Short term adverse effects of benzodiazepines on cognition is well known. These agents are widely used , often for long periods,especially in elderly patients.Studies focusing on the association between benzodiazepine use and dementia or cognitive decline in elderly people have shown conflicting results. The possibility of reverse causation was a limitation of previous studies. ( ie Those who manifest the prodromal symptoms of dementia (insomnia,depression, and anxiety) were prescribed benzodiazepines)
French researchers ,Sophie Billioti de Gage, Bernard Begau and their team , have studied 3777 community people aged 65 years and over . This is part of a large prospective cohort study (PAQUID cohort study). Information up to the 20 year visit is available.1063 participants were eligible to enter this study.
At baseline and at each follow-up visit, trained neuropsychologists collected detailed information on personal characteristics, sociodemographics, life habits, health conditions, drug use, functional abilities, depressive symptoms, and cognition during face to face interviews. They introduced an observation period of three to five years before the start of follow-up, to ensure that participants were free from dementia at the five year follow-up visit. Participants did not use benzodiazepines at least up to the three year follow-up visit.
During the 15 year follow-up, 253 (23.8%) cases of dementia were confirmed—30 (32%) in benzodiazepine users and 223 (23.0%) in non-users.The incidence rate of dementia during the 15 year follow-up was 4.8 per 100 person years in the exposed group compared with 3.2 per 100 person years in the non-exposed group. Use of benzos is thus associated with approximately 50% increase in the risk of dementia.
This prospective, population based study of elderly people who were free of dementia and did not use benzodiazepines until at least the third year of follow-up showed that new use of benzodiazepines was associated with a significant, approximately 50% increase in the risk of dementia. This result remained stable after adjustment for potential confounding factors.
Authors recommend that physicians should carefully assess the expected benefits of the use of benzodiazepines in the light of these adverse effects. if necessary , prescription should be limited to a few weeks. Uncontrolled chronic use of benzodiazepines in elderly people should be strongly discouraged.
It is important to note that Z drugs are also included in the benzo group in this study.
Summary of the article: Benzodiazepine use and risk of dementia: prospective population based study. BMJ 2012; 345 doi: 10.1136/bmj.e6231 (Published 27 September 2012)