Association between concurrent antidepressant and hypnotic treatment and the risk of dementia: A nationwide cohort study

Objective: This study aimed to investigate the risk of dementia among subgroups of patients receiving concurrent antidepressant and hypnotic treatment, antidepressants alone, and hypnotics alone. Methods: Multivariate Cox proportional hazards regression models were used to determine the effects of anti-depressants and hypnotics on dementia risk after adjusting for potential confounders. Results: Compared with the reference group, patients receiving concurrent antidepressant and hypnotic treatment had the highest adjusted hazard ratio (aHR: 2.390, 95% CI: 2.224-2.536; P < 0.001) for all-cause dementia, followed by those receiving antidepressants alone (aHR: 1.919, 95% CI: 1.811-2.012; P < 0.001) and hypnotics alone (aHR: 1.458, 95% CI: 1.397-1.527; P < 0.001). With regard to dementia subtypes, trends similar to those for all-cause dementia were observed for Alzheimer's dementia, vascular dementia and other types of dementia. The sensitivity analysis conducted also found the robustness of findings. Notably, inconsistent findings were observed in subgroup with depression, revealing a null association between concurrent anti-depressant and hypnotic treatment (aHR: 0.496; 95% CI: 0.183-1.343; P = 0.175) or hypnotics alone (aHR: 2.750; 95% CI: 0.797-9.482; P = 0.102) and the risk of dementia, and a negative association between anti-depressants alone (aHR: 0.351; 95% CI: 0.130-0.942; P = 0.032) and the risk of dementia. Conclusion: A null or negative association was observed between concurrent antidepressant and hypnotic treatment, antidepressants alone, hypnotics alone, and the dementia risk in the subgroup of patients with depression, suggesting the absence of an association between dementia risk and antidepressants alone or hypnotics alone.