If you think our roads are made more dangerous by teenagers driving while high on illicit drugs, think again. For kids, read the over-50s, and they're high on multiple prescription drugs.
It's down to 'polypharmacy', where more than one prescription is written out at the same time. The average over-50 could be taking around five different prescription drugs, and it's starting to show up in the statistics for road fatalities.
The number of fatalities of drivers who were taking multiple prescription drugs has doubled in the past 17 years, say researchers from the University of Nebraska. It's now outnumbering road deaths while under the influence of cannabis.
The trend is only going to increase, say the researchers, as more than 90 per cent of Americans aged 65 years and older are now taking one or more prescription drugs. It's a new phenomenon, and one that law enforcers are unable to deal with, although 42 of America's 50 states have prescription drug monitoring programmes in place.
(Source: University of Nebraska Medical Centre)