Risk of dementia among antidepressant elderly users: A population-based cohort analysis in Spain

The use of antidepressants with anticholinergic effects has been associated with an increased risk of dementia. However, the results published are contradictory. The aim of the study is to compare the risk of developing dementia in elderly who were prescribed tricyclic antidepressants (TCA) versus those who were prescribed selective serotonin reuptake inhibitors (SSRIs) and other antidepressants (OA). A prospective population-based cohort study was performed using the Spanish Database for Pharmacoepidemiological Research in Primary Care (BIFAP) data (from 2005 to 2018). The cohort study included 62,928 patients age ≥ 60 without dementia and with antidepressant long-term monotherapy. Patients were divided into exposure antidepressant groups based on ATC system [TCA, SSRIs users and OAs users]. The risk of dementia was calculated by Cox regression models, providing hazard ratios (HR) and 95 % confidence intervals. The Kaplan-Meier model was used for survival analysis. Chi2 test was used as association test. The results showed SSRI users had higher dementia risk than TCA users (HR = 1.864; 95%CI = 1.624-2.140). Moreover, OA users had also significant risk of dementia (HR = 2.103; 95%CI = 1.818-2.431). Several limitations are the variation of the trend in the prescription of antidepressants, the small number of patients that use some antidepressants, the lack of information related to the dose, or socioeconomic characteristics, the use of antidepressant drugs for other indications, or the therapeutic compliance. Our findings showed that older users of SSRI and OA have more risk of developing dementia than TCA elderly users. However, additional studies would be needed.