An estimated 42% of Americans over the age of 55 are expected to develop dementia at some point, but there’s a bright side to that dark statistic. Researchers from the Harvard T. H. Chan School of Public Health are adding to growing evidence that one particular personality trait can lower the risk of dementia — optimism. “Together with previous studies, our findings provide support for the possibility that optimism causally contributes to cognitive health and may be considered an asset for