Understanding the Association Between Antidepressants and the Risk of Being Diagnosed with Dementia in Older People: A Self-Controlled Case Series Study

Article type: Research Article

Authors: Xu, Zhongzhi^{a; c} | Yang, Jiannan^a | Lau, Kui Kai^b | Yip, Paul S.F.^c | Wong, Ian C.K.^{d; e; *} | Zhang, Qingpeng^{a; *}

Affiliations: [a] School of Data Science, City University of Hong Kong, Kowloon, Hong Kong, China | [b] Department of Medicine, The University of Hong Kong, Hong Kong, China | [c] Hong Kong Jockey Club Centre for Suicide Research and Prevention, The University of Hong Kong, Hong Kong, China | [d] Centre for Safe Medication Practice and Research, Department of Pharmacology and Pharmacy, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China | [e] Centre for Medicines Optimisation Research and Education, Research Department of Policy and Practice, University College London School of Pharmacy, London, UK

Correspondence: [*] Correspondence to: Ian C.K. Wong, PhD, Head of Department, Lo Shiu Kwan Kan Po Ling Professorship in Pharmacy, The University of Hong Kong, Hong Kong S.A.R., China. E-mail: wongick@hku.hk.; Qingpeng Zhang, PhD, Associate Professor, School of Data Science, City University of Hong Kong, Hong Kong S.A.R., China. E-mail: qingpeng.zhang@cityu.edu.hk.

Abstract: Background:Given concerns about adverse outcomes for older people taking antidepressants in the literature, we investigated whether taking antidepressants elevates the risk of dementia. Objective:This study aims to investigate the putative association of antidepressants with the risk of dementia. Methods:We conducted a population-based self-controlled case series analysis of older people with dementia and taking antidepressants, using territory-wide medical records of 194,507 older patients collected by the Hospital Authority of Hong Kong, to investigate the association between antidepressant treatment and the risk of developing dementia in older people. Results:There was a significantly higher risk of being diagnosed with dementia during the pre-drug-exposed period (incidence rate ratio (IRR) 20.42 (95% CI: 18.66–22.34)) compared to the non-drug-exposed baseline period. The IRR remained high during the drug-exposed period (IRR 8.86 (7.80–10.06)) before returning to a baseline level after washout (IRR 1.12 (0.77–1.36)). Conclusion:The higher risk of dementia before antidepressant treatment may be related to emerging psychiatric symptoms co-occurring with dementia, which trigger medical consultations that result in a decision to begin antidepressants. Our findings do not support a causal relationship between antidepressant treatment and the risk of dementia.

Keywords: Alzheimer’s disease, antidepressants, causal associations, dementia, self-controlled case series studies

DOI: 10.3233/JAD-200875

Journal: Journal of Alzheimer's Disease, vol. 78, no. 2, pp. 735-744, 2020