Conditioning can make placebo affect persist after knowing it’s fake

The placebo effect is real – even if you know the treatment you’ve been given has no medical value, research has concluded.

Scientists found patients given a fake painkiller continued to feel benefits from it after they were told it was not genuine.

But there was a catch. For in order to feel these effects, the subjects had to be conditioned into thinking the treatment was real – and given enough time for this belief to become ingrained.

Those told it was fake after just one session did not continue to experience pain relief, the US study found, but those told after four sessions still felt the benefits.

Senior author Tor Wager, of the University of Colorado Boulder, said: “We’re still learning a lot about the critical ingredients of placebo effects. What we think now is that they require both belief in the power of the treatment and experiences that are consistent with those beliefs.