Incident Parkinson's Disease Cases Research Articles

Use of Statins and the Risk of Parkinson???s Disease

Case reports have related the use of HMG-CoA reductase inhibitors ('statins') to Parkinson's disease (PD). Paradoxically, however, statins may have potentially beneficial effects on neurodegenerative diseases due to their anti-inflammatory properties. To explore the risk of the development of PD in association with untreated hyperlipidaemia and with hyperlipidaemia treated with lipid-lowering drugs in the UK primary care setting. We conducted a case-control analysis using the UK-based General Practice Research Database (GPRD). Cases were incident PD cases > or =40 years of age between 1994 and 2005. One control was matched to each PD case based on age, sex, general practice and index date. Lipid-lowering drug use was assessed by exposure timing (current vs past use) and by exposure duration (1-9, 10-29 or > or =30 prescriptions) prior to the index date for both cases and controls. Odds ratios (OR) were calculated using conditional logistic regression, adjusted for body mass index, smoking and various cardiovascular, metabolic and psychiatric co-morbidities. We identified 3637 cases with an incident idiopathic PD diagnosis, and the same number of controls. Compared with patients without hyperlipidaemia, those with untreated hyperlipidaemia did not have an altered relative PD risk (adjusted OR 0.98, 95% CI 0.74, 1.30). The adjusted ORs for current use of > or =30 prescriptions for statins or fibrates compared with non-use of statins or fibrates were 1.06 (95% CI 0.75, 1.51) and 1.25 (95% CI 0.51, 3.06), respectively. In this observational study, the long-term use of statins or fibrates was not associated with a substantially altered relative risk of developing PD.

Differential Effects of Black versus Green Tea on Risk of Parkinson's Disease in the Singapore Chinese Health Study

Data from Asian populations on dietary and lifestyle factors associated with Parkinson's disease are sparse. In 1993-2005, the authors examined these factors in relation to Parkinson's disease in the Singapore Chinese Health Study, a prospective cohort of 63,257 Chinese men and women. Baseline data were collected through in-person interviews using structured questionnaires. All 157 incident Parkinson's disease cases were identified either through follow-up interviews or via linkage with hospital discharge databases and Parkinson's disease outpatient registries and were confirmed by review of medical records. Current versus never smokers exhibited a reduced risk of Parkinson's disease (relative risk = 0.29, 95% confidence interval: 0.16, 0.52). Total caffeine intake was inversely related to Parkinson's disease risk (p for trend = 0.002); the relative risk for the highest versus lowest quartile was 0.55 (95% confidence interval: 0.35, 0.88). Black tea, a caffeine-containing beverage, showed an inverse association with Parkinson's disease risk that was not confounded by total caffeine intake or tobacco smoking (p for trend = 0.0006; adjusted relative risk for the highest vs. lowest tertile of intake = 0.29, 95% confidence interval: 0.13, 0.67). Green tea drinking was unrelated to Parkinson's disease risk. Diet had no strong influence on risk. Ingredients of black tea other than caffeine appear to be responsible for the beverage's inverse association with Parkinson's disease.

Nonsteroidal anti-inflammatory drugs may protect against Parkinson disease

Markers of neuroinflammation, including activated microglia and increased levels of circulating proinflammatory cytokines, have been observed in the brains and CSF of patients with Parkinson disease (PD). Yet the link between anti-inflammatory agents and PD in humans remains uncertain, despite indications that neuroinflammation may contribute to cell death in the PD brain and experimental evidence of anti-inflammatory agents such as nonsteroidal anti-inflammatory drugs (NSAIDs) exerting neuroprotective effects in animal models. Using a population-based approach, we studied NSAID use among 293 incident idiopathic PD cases and 286 age-, race-, and gender-matched controls from three rural California counties. Our data suggested a decreased risk of PD among regular (>or=2 pills/week for at least 1 month) aspirin NSAID users (OR, 0.80; 95% CI, 0.56 to 1.15). A stronger protective effect was observed for regular nonaspirin NSAID users (OR, 0.52; 95% CI, 0.35 to 0.79), particularly those who reported 2 or more years of use (OR, 0.44; 95% CI, 0.26 to 0.74). The aspirin effect estimates differed by gender, showing a protective effect only in women, especially among long term (>or=24 months) regular users (OR, 0.51; 95% CI, 0.26 to 1.02). Our study contributes to the growing body of literature suggesting a protective role for nonsteroidal anti-inflammatory drugs (NSAIDs) in Parkinson disease (PD). Given our results and the biologic plausibility of a neuroprotective function for NSAIDs there is a pressing need for further studies elucidating the protective role such drugs may play in PD.

