Decision-making in normal and pathological aging

Abstract

Decision making is a complex ability that is likely to be damaged in numerous psychiatric and neurologic disorders and also during the aging process. It therefore implies a large interconnection of cortical and subcortical structures that are directly impacted by the neuroanatomical and neurochemical modifications that occur during the usual or the pathologic aging. Two decision modalities have been isolated, depending on whether the decision making is performed under explicit knowledge of the risks taken or not. In the first case, the decision is taken based on success probabilities and also as a result of preliminary reinforcements (decision under risk). This modality is linked to the executive functions and its neural substrate would be the cognitive frontal striatal loops. In the second case, the decision is exclusively based on preliminary reinforcements (decision under ambiguity) and would be partially independent of cognitive functions. Its neural substrate would be the limbic frontal striatal loops. Nevertheless, the comparison of these hypothesis with the clinical data raises a certain number of controversies. Only the decision making under ambiguity appears to be responsive to the effects of usual aging, suggesting there would be a premature aging of the limbic loops. In Parkinson's disease, controversies appear to know whether the primitive decision impairment concerns the modality under risk or the one under ambiguity, as well as the question of the frontal striatal loops primitively damaged in this pathology pending. Furthermore, the cortical neurodegenerative diseases seem to demonstrate that the decision under ambiguity may be impacted by the cognitive functions, challenging the assumed independency between these two processes. On basis of some studies, the authors suggest to reconsider the links between the decision making, in particular the under ambiguity one and the cognitive functions, questioning how executive functions contribute to this decision modality.