Adult Asthma Increases Dementia Risk- A Nationwide Population-Based Cohort Study

Background/objective: Studies on the association between asthma and dementia are few. We investigated the risk of dementia in patients diagnosed with asthma compared with that of people without asthma who were age- and sex- matched to the study patients. Methods: We used data from the National Health Insurance Research Database. A total of 12 771 patients aged over 20 years and newly diagnosed with asthma between 2001 and 2003 were evaluated, and 51 084 people without asthma were used as a comparison cohort. A Chi-square test and t test was used to determine the difference in categorical and continuous variables between the 2 cohorts, and incidence (per 1000 person-y) of dementia was calculated for both cohorts. Cox proportional hazard regression analysis was used to measure the hazard ratio (HR) of dementia for the asthmatic cohort, compared with that of the nonasthmatic cohort. Results: The HR of dementia was 1.16 (95% confident interval [CI]=1.05-1.28) for the asthmatic cohort, compared with the nonasthmatic cohort, after adjusting for age, sex, and comorbidities. Compared with the comparison cohort, the dementia risk increased as the number of ER visits, admissions, or combined ER visits and admissions for asthma increased, from 1.13 (95% CI=1.03-1.25) to 19.8 (95% CI=9.36-41.7), 1.12 (95% CI=1.02-1.24) to 6.86 (95% CI=3.65-12.9), and 1.11 (95% CI=1.01-1.22) to 6.42 (95% CI=3.90-10.6), respectively. Conclusions: This nationwide cohort study suggests that the risk of dementia development is significantly increased in patients with asthma compared with that of the general population. In addition, dementia risk increases substantially as asthma exacerbation and hospitalization frequency increases.