Aging affects the engagement of the hippocampus during autobiographical memory retrieval

Surprisingly little is known about the neural correlates of remembering real life events in the context of normal aging. We therefore asked young and older adults to retrieve real life autobiographical event memories accrued over decades, while their brains were scanned using functional MRI. There were many commonalities between the groups in the wider network of brain areas active during retrieval. Nevertheless, one key difference emerged; while left hippocampal activation was apparent in the young, bilateral hippocampal activation was evident in older adults and direct comparison between the groups confirmed significantly greater right hippocampal activation in older adults. Notably, this difference was specific to autobiographical event memory retrieval, as the groups were comparable in the areas active during semantic memory retrieval. The present findings show that even when stimuli, tasks and performance appear indistinguishable between young and older adults, neural changes occur in aging with specificity in both the memory type and the brain regions affected. In particular, the results reveal that age-related effects are detectable in the hippocampus. This highlights the need to consider how the dynamic course of normal aging interacts with pathological processes that might also affect the hippocampus. Understanding this relationship may aid prognosis, as well as providing insights into plasticity in the anatomy of memory.