Globe and Mail - Are helmets good for your brain? It depends how you roll

Bike helmets have been a flashpoint of scientific controversy since the 1980s. […] few experts doubt that you’re better off with a helmet if you’re in a bike accident. But helmet laws and public safety campaigns promoting helmet use also discourage people from cycling in the first place, he argues, leaving the remaining cyclists more vulnerable to cars. This is sometimes dubbed the “safety in numbers” argument. […]

A Norwegian study that will be published later this year in the journal Risk Analysis investigated this effect by asking 35 cyclists to bike down a steep hill with and without a helmet. Habitual helmet-wearers did slow down when they were asked to remove their helmets, but non-helmet wearers didn’t speed up at all when they donned a helmet.

This ambiguous result is typical of risk homeostasis studies. In an earlier paper, McGill University researchers interviewed 394 children who’d sustained injuries in activities such as cycling, hockey and skiing, slightly more than half of whom had used protective equipment. They concluded that risk homeostasis “does not seem to be a significant reality,” at least among children.