Benzodiazepines are commonly used for behavioral and psychiatric symptoms of dementia, despite their numerous adverse effects and the lack of evidence regarding their efficacy in this context. We studied longitudinal benzodiazepines exposure in incident cases of Alzheimer's disease and related syndromes (ADRS) in France. We used a cohort of incident ADRS patients identified in 2012 within the national health data system. Benzodiazepines exposure was measured 1 year before, to 5 years after ADRS identification. Quarterly benzodiazepines prevalence and incidence were computed. We identified factors associated with long half-life benzodiazepines initiation. A total of 106 508 subjects were included. Quarterly benzodiazepines prevalence was stable (around 25%) but we saw an important decrease in long half-life benzodiazepines compensated by an increase in short half-life benzodiazepines. In most benzodiazepine initiations, the first episode lasted less than 3 months. Factors associated with initiating a long half-life benzodiazepine were young age, male gender, no registration with ADRS as a long-term disease, having consulted an ADRS specialist, antipsychotic reimbursement before the index date, no admission in nursing home. Prevalence of benzodiazepines use remains high in subjects with ADRS despite guidelines for their avoidance. However, indicators regarding benzodiazepine initiations (duration, benzodiazepine type) suggest some caution in their use.