If you’re like most psychiatrists, you get your fair share of older folks who come into the office complaining of difficulties with sleep or with significant symptoms of anxiety.

In many of these cases, after an adequate workup, it’s not unusual to use at least a short course of benzodiazepines such as Restoril or Ativan. We’ve known for some time that we need to be particularly careful about using benzos in older patients because of the increased fall risk (Hill KD & Wee R, Drugs Aging 2012;29(1):15–30) but we now have increasing evidence that these meds may increase the risk of Alzheimer’s disease (AD).

The latest study to document this association is the largest and most convincing one yet. Researchers looked through health insurance data from Canada, and located the records of 1,796 patients who had developed AD. They ascertained what percentage of these patients had used benzodiazepines over the past six years. They then collected records for a comparison group of 7,184 elderly patients who were cognitively normal and extracted the same benzodiazepine data.

The question was whether patients with AD were more likely to have used benzos than the patients without AD. That answer was yes: those with a history of benzo use had a 51% increased risk for AD. Even when they adjusted for potential confounders such as depression, anxiety, and insomnia, the results did not change by much—there was still a 43% increased risk.

They also found that the higher the number of doses used, the higher the AD risk. For example, looking at only the group who used fewer than 180 doses, the risk was increased by 84%. On the other hand, patients who used fewer than 90 doses had no increased risk, and the middle group of 90–180 doses had an in between risk. Also, long-acting benzos conferred a higher risk than short-acting benzos (70% vs. 43%) (Billioti de Gage S et al, BMJ 2014;349:g5205).

Dr. Carlat’s Verdict: While this is not the first study to show an association between benzo use and dementia, it is the most rigorous study and the first to show a correlation between cumulative dose exposure and risk of AD. Correlation does not equal causation, but the results do encourage us to use common sense in prescribing benzos to the elderly—minimize the dose and stick with shorter acting agents when possible.