09/10/2014 12:39 EDT | Updated 11/10/2014 05:59 EST

Alzheimer's risk raised with use of anxiety, sleeping pills: study

Long-term use of pills for sleep problems and anxiety could increase an elderly person’s chance of getting Alzheimer’s disease by up to 51 per cent, suggests a new study by Canadian and French researchers.

The team, which included scientists from the University of Bordeaux in France and the University of Montreal, tracked 8,890 people over the age of 65 living in Quebec.

All the subjects were members of the province’s drug plan and were analyzed from Jan. 1, 2000 to Dec. 31, 2009.

Researchers monitored which subjects used of benzodiazepines — medications commonly prescribed to treat anxiety or sleeplessness — and which were diagnosed with Alzheimer's. 

The study, published in the British Medical Journal, discovered that:

- 1,796 people of the subjects were diagnosed with Alzheimer’s within six years of the study.

- When compared with the non-Alzheimer's control group, past use of benzodiazepines for three months or more was associated with a 43 to 51 per cent higher risk of getting Alzheimer’s. 

- Longer use of benzodiazepines led to higher risk.

Researchers say benzodiazepines are “valuable tools" for managing anxiety and insomnia but should be used in “short duration and not exceed three months.”

The study also took into account that symptoms such as anxiety, depression and sleeplessness often indicate the early stages of dementia, but researchers concluded that their results were not altered greatly when adjusted for these symptoms.

In the end, the team said it is “crucial to encourage physicians to carefully balance the benefits and risks” when treating elderly patients with benzodiazepines.

In 2011, an estimated 747,000 Canadians were living with Alzheimer’s or other forms of dementia. By 2031, it is estimated that 1.4 million Canadians will have dementia, costing the Canadian economy nearly $300 billion per year, according to the latest government statistics.