Rheumatic and Musculoskeletal Diseases and Risk of Dementia: A Nested Case‐Control Study

Abstract

Objective To investigate the associations between rheumatic and musculoskeletal diseases (RMDs) and incident dementia using population register‐based data. Methods This nested case‐control study was conducted based on a cohort of residents in the Skåne region, Sweden, aged 50 years and older in 2009 without doctor‐diagnosed dementia during 1998 to 2009 (n = 402,825). Individuals with a new main diagnosis of dementia during 2010 to 2019 were identified as incident patients with dementia (n = 22,131). Controls without diagnosed dementia were randomly matched 1:1 by sex, age, and Elixhauser comorbidity index using incidence density sampling. Separate conditional logistic regression analyses adjusted for confounders were fitted for the following RMDs, diagnosed at least 2 years before dementia diagnosis as exposure: gout, osteoarthritis, rheumatoid arthritis, spondyloarthropathies (SpA), and systemic connective tissue disorders. Subgroup analyses by dementia subtype, sex, age, comorbidity, and RMDs/dementia identification were conducted. Results Although gout (adjusted rate ratio 0.88; 95% confidence interval 0.79–0.97), osteoarthritis (0.92; 0.88–0.96), and systemic connective tissue disorders (0.91; 0.83–0.99) were associated with decreased risk of dementia, the associations for rheumatoid arthritis (1.05; 0.92–1.19) and SpA (1.17; 0.94–1.45) were inconclusive. The associations between RMDs and incident dementia were similar across sex, age, and comorbidity subgroups with a few exceptions (eg, an adjusted rate ratio of 0.99 [95% confidence interval 0.71–1.39] in males vs 1.31 [0.99–1.74] in female patients for SpA). Conclusion Persons with diagnosed RMDs seem to have comparable or slightly lower risks of developing dementia compared with those without known RMD.