By Lucy Piper, Senior medwireNews Reporter

Benzodiazepines, commonly used by older adults to manage sleep, anxiety and depressive disorders, do not increase the risk of dementia or hasten cognitive decline, study findings show.

The results, published in the BMJ, show that a high use of benzodiazepines, equivalent to about a year of daily use, did not contribute to the development of dementia in 797 participants, out of 3434, who developed the condition over an average of 7.3 years.

The findings therefore do not support a causal association between cumulative benzodiazepine use and dementia, say the researchers, led by Shelly Gray (University of Washington, Seattle, USA), but they still advise against their use in older adults to avoid other adverse health outcomes.

The participants, aged at least 65 years and free of dementia at study enrolment, completed the cognitive abilities screening instrument every 2 years. Among the 797 (23.2%) who developed dementia, 637 (79.9%) were diagnosed with Alzheimer’s disease.

Benzodiazepine use, determined from computerised pharmacy data, consisted of the total standardised daily doses (TSDDs) dispensed over a 10-year period – a moving window that rolled forward during follow-up.

Patients with the highest benzodiazepine use of 121 or more TSDDs were no more likely than non-users to develop dementia or Alzheimer’s disease, with hazard ratios of 1.07 and 0.95, respectively, after adjusting for factors such as age, gender, body mass index, smoking, exercise and cardiovascular risk factors.

Contrary to expectations, the risk of dementia was slightly higher among low (1–30 TSDDs) and moderate (31–120 TSDDs) users, compared with non-users, with respective hazard ratios of 1.25 and 1.31, but the researchers say that this small increased risk “could represent treatment of prodromal symptoms.”

Levels of cognitive decline were also similar irrespective of benzodiazepine use, with the decline in patients with the highest use 0.002 points slower than that of non-users. And there was no difference in cognitive decline between patients who had used benzodiazepines recently versus not for 6 months or more before entering the study.

“Overall, our pattern of findings does not support the theory that cumulative benzodiazepine use at the levels observed in our population is causally related to an increased risk for dementia or cognitive decline”, say Gray and colleagues.

But they add that “given the mixed evidence regarding benzodiazepines and risk of dementia and that these drugs are associated with many adverse events, healthcare providers are still advised to avoid benzodiazepines in older adults to prevent important adverse health outcomes, withdrawal, and dependence.”

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