The aging population and those with amnestic mild cognitive impairment (aMCI) are at increased risk for developing Alzheimer’s disease (AD). Individuals with aMCI in particular may display pathological changes in brain function that ultimately result in a diagnosis of AD. In this review, we focus specifically on hippocampal hyperexcitability, a pathology sometimes detectable years before diagnosis, which has been observed in individuals with aMCI. We describe how changes in hippocampal activity are associated with, or in some cases may be permissive for, the development of AD. Finally, we describe how lifestyle changes, including exercise and dietary changes, can attenuate cognitive decline and hippocampal hyperexcitability, potentially reducing the risk of developing AD.