As the world’s life span has been expanding consistently over the last one hundred years due to public health improvements and antibiotics, so has the number of older people, both in absolute figures and as a percentage of the population. In the US, people older than sixty-five now account for 16 percent of the population and consume one-third of all prescription medications. In fact, 20 percent of people over the age of sixty-five are taking at least five different medications.