Inflammatory Cytokine Gene Polymorphisms and Increased Risk of Parkinson Disease

The proinflammatory cytokines tumor necrosis factor alpha (TNF-alpha) and IL-1beta (interleukin 1beta) have a role in neuroinflammation, and functional polymorphisms in the TNF-alpha and IL-1beta genes may affect susceptibility to Parkinson disease (PD). To investigate whether functional DNA polymorphisms of the TNF-alpha and IL-1beta genes affect the risk of PD. Population-based case-control study. Three rural California counties (Fresno, Tulare, and Kern). Two hundred eighty-nine incident idiopathic PD cases and 269 population control subjects, marginally matched by age, sex, and race/ethnicity. Genotypes of IL-1beta-511 and TNF-alpha-308. We observed a greater than 2-fold increased risk of PD among carriers of the homozygous variant genotype of IL-1beta-511 (odds ratio [OR], 2.26; 95% confidence interval [CI], 1.27-4.02) and the homozygous variant genotype of TNF-alpha-308 (OR, 2.49; 95% CI, 0.90-6.85) and an almost 3-fold increased risk among carriers of the homozygous variant genotype for either or both polymorphisms (OR, 2.92; 95% CI, 1.66-5.16). A smaller magnitude of PD risk increase among carriers of the heterozygous genotype for either or both polymorphisms suggests a gene-dosing effect (OR, 1.45; 95% CI, 0.97-2.16; P<.001 for trend). Results were not sensitive to exclusion of all nonwhite subjects or to adjustment for nonsteroidal anti-inflammatory drug use or smoking.

Identifying incident cases of parkinsonism among veterans using a tertiary medical center

To better understand the impact of incident Parkinson's disease (PD) on the Veteran's Health Administration (VHA) and to develop methods applicable to future epidemiological research, we performed a medical record review study at a tertiary referral VHA medical center. Searching the local data base, we identified 782 veterans with diagnostic codes for PD or secondary parkinsonism (SP) between 1998 and 2000. Based on structured medical record review, a movement disorders specialist confirmed diagnoses for incident parkinsonism cases. Among the 782, 191 incident parkinsonism cases were identified (100 PD, 75 SP, and 16 Parkinson's Plus). Incident PD cases were older at diagnosis (74.5 vs. 70.4 yr; P < 0.05) and more likely to be white (81% vs. 62; P < 0.07) than incident SP cases. Diagnostic codes were insufficient to distinguish between incident PD and SP (positive predictive value, 57% and 39%, respectively), and VHA sources failed to identify 21% of confirmed deaths among the incident PD cohort by November 2004. Although the large number of incident cases identified suggests PD is an important cause of disability among elderly VHA users, observed limitations of VHA sources for identifying incident PD cases and determining their vital status should be considered when designing future studies.

Glutathione S-transferase mu, omega, pi, and theta class variants and smoking in Parkinson's disease

GSTs are a family of inducible phase II enzymes that may play a neuroprotective role in Parkinson's disease (PD). GSTs may also modify PD risk by metabolizing compounds in cigarettes, as cigarette smoking is generally found to be associated with a decrease in PD risk. Using a population-based case–control study design, we examined polymorphisms of the mu, omega, pi, and theta classes of GST to elucidate the main effects and smoking–GST interactions on PD risk. From three rural California counties, we recruited 289 incident idiopathic PD cases, clinically confirmed by our study neurologist, and 270 population controls, marginally matched by age, gender, and race. We assessed main gene polymorphism associations and evaluated interactions between smoking and GST polymorphisms as departures from a multiplicative scale adjusting for age, gender, and race. We also restricted analyses to Caucasian subjects to address the potential for population stratification ( n = 235 cases, 220 controls). Among Caucasians, we observed a risk reduction in subjects carrying at least one variant allele for GSTO1 (OR = 0.68, 95% CI: 0.47–0.98) and also GSTO2 (OR = 0.64, 95% CI: 0.44–0.93); both genes were in strong linkage disequilibrium. No main gene effects were observed for the remaining polymorphisms. We noted a multiplicative interaction between ever having smoked regularly and GSTO1 (OR interaction = 0.55, 95% CI: 0.33–0.92) and GSTO2 (OR interaction = 0.54, 95% CI: 0.32–0.90). Results were similar when combining all races. These findings and the paucity of similar studies suggest a need for further inquiry into the association between GSTs, smoking, and PD risk.

