Chronic Pain Increases the Risk of Dementia: A Nationwide Population-Based Cohort Study

Background: Chronic pain (CP) may increase the risk of cognitive impairment; however, the association between CP and dementia is still unclear. Objectives: Therefore, we conducted this study to clarify the association between CP and dementia. Study Design: Retrospective cohort study. Settings: Nationwide population based. Methods: This study recruited 27,792 patients (>= 50 years) with CP from the Taiwan National Health Insurance Research Database between January 1, 2000, and December 31, 2015, as the study cohort. The comparison cohort consists of patients without CP who were matched 1:1 for age, gender, and index date with the study cohort. A comparison of the risk of dementia between the two cohorts was performed by following up until 2015. Results: The prevalence of CP was 13.4% in the population aged >= 50 years. Patients with CP had a higher risk of dementia than those without CP (adjusted hazard ratio [AHR]: 1.21; 95% confidence interval [CI]: 1.15-1.26). Compared with the other age subgroups, the 50-64 years age group with CP had the highest risk of dementia (AHR: 1.28; 95% CI: 1.14-1.43). The impact of CP on the increased risk of dementia was more prominent in the younger age subgroup and decreased with aging. The increased risk of dementia in patients with CP was persistent, even following up for more than 5 years (AHR: 1.19; 95% CI: 1.12-1.26). Limitations: Using "analgesics use at least 3 months" as the surrogate criteria of CP may underestimate the diagnosis of CP. Conclusions: CP was associated with a higher risk of dementia, especially in the 5064 years age group. Early treatment of CP for the prevention of dementia is suggested.