One of the most significant changes in our world today is the shift in population demographics. The people of
the world are getting older. In 2000, there were 600 million people aged 60 and over; there will be 1.2 billionbby 2025 and 2 billion by 2050.1

By 2050, the number of older persons in the world will exceed the numberof young for the first time in history.2

People are living longer today for several reasons including advances in medical science, technology, health care, nutrition, and sanitation. An important consequence of this progress is that those aged 80 or older are the fastest growing age group in the world.3

Although this larger older population is in better health than
ever before, they have some modified abilities. Sensory, cognitive, and physical health, mobility and dexterity changes are prevalent among older persons, and raise many questions about the ways that we think
about human-environment interaction.