According to the World Health Organization (WHO), approximately 57 million people had dementia globally in 2021. Although the major risk factor of dementia is increased age, recent studies have indicated that psychosocial factors also play a key role in dementia risk. One example of a psychosocial factor is optimism, which is associated with improved cognitive health and healthy ageing. This is likely due to its role in reducing cortisol levels and preventing chronic inflammation, which is a known driver of disease. A few studies have assessed the effects of optimism on dementia risk, but none have assessed the effects in a diverse cohort of men and women for a follow-up period of longer than ten years. In research published in March 2026 in the Journal of the American Geriatrics Society, Säde Stenlund and colleagues utilised data from a nationally representative cohort study of adults aged 50 years and older, known as the Health and Retirement Study (HRS), to assess the risk of dementia development based on optimism levels over a 14-year follow-up period. Individuals with higher levels of optimism were reported to have lower risks of dementia, with every one-standard deviation increase in optimism being associated with a 15% lower risk of developing dementia, even after adjusting for age, sex, race and ethnicity, education, depression, and major health conditions.
To derive dementia status, this study analysed data of HRS dementia-free participants aged 70 years and older from 2006–2020 who had data on demographic factors, cognitive assessments, physical functioning / health, and social engagement acquired from in-person or telephone interviews. This data was used for a dementia algorithm which predicted dementia status as either “yes” or “no”. Optimism was self-reported by participants via the Life Orientation Test-Revised, whereby participants rated statements, ranging from 1 (“strongly disagree”) to 6 (“strongly agree”). After coding, the scores ranged from 6–36, with higher scores reflecting higher optimism. A total of 9,071 dementia-free individuals were recruited into the study, 3,027 of which developed dementia over the follow-up period. Optimism was associated with a statistically significant decreased risk of developing dementia, with every one-standard deviation increase in optimism score corresponding with a 15% reduced risk. Additionally, the quartile with the highest optimism scores had a 38% lower risk of developing dementia compared to the quartile with the lowest optimism scores. These trends were observed even after adjusting for age, sex, race and ethnicity, education, depression, and major health conditions.
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The study by Stenlund and colleagues provides evidence that optimism acts as a protective factor against dementia. However, dementia status was identified via an algorithm. As such, future studies should consider assessing the effects of optimism on actual diagnosed dementia cases to maintain validity. Additionally, as this was an observational study, unidentified confounders may be contributing to this relationship. GlobalData epidemiologists forecast that in the US, Diagnostic and Statistical Manual of Mental Disorders IV (DSM IV)-diagnosed prevalent cases of Alzheimer’s disease in men and women, ages 65 years and older, will increase from 1.3 million cases in 2026 to 1.8 million cases in 2033.
