A large study in the United States has found that higher levels of optimism in older adults are linked to a significantly lower risk of developing dementia. For every six-point increase on a standard optimism scale, participants experienced a 15 percent reduction in risk. The association remained strong even after accounting for age, gender, ethnicity, education, depression, chronic illness, mental health, and lifestyle factors, and persisted when early cases were excluded to reduce bias.

Researchers from Harvard University analyzed data from 9,071 cognitively healthy adults aged 50 and older who were followed for up to 14 years. More than 3,000 participants developed dementia during that time, but rates were consistently lower among those who reported greater optimism at the start of the study. The findings were consistent across racial and ethnic groups.

The authors described optimism as a protective psychosocial factor that may support healthy aging and cognitive resilience. They suggested that optimistic individuals may be more likely to exercise regularly, avoid smoking, and engage in other healthy behaviors that benefit brain health. While diet, physical activity, and social engagement remain essential, cultivating a positive outlook may help delay or reduce the risk of dementia.