanation for these findings is available.

Extremely low-frequency magnetic field exposure, electrical shocks and risk of Parkinson's disease.

PURPOSE: Previous studies did not provide strong evidence for an increased Parkinson's disease (PD) risk after exposure to extremely low-frequency magnetic fields (ELF-MF), but were limited in their scope to address other exposures related to the use of electricity such as electrical shocks. We evaluated the associations of PD with exposure to ELF-MF, electrical shocks and having worked in "electrical occupations." METHODS: We conducted a hospital-based case-control study, including 444 PD patients and 876 age- and sex-matched controls. Occupational histories were collected in telephone interviews and were linked to job-exposure matrices on ELF-MF exposure and on electrical shocks. In addition, questions on use of household appliances involving ELF-MF exposure, experienced electrical shocks and potential confounders were asked. RESULTS: No association of PD risk with any of the evaluated exposures related to electricity was observed. We did, however, observe quite consistently reduced risk estimates across the majority of the exposure categories explored. Given the results of the previous studies and the absence of any postulated mechanism, this is unlikely to represent a true protective effect of ELF-MF or electrical shocks on the occurrence of PD. CONCLUSIONS: The results of this study suggest that no association exists between PD and exposure to ELF-MF, electrical shocks or having worked in "electrical occupations."

Occupational exposure to pesticides and endotoxin and Parkinson disease in the Netherlands.

OBJECTIVES: Previous research has indicated that occupational exposure to pesticides and possibly airborne endotoxin may increase the risk of developing Parkinson disease (PD). We studied the associations of PD with occupational exposure to pesticides, specifically to the functional subclasses insecticides, herbicides and fungicides, and to airborne endotoxin. In addition we evaluated specific pesticides (active ingredients) previously associated with PD. METHODS: We used data from a hospital-based case-control study, including 444 patients with PD and 876 age and sex matched controls. Exposures to pesticides from application and re-entry work were estimated with the ALOHA+job-exposure matrix and with an exposure algorithm based on self-reported information on pesticide use. To assess exposure to specific active ingredients a crop-exposure matrix was developed. Endotoxin exposure was estimated with the DOM job-exposure matrix. RESULTS: The results showed almost no significant associations. However, ORs were elevated in the higher exposure categories for pesticides in general, insecticides, herbicides and fungicides, and below unity for endotoxin exposure. The analyses on specific active ingredients showed a significant association of PD risk with the fungicide benomyl. CONCLUSIONS: This study did not provide evidence for a relation between pesticide exposure and PD. However, the consistently elevated ORs in the higher exposure categories suggest that a positive association may exist. The possible association with the active ingredient benomyl requires follow-up in other studies. This study did not provide support for a possible association between endotoxin exposure and PD.

A case-control study of the protective effect of alcohol, coffee, and cigarette consumption on Parkinson disease risk: time-since-cessation modifies the effect of tobacco smoking.

The aim of this study was to investigate the possible reduced risk of Parkinson Disease (PD) due to coffee, alcohol, and/or cigarette consumption. In addition, we explored the potential effect modification by intensity, duration and time-since-cessation of smoking on the association between cumulative pack-years of cigarette smoking (total smoking) and PD risk. Data of a hospital based case-control study was used including 444 PD patients, diagnosed between 2006 and 2011, and 876 matched controls from 5 hospitals in the Netherlands. A novel modeling method was applied to derive unbiased estimates of the potential modifying effects of smoking intensity, duration, and time-since-cessation by conditioning on total exposure. We observed no reduced risk of PD by alcohol consumption and only a weak inverse association between coffee consumption and PD risk. However, a strong inverse association of total smoking with PD risk was observed (OR=0.27 (95%CI: 0.18-0.42) for never smokers versus highest quartile of tobacco use). The observed protective effect of total smoking was significantly modified by time-since-cessation with a diminishing protective effect after cessation of smoking. No effect modification by intensity or duration of smoking was observed indicating that both intensity and duration have an equal contribution to the reduced PD risk. Understanding the dynamics of the protective effect of smoking on PD risk aids in understanding PD etiology and may contribute to strategies for prevention and treatment.

Subthalamic nucleus versus globus pallidus bilateral deep brain stimulation for advanced Parkinson's disease (NSTAPS study): a randomised controlled trial.

BACKGROUND: Patients with advanced Parkinson's disease often have rapid swings between mobility and immobility, and many respond unsatisfactorily to adjustments in pharmacological treatment. We assessed whether globus pallidus pars interna (GPi) deep brain stimulation (DBS) gives greater functional improvement than does subthalamic nucleus (STN) DBS. METHODS: We recruited patients from five centres in the Netherlands who were aged 18 years or older, had idiopathic Parkinson's disease, and had, despite optimum pharmacological treatment, at least one of the following symptoms: severe response fluctuations, dyskinesias, painful dystonias, or bradykinesia. By use of a computer-generated randomisation sequence, we randomly assigned patients to receive either GPi DBS or STN DBS (1:1), applying a minimisation procedure according to drug use (levodopa equivalent dose <1000 mg vs ≥1000 mg) and treatment centre. Patients and study assessors (but not those who assessed adverse events) were masked to treatment allocation. We had two primary outcomes: functional health as measured by the weighted Academic Medical Center Linear Disability Scale (ALDS; weighted by time spent in the off phase and on phase) and a composite score for cognitive, mood, and behavioural effects up to 1 year after surgery. Secondary outcomes were symptom scales, activities of daily living scales, a quality-of-life questionnaire, the occurrence of adverse events, and drug use. We used the intention-to-treat principle for all analyses. This trial is registered with www.controlled-trials.com, number ISRCTN85542074. FINDINGS: Between Feb 1, 2007, and March 29, 2011, we enrolled 128 patients, assigning 65 to GPi DBS and 63 to STN DBS. We found no statistically significant difference in either of our primary outcomes: mean change in weighted ALDS (3·0 [SD 14·5] in the GPi group vs 7·7 [23·2] in the STN group; p=0·28) and the number of patients with cognitive, mood, and behavioural side-effects (36 [58%] of 62 patients in the GPi group vs 35 [56%] of 63 patients in the STN group; p=0·94). Secondary outcomes showed larger improvements in off-drug phase in the STN group compared with the GPi group in the mean change in unified Parkinson's disease rating scale motor examination scores (20·3 [16·3] vs 11·4 [16·1]; p=0·03), the mean change in ALDS scores (20·3 [27·1] vs 11·8 [18·9]; p=0·04), and medication (mean levodopa equivalent drug reduction: 546 [SD 561] vs 208 [521]; p=0·01). We recorded no difference in the occurrence of adverse events between the two groups. Other secondary endpoints showed no difference between the groups. INTERPRETATION: Although there was no difference in our primary outcomes, our findings suggest that STN could be the preferred target for DBS in patients with advanced Parkinson's disease. FUNDING: Stichting Internationaal Parkinson Fonds, Prinses Beatrix Fonds, and Parkinson Vereniging.

