Researchers from the Harvard University in the US and the University of Bordeaux in France found that elderly who used benzodiazepines - which include temazepam and diazepam - are at a significantly higher risk of dementia.
The team discovered that over-65s who had taken the drugs within the last 15 years were 50 per cent more likely to get dementia, the Daily Mail reported.
The pills work by changing the way messages are transmitted to the brain, which induces a calming effect.
However, scientists believe that at the same time they may be interfering with chemicals in the brain known as neurotransmitters, which may be causing dementia.
The study involved 1,063 men and women over the age of 65 for a period of 20 years in south west France. Initially none of the participants had dementia and no one was taking benzodiazepines.
The researchers followed them up after 15 years and found that 253 had developed dementia. They worked out that out of 100 not taking the drug, 3.2 would be expected to get the illness.
However, among 100 patients on these drugs, 4.8 would get dementia - a significantly higher proportion. The patients had taken the pills at least once
