Association Between Psoriasis and Dementia: A Retrospective Cohort Study

Background: To date, no large study has examined the relationship between psoriasis and dementia in Germany. Objective: The aim of this study was to assess the association between psoriasis and the risk of all-cause dementia in patients followed in general practices in Germany. Methods: This retrospective cohort study is based on longitudinal data from the IQVIA (TM) Disease Analyzer database and included patients with an initial diagnosis of psoriasis between January 1995 and December 2014 in 1,173 general practices in Germany. Patients without psoriasis were matched individually (1:1) to psoriasis patients using propensity scores. The main outcome of the study was the cumulative incidence of dementia diagnoses within up to 15 years of the index date. Univariate Cox proportional regression models were used to assess the relationship between psoriasis or psoriatic arthritis and dementia. Results: The present study included 10,583 patients with a diagnosis of psoriasis and 10,583 controls without psoriasis. After 15 years of follow-up, 22.0% of the psoriasis patients and 19.1% (p < 0.001) of the non-psoriasis patients developed dementia. The incidence rate of dementia in 1,000 person-years was 15.0 in psoriasis patients and 11.9 in the non-psoriasis cohort. Psoriasis was significantly associated with a dementia risk (HR: 1.24; 95% CI: (1.14-1.35); p < 0.001). The association was stronger in patients with PsA (HR: 1.35; 95% CI: (0.98-1.86)) but this was not significant (p = 0.070). Conclusion: The present study found a positive association between psoriasis and all-cause dementia in patients in general practices in Germany.