Background: Recently, the LIfestyle for BRAin health (LIBRA) index was developed to assess an individual's prevention potential for dementia. Objective: We investigated the predictive validity of the LIBRA index for incident dementia in midlife, late life, and the oldest-old. Methods: 9,387 non-demented individuals were recruited from the European population-based DESCRIPAstudy.An individual'sLIBRAindexwas calculated solely based on modifiable risk factors: depression, diabetes, physical activity, hypertension, obesity, smoking, hypercholesterolemia, coronary heart disease, and mild/moderate alcohol use. Cox regression was used to test the predictive validity of LIBRA for dementia at follow-up (mean 7.2 y, range 1 16). Results: In midlife (55 69 y, n = 3,256) and late life (70 79 y, n = 4,320), the risk for dementia increased with higher LIBRA scores. Individuals in the intermediate- and high-risk groups had a higher risk of dementia than those in the low-risk group. In the oldest-old (80 97 y, n = 1,811), higher LIBRA scores did not increase the risk for dementia. Conclusion: LIBRA might be a useful tool to identify individuals for primary prevention interventions of dementia in midlife, and maybe in late life, but not in the oldest-old.