There is some evidence suggesting that the use of Benzodiazepines like Ativan, Xanax, Clonazepam, Valium, is associated with excess risk for dementia; however, benzodiazepines are sometimes prescribed for prodromes of dementia, (e.g., anxiety, insomnia). In this case-control study, investigators examined the association between exposure to benzodiazepines and risk for developing Alzheimer disease (AD).
The association was stronger for long-acting benzodiazepines ( Valium) than for short-acting benzodiazepines (Xanax).

Billioti de Gage S et al. BMJ 2014 Sep 9.