Objective:Spatial navigation performance deficit is very common in Alzheimers disease patients,also,APOE is considered as a major risk gene for Alzheimers disease(AD),there are many studies between Spatial navigation and APOE in Alzheimers patients,and the spatial navigation performance and memory has relationship to hippocampus,In young adults,spatial memory has not been thoroughly assessed in relation to APOE in spite of its dependence on the hippocampus in domestic.We want to investigate the relationship between spatial navigation performances and hippocampal structural changes in young healthy APOE ε4 carriers.Methods:35 young healthy volunteers who come from Nanjing university and Nanjing medical university were recruited.All participants underwent the 2D spatial navigation test and high resolution MRI scans.Then,it is available to get their spatial navigation performances,and their hippocampal and hippocampal subfields volumes were easy to gained by Freesurfer software.Result:We found that the spatial navigation skills didnt has obvious correlation with hippocampal volume,but with its subfields volume(right fimbria and presubiculum)(P<0.05).However,as to the spatial navigation skills and hippocampal volume,there is no significant difference in different APOE types.Conclusion:The spatial navigation skills didnt has obvious correlation with hippocampal volume may because the young healthy people have no deficit in spatial navigation skills,there is no atrophy in the volume of hippocampus,so there is no obvious correlation between them.However,the presubiculum provides a major input to the medial entorhinal cortex(MEC)and contains cells that encode for the animals head direction(HD),as well as other cells likely to be important for navigation and memory,including grid cells.Also,presubiculum,part of a network involved in spatial navigation and memory,it can explain the correlation between the complex spatial navigation skills and the volume of the right presubiculum.Because in our study,the ε4 carriers is too few(only 7 in 35),it is possible that there is a bias in our data,that maybe the reason that there is no significant difference in different APOE types.In short,in young healthy volunteers,their spatial navigation skills have correlation with the volume of right hippocampal subfield--fimbria and presubiculum.