Longitudinal evidence for increased functional response in frontal cortex for older adults with hippocampal atrophy and memory decline
2017 (English)In: Cerebral Cortex, ISSN 1047-3211, E-ISSN 1460-2199Article in journal (Refereed) Epub ahead of print
The functional organization of the frontal cortex is dynamic. Age-related increases in frontal functional responses have been shown during various cognitive tasks, but the cross-sectional nature of most past studies makes it unclear whether these increases reflect reorganization or stable individual differences. Here, we followed 130 older individuals' cognitive trajectories over 20-25 years with repeated neuropsychological assessments every 5th year, and identified individuals with stable or declining episodic memory. Both groups displayed significant gray matter atrophy over 2 successive magnetic resonance imaging sessions 4 years apart, but the decline group also had a smaller volume of the right hippocampus. Only individuals with declining memory demonstrated increased prefrontal functional responses during memory encoding and retrieval over the 4-year interval. Regions with increased functional recruitment were located outside, or on the borders of core task-related networks, indicating an expansion of these over time. These longitudinal findings offer novel insight into the mechanisms behind age-associated memory loss, and are consistent with a theoretical model in which hippocampus atrophy, past a critical threshold, induces episodic-memory decline and altered prefrontal functional organization.
Place, publisher, year, edition, pages
aging, fMRI, hippocampus, longitudinal study, memory decline, prefrontal cortex
Neurosciences Psychology (excluding Applied Psychology)
IdentifiersURN: urn:nbn:se:umu:diva-131270DOI: 10.1093/cercor/bhw418PubMedID: 28119343OAI: oai:DiVA.org:umu-131270DiVA: diva2:1073359