Hippocampal dysfunction in amnestic-type mild cognitive impairment: implications for predicting Alzheimer’s risk

Abstract

Functional MRI is an attractive method for studying cognitive task-related and resting-state patterns of brain activation and connectivity. Since hippocampal dysfunction has been widely reported in patients with amnestic-type mild cognitive impairment (MCI) with Alzheimer’s risk, a number of studies have focused on this region of the brain; these studies are reviewed here. Three principle findings are highlighted: first, impaired hippocampal function relates to disturbances in episodic memory encoding and retrieval in MCI, but possibly in different ways; second, there is evidence of a nonlinear relationship between memory function and hippocampal activity as one progresses through the stages of MCI to Alzheimer’s disease; and third, hippocampal function is intimately related to default mode network mechanisms. Future work should be directed toward extending our understanding of the relationships between hippocampal function in MCI and pathological and cognitive disturbance. This may be a valuable neuroimaging marker in the objective of early detection of the disease processes that presage the development of Alzheimer’s disease.