Incidence of Parkinson's disease in Singapore

To investigate the incidence of Parkinson's disease (PD) in Singapore, a parkinsonism-free cohort of 14,835 participants was followed-up and incident cases of PD identified through phone interviews, medical record reviews and a hospital's database. A movement disorders specialist subsequently verified the diagnosis through a medical records review. The age and sex-adjusted (US 1990 population) incidence rate was 32 per 100,000 person years for individuals aged 50 years and above. The rates differed between Chinese, Malays and Indians ( p=0.03). The difference in inter-racial rates needs to be interpreted with caution in view of the small numbers. The incidence of PD in Singapore is comparable with that in Western countries.

A Prospective Study of Night Shift Work, Sleep Duration, and Risk of Parkinson's Disease

The authors prospectively investigated whether working rotating night shifts was associated with the risk of Parkinson's disease among 84,794 female nurses who reported years of night shift work in 1988 (the US Nurses' Health Study). After 975,912 person-years of follow-up (1988-2000), 181 incident Parkinson's disease cases were documented. Compared with nurses who never worked rotating night shifts, those with 15 years or more of night shift work had a 50% lower risk of Parkinson's disease after adjustment for age and smoking (95% confidence interval: 0.26, 0.97; p(trend) = 0.01). Sleep duration was positively associated with Parkinson's disease risk: The relative risk was 1.84 (95% confidence interval: 0.99, 3.42) when comparing nurses who reported 9 or more hours of sleep per day with those who slept 6 hours or less (p(trend) = 0.005). These data suggest that working night shifts may be protective against Parkinson's disease or that low tolerance for night shift work is an early marker of Parkinson's disease. Conversely, habitual longer sleep duration may be an earlier marker of Parkinson's disease. Because of the novelty and the exploratory nature of these findings, confirmation is needed.

Burden of disease related to Parkinson's disease in Spain in the year 2000

We measured the burden caused by Parkinson's disease (PD) in Spain during the year 2000 and compared it against PD burden worldwide and in the European A subregion. Burden of disease (BoD) is an important factor in health policy. Disability-adjusted life years (DALY) as a measure of BoD is the result of adding years of life lost (YLL) and years lived with disability (YLD). The burden of PD (BPD) has not been studied in Spain. YLL were obtained from the Spanish death certificates and YLD from the estimated number of incident PD cases and the average PD duration. PD disability was calculated, using the Disability Weights for Diseases in the Netherlands. Prior PD DALY data for Europe and the world were obtained from the 2001 World Health Organization World Health Report. A discount rate of 3% and age-weighting modulation factor with K = 1 were used. In Spain, PD generated 67,582 DALY, comprising 6,351 (9.4%) YLL and 61,231 (90.6%) YLD. Most PD DALY (57.5%) occurred in the population 60 to 74 years of age. When PD DALY estimates were adjusted using the world population in 2000, Spain registered a PD DALY rate of 84 per 100,000 population, higher than both the world and European A subregion rates (24 and 35 per 100,000 population, respectively). PD burden in Spain in 2000 was high, with disability being the major contributing factor. Although BPD in Spain was greater than both world and European A subregion BPD, these differences should nevertheless be interpreted with caution.

Physical activity and the risk of Parkinson disease

To investigate whether greater physical activity is associated with a lower risk of Parkinson disease (PD). The authors prospectively followed 48,574 men and 77,254 women who provided information on physical activity in 1986 or in early adulthood. During the follow-up, a total of 252 (male) and 135 (female) incident PD cases were identified. In men, greater baseline physical activity was associated with a lower PD risk; compared with the lowest quintile, the multivariate relative risk (RR) of PD for the highest quintile was 0.7 (95% CI 0.5 to 1.1; p value, test for trend = 0.007), and the inverse association was still present after excluding the first 10 years of follow-up (RR = 0.5; p value, test for trend = 0.02). Further, strenuous exercise in early adult life was also inversely related to PD risk in men: compared with men who regularly exercised < or =2 months/year, those with > or =10 months of strenuous exercise had a 60% lower PD risk (RR = 0.4; p value, test for trend = 0.005). In women, physical activity assessed at baseline was not related to PD risk, whereas strenuous exercise in early adulthood tended to be inversely related to PD risk later in life (highest vs lowest categories, RR = 0.5, 95% CI 0.2 to 1.4; p value, test for trend = 0.06). This study suggests either that higher levels of physical activity may lower the risk of Parkinson disease (PD) in men or that men predisposed to PD tend to avoid strenuous physical activity in their early adult years.

