Case–control study of risk of Parkinson's disease in relation to hypertension, hypercholesterolemia, and diabetes in Japan

Serum cholesterol and nigrostriatal R2* values in Parkinson's disease

BACKGROUND

The occurrence of Parkinson's disease (PD) is known to be associated both with increased nigrostriatal iron content and with low serum cholesterol and PD, but there has been no study to determine a potential relationship between these two factors.

METHODS

High-resolution MRI (T1-, T2, and multiple echo T2*-weighted imaging) and fasting lipid levels were obtained from 40 patients with PD and 29 healthy controls. Iron content was estimated from mean R2* values (R2* = 1/T2*) calculated for each nigrostriatal structure including substantia nigra, caudate, putamen, and globus pallidus. This was correlated with serum cholesterol levels after controlling for age, gender, and statin use.

RESULTS

In patients with PD, higher serum cholesterol levels were associated with lower iron content in the substantia nigra (R = -0.43, p = 0.011 for total-cholesterol, R = -0.31, p = 0.080 for low-density lipoprotein) and globus pallidus (R = -0.38, p = 0.028 for total-cholesterol, R = -0.27, p = 0.127 for low-density lipoprotein), but only a trend toward significant association of higher total-cholesterol with lower iron content in the striatum (R = -0.34, p = 0.052 for caudate; R = -0.32, p = 0.061 for putamen). After adjusting for clinical measures, the cholesterol-iron relationships held or became even stronger in the substantia nigra and globus pallidus, but weaker in the caudate and putamen. There was no significant association between serum cholesterol levels and nigrostriatal iron content for controls.

CONCLUSIONS

The data show that higher serum total-cholesterol concentration is associated with lower iron content in substantia nigra and globus pallidus in Parkinson's disease patients. Further studies should investigate whether this is mechanistic or epiphenomenological relationship.

Diabetes and risk of Parkinson's disease: a systematic review and meta-analysis

OBJECTIVE

Diabetes has been associated with chronic neurodegeneration. We performed a systematic review and meta-analysis to assess the relationship between pre-existing diabetes and Parkinson's disease (PD).

RESEARCH DESIGN AND METHODS

Original articles in English published up to 10 May 2011 were searched for in electronic databases (PubMed, Embase, and Scopus) and by reviewing references of eligible articles. Prospective cohort and case-control studies providing risk and precision estimates relating to pre-existing diabetes and PD were considered eligible.

RESULTS

Nine studies/1,947 citations (cohort, N = 4; case-control, N = 5) fulfilled inclusion criteria for meta-analysis. In prospective studies, the onset of diabetes before onset of PD was found to be a risk factor for future PD (relative risk [RR] = 1.37 [95%CI 1.21-1.55]; P < 0.0001). This association was confirmed by secondary analyses based on estimates derived after the exclusion of participants who had vascular disease at baseline and/or who developed vascular disease during follow-up (RR = 1.34 [1.14-1.58]; P < 0.001) and by sensitivity analyses addressing the association with diabetes at baseline or during follow-up. However, the association found for case-control studies was not significant (odds ratio [OR] 0.75 [95%CI 0.50-1.11]; P = 0.835). Sensitivity analysis based on estimates adjusted for BMI confirmed the lack of a relationship between PD and diabetes (OR 0.56 [0.28-1.15]; P = 0.089).

CONCLUSIONS

Although data from cohort studies suggest that diabetes is a risk factor for PD, there is no conclusive evidence on this association. Further prospective studies focused on putative pathogenic pathways and taking a broad range of confounders into account is required to clarify this relationship.

Serum cholesterol and the progression of Parkinson's disease: results from DATATOP

BACKGROUND

Recent studies have suggested that higher serum cholesterol may be associated with lower occurrence of Parkinson's disease (PD). This study is to test the hypothesis that higher serum cholesterol correlates with slower PD progression.

METHODS

Baseline non-fasting serum total cholesterol was measured in 774 of the 800 subjects with early PD enrolled between 1987 and 1988 in the Deprenyl and Tocopherol Antioxidative Therapy of Parkinsonism (DATATOP) trial. Participants were followed for up to two years, with clinical disability requiring levodopa therapy as the primary endpoint. Hazard ratios (HRs) and 95% confidence intervals (CI) were determined for increasing serum cholesterol concentration (in quintiles) for clinical disability requiring levodopa therapy, after adjusting for confounders. At baseline, only nine subjects reported use of cholesterol-lowering agents (two with statins).

