Abstract
Taking relevant decisions (in his interest or that of his relatives) is necessary for our adaptation, our autonomy and our survival. However, decision-making is a complex and composite ability, which is particularly sensitive to the effects of aging. Two decision-making conditions are usually distinguished: decision under ambiguity in which the probability of the result is ignored and decision under risk in which the consequences and the probabilities of these consequences are known. This review outlines the major age-related changes in decision-making processes. In normal aging, impaired decision-making is mainly related to executive function decline. In normal aging, decision under risk seems to be better preserved than decision under ambiguity. During pathological aging, the location of the cerebral lesions plays an important role on the type of decision-making problems encountered. Thus, frontal and/or sub-cortical frontal lesions lead to greater risk-taking, especially in ambiguous conditions. In this condition, reinforcements have a prevalent role. Frontal and/or sub-cortical frontallesions make theses reinforcements particularly inefficient, hindering the ability to anticipate the probability of the outcome. Impaired decision making under risk is related to executive dysfunctions and damage of the expected reward system. The patients become unable to recognize and anticipate the consequences and their probabilities on the outcome. Temporal or temporofrontal lesions affect decision-making under ambiguity anddecision making under risk. Impairment of risky decisions is due to the inability to accurately estimate the probabilities of the consequences. Decision-making disorders under ambiguity are linked with difficulties to learn by “feedback” and to anticipate the likelihood of the outcome. These results highlight the complexity and variety of mechanisms and processes of decision-making activities. These data also help to explain the dissociation observed, depending on the type of brain damage identified in the context of normal and pathological aging.