Introduction: Previous observational studies have associated benzodiazepine use with an increased risk of dementia. However, limitations in the study methods leave questions unanswered regarding the interpretation of the findings.
Methods: A case-control analysis was conducted using data from the UK-based Clinical Practice Research Datalink (CPRD). A total of 26,459 patients aged ≥65 years with newly diagnosed Alzheimer's disease (AD) or vascular dementia (VaD) between 1998 and 2013 were identified and matched 1:1 to dementia-free controls on age, sex, calendar time, general practice, and number of years of recorded history. Adjusted odds ratios (aORs) were calculated with 95% confidence intervals (CIs) of developing AD or VaD in relation to previous benzodiazepine use, stratified by duration and benzodiazepine type.
Results: The aOR (95% CI) of developing AD for those who started benzodiazepines <1 year before diagnosis was 2.20 (1.91-2.53), and fell to the null for those who started between 2 and <3 years before [aOR 0.99 (0.84-1.17)]. The aOR (95% CI) of developing VaD for those who started benzodiazepines <1 year before diagnosis was 3.30 (2.78-3.92), and fell close to the null for those who started between 3 and <4 years before [aOR 1.16 (0.96-1.40)]. After accounting for benzodiazepine use initiated during this prodromal phase, long-term use of benzodiazepines was not associated with an increased risk of developing AD [aOR 0.69 (0.57-0.85)] or VaD [aOR 1.11 (0.85-1.45)].
Conclusion: After taking a prodromal phase into consideration, benzodiazepine use was not associated with an increased risk of developing AD or VaD.