Primarily indicated for treating the symptoms of anxiety and sleep disorders over short periods, benzodiazepines are widely prescribed in developed countries. In France, 30% of people aged 65 years and over use benzodiazepines [1Fourrier A., et al. Benzodiazepine use in an elderly community-dwelling population: characteristics of users and factors associated with subsequent use Eur J Clin Pharmacol 2001 ;  57 : 419-425 [cross-ref]

Cliquez ici pour aller à la section Références]. Some studies found an increased risk of dementia or cognitive impairment in benzodiazepines users [2Gallacher J., et al. Benzodiazepine use and risk of dementia: evidence from the Caerphilly Prospective Study (CaPS) J Epidemiology Community Health 2012 ;  66 : 869-873 [cross-ref]

Cliquez ici pour aller à la section Références]. Moreover, the aging of the population should lead to a sharp rise of the number of demented subjects. To reduce the burden of dementia, interventions targeting dementia risk factors could be proposed, but the association between most of these risk factors and mortality makes it difficult to anticipate the potential impact of such interventions. Assuming a causal effect of benzodiazepines on dementia risk, the main objective of this work is to evaluate consequences of benzodiazepine consumption reduction on various measures of dementia burden.

A three-state model called illness-death model was used to estimate the dementia incidence rate and the over-risk of death for demented subjects [3Wanneveich M., et al. Impact of intervention targeting risk factors on chronic disease burden Stat Methods Med Res 2016 ; 17[0962280216631360.pmid:26988925].

Cliquez ici pour aller à la section Références]. National demographic projections provided general mortality rates and population at 65 years. We assumed that a subject who used benzodiazepines for more than 6 months continuously after age 65 remained at higher risk of dementia until the end of his/her life. A Monte Carlo algorithm with a discrete time model was implemented to make projections for the life expectancies with and without dementia, the age at dementia onset, the lifelong probability of dementia and the prevalence of dementia. The methodology took into account the mortality trend over calendar time and age in both healthy and demented subjects. The method was used to provide projections for dementia in 2040 under two scenarios, either division by two or suppression of benzodiazepines use from 2020.

We estimated that more than 2.8 million subjects will live with dementia in France in 2040. Dividing the benzodiazepine consumption by two from 2020 should led to 5.5% fewer demented cases in France in 2040. With the extreme scenario of suppression of benzodiazepine use from 2020, the number of cases would be reduced by 12.8%. Moreover, the life expectancy without dementia for 65-years-old women in 2040 was estimated at 21.85 years without intervention versus 22.47 years if benzodiazepine consumption was divided by two and 23.33 years with a removal of benzodiazepine use in 2020. In the same way, the lifelong probability of dementia was higher without intervention. For example, this estimated probability without intervention was 59.07% for non-demented men 65-years-old in 2040 versus 50.72% if benzodiazepine use was null from 2020.

Assuming a causal relationship, the proposed methodology showed that a decrease in benzodiazepine consumption could reduce dementia burden in the future. The method could be used for evaluating scenarios of change for other drugs or risk factors for any chronic diseases.