Association of Benzodiazepine and Anticholinergic Drug Usage With Incident Dementia: A Prospective Cohort Study of Community-Dwelling Older Adults.

OBJECTIVES: To examine the association of benzodiazepines and anticholinergic drug usage with the risk of dementia.

DESIGN: Prospective cohort study.

SETTING: Community-dwelling participants, recruited in family practices in the Netherlands.

PARTICIPANTS: In total, 3526 individuals aged 70 to 78 years without dementia within 116 participating family practices.

METHODS: Information about drug use was reported at baseline and at 2-year follow-up and was cross-checked with the participants' electronic health records. Anticholinergic drug exposure was defined by the anticholinergic cognitive burden score. Participants were evaluated for dementia during follow-up assessments every 2 years, supplemented by information from electronic health records and the National Death Registry.

RESULTS: During a median follow-up of 6.7 years, dementia developed in 233 participants (7%). In participants using benzodiazepines, 6% developed dementia vs 7% in nonusers [hazard ratio (HR) 0.71, 95% confidence interval (CI) 0.58-1.07]. Persistent usage of benzodiazepines at baseline and after 2-year follow-up did not substantially alter the point-estimate (HR 0.60, 95% CI 0.34-1.10). Use of any anticholinergic drugs was not associated with incident dementia (HR 1.01, 95% CI 0.50-1.10). Dementia risk was significantly increased for participants with persistent drug use with a high anticholinergic cognitive burden score (HR 1.95, 95% CI 1.13-3.38) though this effect was absent when excluding participants taking antidepressants or antipsychotics (HR 0.42, 95% CI 0.06-3.01).

CONCLUSIONS AND IMPLICATIONS: In our study population, benzodiazepine usage was not associated with an increased risk of dementia. Persistent high anticholinergic exposure was associated with an increased risk of dementia over 6 years of follow-up, and this association was driven by antidepressant or antipsychotic drug use, suggesting confounding by indication bias contributing to this. Although this observation could ameliorate prescription hesitance, healthcare providers are still advised to carefully weigh the potential benefits of benzodiazepines and anticholinergic drugs against the associated adverse health outcomes.