Theyarethemiraclepillsthatshouldn'treallyworkatall.Placeboscomeinallshapesandsizes,buttheycontainnoactiveingredient.Nowtheyarebeingshowntohelptreatpain,depressionandevenalleviatesomeofthesymptomsofParkinson'sdisease.Horizonexploreswhytheywork,andhowwecouldallbenefitfromthehiddenpoweroftheplacebo.