RESULTS

The overall mean cholesterol level was 216 mg/dL (range 100-355). The HR of progressing to the primary endpoint decreased with increasing serum cholesterol concentrations. Compared to the lowest quintile, the HRs (95%CI), for each higher quintile (in ascending order) are 0.83 (0.59-1.16); 0.86 (0.61-1.20); 0.84 (0.60-1.18); and 0.75 (0.52-1.09). The HR for one standard deviation (SD) increase = 0.90 [(0.80-1.01), p for trend = 0.09]. This trend was found in males (HR per SD = 0.88 [(0.77-1.00), p for trend = 0.05], but not in females [HR = 1.03 (0.81-1.32)].

CONCLUSIONS

This secondary analysis of the DATATOP trial provides preliminary evidence that higher total serum cholesterol concentrations may be associated with a modest slower clinical progression of PD, and this preliminary finding needs confirmation from larger prospective studies.

The risk of Parkinson disease associated with urate in a community-based cohort of older adults

BACKGROUND/AIMS

Studies suggest an inverse association between urate concentration and the risk of Parkinson disease (PD). We investigated this in the Cardiovascular Health Study in an elderly community-based cohort of adults.

METHODS

The association of baseline urate (µmol/l) and incident PD over 14 years was assessed with locally weighted scatterplot smoothing (LOESS) regression from which categories of low (<300 µmol/l), middle (300-500 µmol/l), and high (>500 µmol/l) urate ranges were derived. Multivariate logistic regression models assessed the risk of PD for each urate range. Linear and quadratic terms were tested when modeling the association between urate and the risk of PD.

RESULTS

Women had significantly lower urate concentrations than did men [316.8 µmol/l (SD 88.0) vs. 367.4 µmol/l (SD 87.7), p < 0.0001] and in women no associations between urate and PD risk were observed. In men, LOESS curves suggested a U-shaped or threshold effect between urate and PD risk. With the middle range as reference, the risk of developing PD was significantly increased for urate <300 µmol/l (OR 1.69, 95% CI 1.03-2.78) but not for urate >500 µmol/l (OR 1.55, 95% CI 0.72-3.32) in men. A negative linear term was significant for urate <500 µmol/l, and across the entire range a convex quadratic term was significant.

CONCLUSIONS

Results suggest a more complex relationship than previously reported between urate levels and the risk of PD in men. Low urate concentrations were associated with a higher PD risk and high urate concentrations were not associated with a further decrease in PD risk.

Association of Blood Pressure and Hypertension With the Risk of Parkinson Disease

Cardiovascular risk factors, such as diabetes mellitus and central obesity, have been associated with Parkinson disease (PD), but data on blood pressure and PD are lacking. We sought to examine the association of blood pressure and hypertension with the risk of PD among men and women. This study consisted of 7 surveys (1972–2002) on representative samples of the general population in Finland (National FINRISK Study). A total number of 59 540 participants (age 25 to 74 years; 51.8% women) who were free of PD and stroke at baseline were prospectively followed until December 31, 2006, to identify incident PD cases using the National Social Insurance Register database. Cox proportional hazards models were constructed to estimate the hazard ratio of PD associated with blood pressure. During a mean follow-up period of 18.8 years (SD: 10.2 years), 423 men and 371 women were ascertained to have developed PD. In women, compared with normotensive subjects (<130/80 mm Hg), the multivariable-adjusted hazard ratios of PD associated with high-normal blood pressure (130 to 139/80 to 89 mm Hg) and hypertension (≥140/90 mm Hg or use of antihypertensive agents) were 1.63 (95% CI: 1.07 to 2.47) and 1.62 (95% CI: 1.09 to 2.42). There was no significant association between blood pressure and PD risk in men. The multivariable-adjusted hazard ratios of PD associated with use of antihypertensive agents were 1.08 (95% CI: 0.79 to 1.48) in men and 1.03 (95% CI: 0.76 to 1.38) in women. This study suggests that, in women, above-optimal blood pressure, including high-normal blood pressure and hypertension, is associated with an increased risk of PD. Optimal control of blood pressure in women may reduce the incidence of PD.

Diabetes and the risk of developing Parkinson's disease in Denmark

OBJECTIVE

Insulin contributes to normal brain function. Previous studies have suggested associations between midlife diabetes and neurodegenerative diseases, including Parkinson's disease. Using Danish population registers, we investigated whether a history of diabetes or the use of antidiabetes drugs was associated with Parkinson's disease.

