Cognitive modifications during ageing can affect decision-making competence (DMC). As this ability is central to the preservation of autonomy, our study aims to investigate how it changes in elderly adults and to determine whether such changes are linked to the deterioration of executive functions and working memory. To this end, 50 young adults and 50 elderly adults were assessed with executive, working memory, and DMC tasks. The latter comprised the Iowa Gambling Task (IGT) and a scenario task based on situations inspired by everyday life, under conditions of both risk and ambiguity. The results revealed lower performances in old than in young adults for the updating, inhibition, and working memory tasks. The IGT failed to distinguish between the two age groups. However, the scenario task did permit such a distinction, with young adults seeking more risky and ambiguous choices than elderly adults. Moreover, updating and inhibition capacities appeared to influence DMC.