As in the earlier trial, half the participants will be given the drug, the other half will get what is known as a placebo - an inactive substance.

Half of the participants were given the drug, the other half got what is known as a placebo - an inactive substance.

Half get the drug, half get what is known as a placebo - an inactive substance.

That's the phenomenon in which people's symptoms improve after taking an inactive substance simply because they believe the treatment will work.

Patients who received injections of an inactive substance often reported pain relief, too.