RESEARCH DESIGN AND METHODS

From the nationwide Danish Hospital Register hospital records, we identified 1,931 patients with a first-time diagnosis of Parkinson's disease between 2001 and 2006. We randomly selected 9,651 population control subjects from the Central Population Registry and density matched them by birth year and sex. Pharmacy records comprising all antidiabetes and anti-Parkinson drug prescriptions in Denmark were available. Odds ratios (ORs) were estimated by logistic regression models.

RESULTS

Having diabetes, as defined by one or more hospitalizations and/or outpatient visits for the condition, was associated with a 36% increased risk of developing Parkinson's disease (OR 1.36 [95% CI 1.08-1.71]). Similarly, diabetes defined by the use of any antidiabetes medications was associated with a 35% increased Parkinson's disease risk (1.35 [1.10-1.65]). When diabetes was defined as the use of oral antidiabetes medications, effect estimates were stronger in women (2.92 [1.34-6.36]), whereas when diabetes was defined as any antidiabetes drug prescription, patients with early-onset Parkinson's disease were at highest risk (i.e., Parkinson's disease diagnosed before the age of 60 years; 3.07 [1.65-5.70]).

CONCLUSIONS

We found that a diagnosis of, or treatment received for, diabetes was significantly associated with an increased risk of developing Parkinson's disease, especially younger-onset Parkinson's disease. Our results suggest a common pathophysiologic pathway between the two diseases. Future studies should take age at Parkinson's disease onset into account.

Diabetes and risk of Parkinson's disease

OBJECTIVE

To investigate the relationship between diabetes and future risk of Parkinson's disease (PD) among older U.S. adults.

RESEARCH DESIGN AND METHODS

A prospective study of self-reported diabetes in 1995 and 1996 in relation to PD diagnosed after 1995 among 288,662 participants of the National Institutes of Health-AARP Diet and Health Study. Multivariate odds ratio (OR) and 95% CI were derived from logistic regression models.

RESULTS

A total of 1,565 participants with PD diagnosed after 1995 were included in the analysis. After adjustment for potential confounders, PD risk was ∼40% higher (OR = 1.41 [95% CI 1.20-1.66]) among diabetic patients than among participants without diabetes. Further analysis showed that the risk elevation was largely limited to individuals who had diabetes for more than 10 years at the time of baseline survey (1.75 [1.36-2.25]). The association with diabetes was seen for both participants with PD diagnosed between 1995 and 1999 and participants with PD diagnosed after 2000. In addition, similar results were obtained after excluding participants with stroke, heart disease, cancers, or poor or fair health status and in subgroup analyses by age, sex, smoking status, and coffee consumption.

CONCLUSIONS

This large study showed that diabetes was associated with a higher future risk of PD and the nature of this association warrants further investigation.

Alcohol drinking and risk of Parkinson's disease: a case-control study in Japan

Background

Although some epidemiologic studies found inverse associations between alcohol drinking and Parkinson's disease (PD), the majority of studies found no such significant associations. Additionally, there is only limited research into the possible interactions of alcohol intake with aldehyde dehydrogenase (ALDH) 2 activity with respect to PD risk. We examined the relationship between alcohol intake and PD among Japanese subjects using data from a case-control study.

Methods

From 214 cases within 6 years of PD onset and 327 controls without neurodegenerative disease, we collected information on "peak", as opposed to average, alcohol drinking frequency and peak drinking amounts during a subject's lifetime. Alcohol flushing status was evaluated via questions, as a means of detecting inactive ALHD2. The multivariate model included adjustments for sex, age, region of residence, smoking, years of education, body mass index, alcohol flushing status, presence of selected medication histories, and several dietary factors.

Results

Alcohol intake during peak drinking periods, regardless of frequency or amount, was not associated with PD. However, when we assessed daily ethanol intake separately for each type of alcohol, only Japanese sake (rice wine) was significantly associated with PD (adjusted odds ratio of ≥66.0 g ethanol per day: 3.39, 95% confidence interval: 1.10-11.0, P for trend = 0.001). There was no significant interaction of alcohol intake with flushing status in relation to PD risk.

Conclusions

We did not find significant associations between alcohol intake and PD, except for the daily amount of Japanese sake. Effect modifications by alcohol flushing status were not observed.