With continued population aging, the loss of cognitive function among some older Americans foreshadows a potentially enormous social and economic burden. In this interview, Kenneth Langa, University of Michigan School of Medicine and Institute for Social Research, discusses cognitive impairment and its causes, trends, and effects in the United States. He warns that certain trends may adversely affect the brain health of Americans, especially rising obesity rates and a consequent increase in diabetes, which is also associated with declining cognitive function among older adults.