People 65 and older who begin taking a class of drug used to treat anxiety and insomnia increase their risk of developing dementia in the next 15 years by about 50%, according to a recently released study.

Guidelines suggest that benzodiazepines, drugs like Ativan, Valium and Xanax, should only be used for a few weeks. Yet many people take these drugs for years.

These drugs raise the likelihood of falls in the elderly...

The French study tracked 1,063 people, average age 78, for 20 years. The first 3-5 years were used as an observation period. Then researchers began collecting data on new benzodiazepine use. Over the remainder of the study, 98 people began taking benzodiazepines. By the study's end, there were 253 cases of dementia diagnosed, 30 in benzodiazepine users (32%) and 223 (23%) in non-users. After taking into account the different observation lengths for each individual, the occurrence of dementia was 4.8 per 100 person years in the benzodiazepine users and 3.2 per 100 person years in non-users -- 50% higher in the users.

The study was designed with the initial 3-5 year observation period in order to gather data allowing the researchers to better pinpoint whether taking benzodiazepines was actually causing dementia and was not an unrelated factor. Doing this helped the researchers avoid the kind of thinking that might lead you to decide that since most basketball players are tall, playing basketball must make you tall. For example, depression is known to increase the risk of dementia. If people were prescribed benzodiazepines because of depression, benzodiazepine usage might have absolutely no impact on development of dementia--their usage would be a symptom rather than a cause (known as reverse causation).

The researchers found no such association, which indicates that benzodiazepines were actually causing the increase in dementia seen in the people who were taking them.

The researchers hope that their study, combined with others that suggest these drugs raise the likelihood of falls in the elderly, will influence doctors to limit their prescriptions for these drugs to a few weeks and will also lead to more doctors cautioning their patients about the dangers of taking these drugs on their own or for long periods of time.

The study was published in the British Medical Journal (BMJ).