Drugs in the benzodiazepine family have long been used to treat anxiety and sleep problems. They can cause a bit of a brain hangover the next day. Experts have long assumed that people’s heads would clear once they stopped taking the drug. That may not be the case. In a study published last night by the journal BMJ, a team of researchers from France and Canada linked benzodiazepine use to an increased risk of being diagnosed with Alzheimer’s disease. In the study, the greater a person’s cumulative dose of benzodiazepines, the higher his or her risk of Alzheimer’s. Taking a benzodiazepine for less than three months had no effect on Alzheimer’s risk. Taking the drug for three to six months raised the risk of developing Alzheimer’s by 32%, and taking it for more than six months boosted the risk by 84%. People taking a long-acting benzodiazepine were at greater risk than those on a short-acting one.