Benzodiazepines: dementia in the elderly?

About twenty benzodiazepines and related drugs, such as zolpidem and zopiclone, are used to treat sleep dis- orders and anxiety, and also as anti- convulsants.Their short-term adverse effects include confusion and cogni- tive disorders that regress only slow- ly after treatment withdrawal, especial- ly in elderly patients. Questions have been raised as to persistent cognitive effects in case of long-term benzo- diazepine exposure. A case-control study of 1796 patients over 66 years of age showed that benzodiazepine exposure 5 to 10 years previously was statistically significant- ly more frequent among those who developed Alzheimer's disease. Five other epidemiological studies provided similar results. However, some studies showed no relation with the duration of exposure or the cumu- lative dose; this is an argument against a causal relationship between benzodiazepine use and dementia. These studies provide only weak evidence and thus fail to establish a causal relationship. In addition, early symptoms of dementia can cause anx- iety, which may lead to benzodiazepine prescription in the period preceding diagnosis.The results of these studies do not, however, rule out a long-term risk of persistent cognitive impair- ment. In practice, the known adverse effects of benzodiazepines are a suf- ficient reason to avoid these drugs, especially in elderly patients. The pos- sibility of irreversible cognitive impair- ment is another reason not to pre- scribe them.