A recent review of the research found that benzodiazepine use may have long-term effects on memory and increase the risk for dementia. The study, published in CNS Drugs, calls for greater awareness of these potential risks among prescribers and more research on the mechanisms involved.
Pariente, A., de Gage, S. B., Moore, N., & Bégaud, B. (2015). The Benzodiazepine–Dementia Disorders Link: Current State of Knowledge. CNS drugs, 1-7. (Abstract)