Myeloproliferative Neoplasms and Dementia Risk: A Population‐Based Cohort Study

ABSTRACT Objectives To estimate dementia risk for persons diagnosed with Philadelphia chromosome–negative myeloproliferative neoplasms (MPNs), which serve as a human chronic inflammation model. Methods We identified 9895 individuals in Denmark newly diagnosed with MPNs from 1995 to 2017; matched them 10:1 by age and sex with a general population cohort of 95 770 individuals; and followed them until dementia identification, death, emigration, or December 31, 2018. We applied a Cox proportional‐hazards regression model to estimate the cause‐specific hazard ratios (HRs) and 95% confidence intervals (CIs) for dementia. We included control diseases, like chronic lymphocytic leukemia (CLL), which is not characterized by chronic inflammation. Results Patients with MPNs showed a 1.15‐fold (95% CI: 1.04–1.27) increased incidence of dementia compared with members of the general population. Associations were stronger for men with MPNs (HR: 1.40, 95% CI: 1.19–1.63) than for women (HR: 1.02, 95% CI: 0.89–1.15). Patients with CLL showed a decreased dementia incidence (HR: 0.81, 95% CI: 0.72–0.90). The findings for CLL could be explained by depletion‐of‐susceptibles bias, suggesting that the findings for MPNs were underestimated by a similar bias. Conclusions The findings support MPNs as risk factors for dementia and the role of chronic inflammation in dementia development.