Association between dementia risk and ulcerative colitis, with and without colectomy: a Swedish population-based register study

OBJECTIVE: This study aims to investigate the association of ulcerative colitis (UC) with all-cause dementia and assess differences in those with and without a total colectomy. DESIGN, SETTING AND PARTICIPANTS: This Swedish prospective register-based study comprised 4.8 million individuals aged at least 59 years between 1964 and 2018 with the linkage of several Swedish national registers. PRIMARY AND SECONDARY OUTCOME MEASURES: Individuals with dementia were defined according to International Classification of Diseases diagnostic codes and Anatomical Therapeutic Classification codes for medication prescriptions. Fitting Cox hazards models, the risk of developing all-cause dementia in individuals with and without UC was estimated. Further, we compared the risk of all-cause dementia among those with and without a colectomy. RESULTS: Among 4 821 488 individuals (52.6% females) followed for 84.1 million person-years between 1964 and 2018, the incidence rate of all-cause dementia was 63.90 (63.73-64.07) events per 10 000 person-years in individuals without UC, 94.80 (92.04-97.64) among those with UC, 95.01 (92.25-97.86) in those with UC but without colectomy and 63.42 (40.92-98.31) in those with UC and a colectomy. Adjusted Cox models showed an increased all-cause dementia risk in individuals with UC (HR 1.07, 95% CI 1.04 to 1.10). We found no differences between unexposed individuals and those with UC and a colectomy (HR 0.89, 95% CI 0.57 to 1.38). CONCLUSION: The findings are consistent with previous evidence suggesting a slightly increased dementia risk among individuals with UC. This study provided no evidence of further risk increase of dementia among those who had a colectomy.