According to a study in the British Medical Journal, benzodiazepine use is associated with a significantly increased risk of developing Alzheimer’s disease. Some experts have argued in news reports that the findings simply indicate that people with Alzheimer’s are more often prescribed benzodiazepines. However, the study authors have pointed out that there appears to be a dose-dependent response occurring.
The team of Quebec-based researchers studied six years of records for 1,796 elderly people with a first diagnosis of Alzheimer’s and 7,184 controls, and found that the longer people took benzodiazepines for, the higher their risk of developing Alzheimer’s was.
“Those who took the cumulative equivalent of daily doses for three to six months over a five-year period were roughly 32% more likely than those who took none to develop Alzheimer’s,” reported the Los Angeles Times. “Those who took the cumulative equivalent of a full daily dose for more than six months were 84% more likely to do so.”
The director of Alzheimer’s Research UK told BBC News that, “This study shows an apparent link between the use of benzodiazepines and Alzheimer’s disease although it’s hard to know the underlying reason behind the link. One limitation of this study is that benzodiazepines treat symptoms such as anxiety and sleep disturbance, which may also be early indicators of Alzheimer’s disease.”
The president of the European College of Neuropsychopharmacology told BBC News that the findings “could mean that the drugs cause the disease, but [the findings are] more likely to mean that the drugs are being given to people who are already ill.”
However, the researchers themselves felt the case for causation was strong. “Benzodiazepine use is associated with an increased risk of Alzheimer’s disease,” they wrote. “The stronger association observed for long term exposures reinforces the suspicion of a possible direct association, even if benzodiazepine use might also be an early marker of a condition associated with an increased risk of dementia.”
Benzodiazepine use and risk of Alzheimer’s disease: case-control study (Billioti de Gage, Sophie et al. British Medical Journal. September 9, 2014. doi: http://dx.doi.org/10.1136/bmj.g5205)
Anxiety and sleeping pills ‘linked to dementia’ (BBC News, September 9, 2014)
Drugs used for anxiety, sleep are linked to Alzheimer’s disease in older people (Los Angeles Times, September 9, 2014)