Optimism Linked to 15% Lower Dementia Risk in 14-Year Study

Apr 17, 2026

Harvard T.H. Chan School of Public Health researchers led by Säde Stenlund found that higher optimism levels are associated with a 15% reduction in dementia risk over 14 years, according to a study published April 8 in the Journal of the American Geriatrics Society. The research analyzed data from more than 9,000 cognitively healthy older U.S. adults between 2006 and 2020, with participants completing optimism assessments every four years. Each 1-standard deviation increase in optimism—roughly the difference between average and noticeably above-average optimism—corresponded to the 15% risk reduction. Researchers suggest optimistic individuals may benefit through healthier behaviors including exercise, better stress management, cognitive engagement, and stronger social connections, and emphasize that optimism can be cultivated through practices like daily gratitude lists.

Optimism's protective effect against dementia in 14-year study

▪Participants in the Harvard optimism and dementia study were cognitively healthy at baseline.
▪More than 9,000 cognitively healthy seniors completed assessments of their dispositional optimism every four years in the Harvard optimism and dementia study.
▪Every 1-standard deviation increase in a participant's optimism level score was associated with a 15% lower risk of developing dementia during the study period.
▪A study led by Harvard T.H. Chan School of Public Health found that higher levels of optimism were linked with decreased risk of dementia.
▪Säde Stenlund, research associate in the Department of Social and Behavioral Sciences at Harvard T.H. Chan School of Public Health, led the optimism and dementia study.
▪The Harvard T.H. Chan School of Public Health optimism and dementia study was published April 8 in the Journal of the American Geriatrics Society.
▪The Health and Retirement Study is a nationally representative sample of older U.S. adults.
▪The Harvard optimism and dementia study used data collected between 2006 and 2020 by the Health and Retirement Study.
▪A 1-standard deviation increase in optimism is roughly the difference between someone with average optimism and someone who is noticeably more optimistic than average.

Mechanisms linking optimism to brain health

▪Optimistic people are likelier to maintain strong social connections, which can help protect brain health.
▪Optimistic people are likelier to exercise and practice other healthy behaviors that can help protect brain health.
▪Optimistic people are likelier to manage stress well, which can help protect brain health.

Cultivating optimism as a learnable skill

▪Keeping a gratitude list is a simple practice that can help cultivate optimism.
▪The Harvard optimism and dementia study findings could inform dementia prevention initiatives.
▪Säde Stenlund recommended taking a moment each day to jot down three things to be grateful for as a habit that can help cultivate positivity.
▪Optimism is not just an inborn trait and can be learned and nurtured.

Perspective of Harvard T.H. Chan School of Public Health researchers

▪Säde Stenlund views optimism as a learnable skill rather than solely an inherited personality trait.
▪The Harvard researchers propose that simple daily gratitude practices could help individuals develop more optimistic outlooks.