Mutations in DNAJC5, encoding cysteine-string protein alpha, cause autosomal-dominant adult-onset neuronal ceroid lipofuscinosis.

Autosomal-dominant adult-onset neuronal ceroid lipofuscinosis (ANCL) is characterized by accumulation of autofluorescent storage material in neural tissues and neurodegeneration and has an age of onset in the third decade of life or later. The genetic and molecular basis of the disease has remained unknown for many years. We carried out linkage mapping, gene-expression analysis, exome sequencing, and candidate-gene sequencing in affected individuals from 20 families and/or individuals with simplex cases; we identified in five individuals one of two disease-causing mutations, c.346_348delCTC and c.344T>G, in DNAJC5 encoding cysteine-string protein alpha (CSPα). These mutations-causing a deletion, p.Leu116del, and an amino acid exchange, p.Leu115Arg, respectively-are located within the cysteine-string domain of the protein and affect both palmitoylation-dependent sorting and the amount of CSPα in neuronal cells. The resulting depletion of functional CSPα might cause in parallel the presynaptic dysfunction and the progressive neurodegeneration observed in affected individuals and lysosomal accumulation of misfolded and proteolysis-resistant proteins in the form of characteristic ceroid deposits in neurons. Our work represents an important step in the genetic dissection of a genetically heterogeneous group of ANCLs. It also confirms a neuroprotective role for CSPα in humans and demonstrates the need for detailed investigation of CSPα in the neuronal ceroid lipofuscinoses and other neurodegenerative diseases presenting with neuronal protein aggregation.

Autosomal dominant adult neuronal ceroid lipofuscinosis: a novel form of NCL with granular osmiophilic deposits without palmitoyl protein thioesterase 1 deficiency.

We describe the neuropathological and biochemical autopsy findings in 3 patients with autosomal dominant adult neuronal ceroid lipofuscinosis (ANCL, Parry type; MIM 162350), from a family with 6 affected individuals in 3 generations. Throughout the brain of these patients, there was abundant intraneuronal lysosomal storage of autofluorescent lipopigment granules. Striking loss of neurons in the substantia nigra was found. In contrast, little neuronal cell loss occurred in other cerebral areas, despite massive neuronal inclusions. Visceral storage was present in gut, liver, cardiomyocytes, skeletal muscle, and in the skin eccrine glands. The storage material showed highly variable immunoreactivity with antiserum against subunit c of mitochondrial ATP synthase, but uniform strong immunoreactivity for saposin D (sphingolipid activating protein D). Protein electrophoresis of isolated storage material revealed a major protein band of about 14 kDa, recognized in Western blotting by saposin D antiserum (but not subunit c of mitochondrial ATPase (SCMAS) antiserum). Electron microscopy showed ample intraneuronal granular osmiophilic deposits (GRODs), as occurs in CLN1 and congenital ovine NCL. These forms of NCL are caused by the deficiencies of palmitoyl protein thioesterase 1 and cathepsin D, respectively. However, activities of these enzymes were within normal range in our patients. Thus we propose that a gene distinct from the cathepsin D and CLN1-CLN8 genes is responsible for this autosomal dominant form of ANCL.

Autosomal dominant adult neuronal ceroid lipofuscinosis: parkinsonism due to both striatal and nigral dysfunction.

We describe a family with adult neuronal ceroid lipofuscinosis, with apparent autosomal dominant inheritance, observed in six affected individuals in three generations. Disease onset was usually in the fifth decade, but was earlier in the youngest generation. Early symptoms consisted of myoclonus in face and arms, epilepsy, auditory symptoms, cognitive decline, or depression. Parkinsonism occurred a few years after disease onset, with stooped posture, shuffling gait, bradykinesia, and mask face. Four subjects deteriorated to a state of severe handicap, with severe dementia, contractures, dysphagia, and dysarthria. Leg weakness evolved to flaccid paraparesis in two patients. Diagnosis was confirmed by brain biopsy in one patient and full autopsy in two patients. Abundant intraneuronal storage of autofluorescent material was found throughout the brain. Electron microscopy showed granular osmiophilic deposits and scarce fingerprint profiles. Striking loss of neurons in the substantia nigra pars compacta and reticulata was found. (123)I-IBZM Single photon emission computed tomography in two patients showed loss of postsynaptic D2 receptor binding in the striatum. We conclude that parkinsonism in ANCL is likely to be caused by both presynaptic nigral cell loss and postsynaptic striatal degeneration.