The neuropsychology of prospective memory in normal aging: a componential approach.

To guide understanding of the neuropsychology of prospective memory and aging, we highlight several components of prospective memory, including planning an intended action, retrieving the action at the appropriate moment, and executing the action. We posit that frontal systems are particularly important for prospective memory tasks that require planning, that require strategic monitoring to detect the appropriate moment for executing the prospective memory intention, or for which execution of the retrieved intention must be delayed briefly. Drawing from a variety of approaches, including neuroimaging (with young adults) and studies examining individual differences relating to frontal functioning, we assemble preliminary evidence that supports this hypothesis. Further, because aging especially disrupts frontal functioning, the above noted prospective memory tasks would thus be expected to display the greatest age-related decline. The available literature confirms this expectation. A second key hypothesis is that some prospective memory tasks--those requiring minimal planning and supporting spontaneous retrieval--do not rely extensively on frontal processes but instead rely on medial-temporal structures for reflexive retrieval. These prospective memory tasks tend to show minimal or no age-related decline. The literature, though sparse with regard to the neuropsychological underpinnings of this kind of prospective memory task, is consistent with the present hypothesis.