AbstractBackgroundHippocampal volume atrophy is one of the most acknowledged supportive biomarkers for Alzheimer´s disease (AD). However, how hippocampal volumes along the anterior‐posterior axis mediate memory in aging and dementia is still subject of ongoing research. This study aimed to investigate the difference in volume of the hippocampus and its anterior and posterior subregions in a healthy young and senior control group as well as in mild cognitive impairment (MCI) due to AD and its ability to predict performance in spatial memory tasks.MethodThirteen healthy young controls (24.9 ± 2.8 years), fourteen healthy senior controls (66.6 ± 8.2 years) as well as fifteen MCI patients (71.1 ± 6.0 years) with biomarkers typical for AD were included in this study. Subject‐specific manual tracing of hippocampi according to the EADC‐ADNI Harmonized Protocol for Hippocampal Segmentation (HarP) was performed on high‐resolution T1‐weighted MRI. Following the segmentation into anterior and posterior hippocampal parts, volumetry of anterior, posterior and total hippocampus was computed. Every subject performed a combined spatial memory and object recognition paradigm. Brain‐behavior correlations were conducted in order to explore prediction of spatial memory performance.ResultVolume measures of the hippocampi significantly differentiated healthy from pathological aging. Larger volume of posterior hippocampus in MCI patients correlated with higher performance scores in the spatial memory task (mean percentage of successfully retrieved object locations) whereas total and anterior hippocampal volume did not predict performance in the spatial memory task.ConclusionThese results support a functional hippocampal anterior‐posterior differentiation in memory processes and further stress the importance of integrating the dissociation of the hippocampus along its long‐axis concerning functional connectivity in memory processes and dementia.