HMM: Do Anxiety Pills Have a Dark Side? Research Reveals Dementia Risks. From reading the article, though, it seems that — as I have suspected for a while — the anxiety is associated with dementia, and the use of benzodiazepenes is more of a marker for anxiety than a cause. I suspect the same is true of Benadryl, which has shown a similar association with dementia, since lots of people use Benadryl as an OTC anxiety/sleep med.