The true picture could be even worse because the latest figures rely on people reporting their own use of psychiatric medications, says Thomas Moore from the Institute for Safe Medication Practices based in Virginia.
Around 80 per cent of the users are taking the drugs long-term, even possibly as a 'prop' to help them through life, which goes against strict prescribing guidelines. Benzodiazepines have a long history of dependency problems, and withdrawal and 'rebound' symptoms, for instance. Some people are also taking more than one psychiatric drug.
The researchers analysed data from the 2013 Medical Expenditure Panel Survey to calculate the percentage of American adults who were taking an antidepressant, a sedative or hypnotic, or an antipsychotic. The most common drug was the antidepressant, which was being taken by around 12 per cent of the users.
Overall, one in six adults was taking a prescription psychiatric drug, a figure that's far higher than the 11 per cent suggested by earlier research.