Benzodiazepines are an effective treatment for acute anxiety and transient insomnia, but guidelines advise that they should not be prescribed for longer than a few weeks as their long-term use can lead to dependency and falls in older people (amongst other things). The evidence appears compelling and yet benzodiazepines are still widely prescribed in the UK, the US and other countries as a long-term treatment.

Researchers from France have now published a prospective population based cohort study that investigates the association between the use of benzodiazepines and incident dementia.

In 1987, they took a group of 1,063 men and women (average age 78), who were all free from dementia at the start of the study. They followed them up for 20 years (a 5 year long eligibility assessment period and 15 year cohort analysis follow-up) and identified why people started taking benzodiazepines and whether or not this drug use increased their chances of developing dementia.

They adjusted their models for potential confounding factors that are also associated with developing dementia such as age, gender, educational level, marital status, wine consumption, diabetes, high blood pressure, cognitive decline, and depression.

Here’s what they found:

• 253 cases of dementia were confirmed in the 15 year follow-up
• New use of benzodiazepines was associated with an increased risk of dementia (multivariable adjusted hazard ratio 1.60, 95% confidence interval 1.08 to 2.38)
• Sensitivity analysis considering the existence of depressive symptoms showed a similar association (hazard ratio 1.62, 1.08 to 2.43)
• Ever use of benzodiazepines was associated with an approximately 50% increase in the risk of dementia (adjusted odds ratio 1.55, 1.24 to 1.95) compared with never users
• The results were similar in past users (odds ratio 1.56, 1.23 to 1.98) and recent users (1.48, 0.83 to 2.63) but reached significance only for past users.

The authors concluded:

Considering the extent to which benzodiazepines are now prescribed, physicians and regulatory agencies should consider the increasing evidence of the potential adverse effects of this drug class for the general population.

The limitations of this study are:

• The size of the study population was too small to allow for any subgroup analysis of individual benzodiazepines
• The fact that they did not separately adjust for anxiety and sleep disorders
• The exclusion of people who had missing benzodiazepine use data during the 5 year run-in period.

It will be interesting to see if future studies in this area investigate the possible correlations between benzodiazepine dosage or the cumulative length of exposure and dementia.

Link

Billioti de Gage S, Bégaud B, Bazin F, Verdoux H, Dartigues J, Pérès K, Kurth T, Pariente A. Benzodiazepine use and risk of dementia: prospective population based study. BMJ, 2012; 345: e6231 DOI: 10.1136/bmj.e6231

Long term dependence on benzodiazepines is addressed by two new reports. The Mental Elf, 13 May 2011.

Benzodiazepines associated with an increase in falls and fractures in older adults. The Mental Elf, 2 Jul 2011.