In all phases of life, people face decisions with important consequences. Weighing options involves using cognitive resources to assess valence, delay, and risk to achieve a desired outcome. Value-based decision-making changes over the lifespan, but studies disagree on the extent, domains, and mechanisms of this change. We assessed delay discounting, risk aversion for probabilistic gains, risk seeking for probabilistic losses, loss aversion as well as cognitive abilities, and processing noise in 86 young (25–38 years) and 93 older (63–76 years) adults. We tested whether decision-making differed between age groups and whether differences were mediated by cognitive abilities or processing noise as measured by reaction time variability and decision inconsistency. Older adults showed steeper delay discounting (p =.003) and trended towards more risk aversion for gains (p =.071). Age groups did not differ in risk seeking for losses or loss aversion. Lower decision consistency and better spatial working memory mediated older adults’ steeper delay discounting. The relationship between delay discounting and age persisted when controlling for both mediators, suggesting robust age differences in delay discounting. This persistent age difference implies mechanisms beyond noise or cognitive parameters, such as changing life circumstances or limited future perspective.