A popular anti-anxiety drug has been linked with an increased risk of dementia in pensioners, according to new research published late Thursday. Patients over the age of 65 who start taking benzodiazepines, also known as benzos, have a 50% increased chance of developing dementia within 15 years compared with people who had never used the drug, according to the study that was published in the website of the British Medical Journal. Researchers from the University of Bordeaux, France, warned that \"indiscriminate widespread use\" of the drugs, which are also used to treat insomnia, should be cautioned against; the drug is widely used in many countries. In France, 30% of people over the age of 65 take benzodiazepines. Many administer the drug for long periods despite guidelines suggesting it should only be used for a few weeks. The research examined 1,063 people with an average age of 78 over two decades who had never taken the drug before and were all free from dementia. They found that 95 patients started taking benzodiazepine during the study; after a 15-year follow-up, 253 people developed dementia. Of these, 30 had begun to take the drugs between three and five years into the study. \"In this large, 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, new use of benzodiazepines was associated with a significant, approximately 50% increase in the risk of dementia,\" the authors wrote. Dr Eric Karran, director of research at Alzheimer\'s Research UK, added \"Long-term population studies are invaluable for helping us to understand how our environment and life events may influence our risk of dementia, but it can be incredibly difficult to tease out the real cause behind these associations.