Music therapist Heather Davidson (left) plays a drum with Claire Diering (right) during a drum circle with patients with Alzheimer's disease at the Copper Ridge Care Centre in Sykesville, Maryland, on October 23, 2009. AFP
Music therapist Heather Davidson (left) plays a drum with Claire Diering (right) during a drum circle with patients with Alzheimer's disease at the Copper Ridge Care Centre in Sykesville, Maryland, onShow more

Why must hope for new dementia drugs carry such a heavy price tag?