Prevalence and risk factors of cognitive impairment in Parkinson disease: a population-based case-control study in Taiwan

Age-Stratified Risk of Dementia in Parkinson's Disease: A Nationwide, Population-Based, Retrospective Cohort Study in Taiwan

Introduction: Parkinson's disease (PD) manifests with dominant motor symptoms and a wide range of non-motor symptoms (NMS). Dementia is one of the most disabling and exhausting NMS throughout the clinical course. We conducted a population-based, age-stratified, retrospective cohort study to investigate the incidence rate and risk of dementia of patients with newly diagnosed PD, and linked to the clinicopathological PD subtypes.

Methods: Patients with newly diagnosed PD (PD group, n = 760) and control subjects (non-PD group, n = 3,034) were selected from the Taiwan's National Health Insurance Research Database from January 2001 to December 2005. The dementia incidence rate and dementia-free survival rate were calculated.

Results: The overall dementia incidence rate was 17.5 and 5.7 per 1,000 person-years in PD and non-PD groups, respectively. The PD group had a significantly higher overall risk of dementia than controls (p < 0.001). The younger PD patients had a lower dementia incidence rate than the older PD patients, but a higher dementia risk compared to the same age of controls (<60 years, adjusted HR 6.55, 95% CI 1.56–27.48, p = 0.010). The dementia-free survival rate was significantly lower in the PD group compared to the non-PD group during follow-up (p < 0.001).

Conclusion: In our study, the older age of onset in PD patients resulted in a higher incidence rate of dementia. In the young age of PD patients, the incidence rate of dementia was lower than the older PD patients, but the dementia risk was higher than controls of the same age. These findings possibly implied that there were different pathogenesis and pathologies causing dementia in younger and older PD patients.

Risk of dementia after Parkinson's disease in Taiwan: a population-based retrospective cohort study using National Health Insurance claims

OBJECTIVES

A nationwide cohort study on the risk of dementia onset after first diagnosis of Parkinson's disease (PD) is lacking. This study aims to assess 11 years of incidence and the HRs for developing dementia in patients with PD compared with matched controls.

DESIGN

A population-based cohort study.

SETTING

National Health Insurance database in Taiwan.

PARTICIPANTS

A total of 5932 patients with PD were identified, and 29 645 age-matched, sex-matched and index year-matched PD-free individuals were randomly selected.

OUTCOME MEASURES

All subjects were linked to the claim data to identify the first diagnosis of dementia. The Poisson assumption was used to estimate the incidence rate. Cause-specific hazards models with a partitioning of time at 1 year to account for proportionality were used to estimate the risk of dementia onset.

RESULTS

The median duration from the first diagnosis of PD to the development of dementia was 9.02 years. In the first partition (≦ 1 year), the incidence of dementia in the PD and control groups was 114.49 and 9.76 per 1000 person-years, respectively, with an adjusted HR of 6.43 (95% CI 5.46 to 7.57). In the second partition (>1 year), the incidence of dementia in the PD and control groups was 30.99 and 10.83 per 1000 person-years, with an adjusted HR of 2.42 (95% CI 2.23 to 2.61). Notably, in the second partition, both men and women aged <70 years had the highest HR (3.82, 95% CI 2.79 to 5.22 and 4.27, 95% CI 3.25 to 5.63, respectively).

CONCLUSIONS

This study noted an increased risk of dementia after a diagnosis of PD. The magnitude of effect estimation was higher in men in the first partition but was similar in both genders in the second partition. PD patients aged <70 years have the highest risk of dementia in any given partition time.