Survival study of Parkinson disease in Olmsted County, Minnesota.

To compare survival in incident cases of Parkinson disease (PD) with survival in subjects free of PD from the general population. We used the medical records linkage system of the Rochester Epidemiology Project to identify incident cases of PD in Olmsted County, Minnesota, for the period 1976-1995. Cases were matched by age and sex to referent subjects from the same population. For 196 cases and 185 referent subjects, we studied survival between the date of diagnosis of PD (or index date) and death, loss to follow-up, or end of the study (May 1, 2000). The median length of follow-up was 7.2 years for cases and 8.0 years for referent subjects; 110 patients with PD and 79 referent subjects died during follow-up. The median survival was 10.3 years in cases and 13.4 years in referent subjects. The relative risk (RR) of death was 1.60 (95% confidence interval [CI], 1.20-2.14; P =.002) overall, 1.81 (95% CI, 1.15-2.84; P =.01) in women, and 1.49 (95% CI, 1.01-2.20; P =.04) in men. There was a decreasing trend in the RR of death according to age at onset of PD (in tertiles): younger than 67 years, RR, 2.04 (95% CI, 0.99-4.19; P =.05); 67 to 76 years, RR, 1.76 (95% CI, 1.08-2.86; P =.02); and older than 76 years, RR, 1.48 (95% CI, 0.95-2.29; P =.08). Patients with PD who had both rest tremor and pronounced asymmetry had a better prognosis than patients with neither clinical characteristic. Patients with PD who smoked survived better than expected. Patients with PD face a higher risk of death compared with subjects free of PD from the general population. Certain clinical characteristics and smoking modify survival.

Diet and Parkinson's disease: a potential role of dairy products in men.

Diet may play a causative role in Parkinson's disease (PD), but potential associations between diet and PD risk rarely have been assessed in prospective studies. We investigated associations between food intakes and PD risk in two large prospective cohorts in which 210 incident PD cases in men and 184 in women were documented. A positive association was found between dairy intake and PD risk in men (relative risk [RR] comparing extreme categories, 1.8; p trend = 0.004), but not in women (RR, 1.1; p trend = 0.9). No other food groups were associated with PD risk in either men or women. Further analyses among men showed significant positive associations with PD risk for intakes of several dairy foods as well as dairy calcium (RR, 1.5; p trend = 0.02), dairy vitamin D (RR, 1.6; p trend = 0.004), dairy protein (RR, 1.6; p trend = 0.01), and lactose (RR, 1.8; p trend = 0.002), but not dairy fat (RR, 1.1; p trend = 0.4). Intakes of calcium, vitamin D, and protein from other dietary or supplemental sources were not related to PD risk in men. Our results suggest that higher intake of dairy products may increase the risk of PD in men; however, this finding needs further evaluation, and the underlying active components need to be identified.

Parkinson's disease risks associated with cigarette smoking, alcohol consumption, and caffeine intake.

A reduced risk for Parkinson's disease (PD) among cigarette smokers has been observed consistently during the past 30 years. Recent evidence suggests that caffeine may also be protective. Findings are presented regarding associations of PD with smoking, caffeine intake, and alcohol consumption from a case-control study conducted in western Washington State in 1992-2000. Incident PD cases (n = 210) and controls (n = 347), frequency matched on gender and age were identified from enrollees of the Group Health Cooperative health maintenance organization. Exposure data were obtained by in-person questionnaires. Ever having smoked cigarettes was associated with a reduced risk of PD (odds ratio (OR) = 0.5, 95% confidence interval (CI): 0.4, 0.8). A stronger relation was found among current smokers (OR = 0.3, 95% CI: 0.1, 0.7) than among ex-smokers (OR = 0.6, 95% CI: 0.4, 0.9), and there was an inverse gradient with pack-years smoked (trend p < 0.001). No associations were detected for coffee consumption or total caffeine intake or for alcohol consumption. However, reduced risks were observed for consumption of 2 cups/day or more of tea (OR = 0.4, 95% CI: 0.2, 0.9) and two or more cola drinks/day (OR = 0.6, 95% CI: 0.3, 1.4). The associations for tea and cola drinks were not confounded by smoking or coffee consumption.