Beyond increasing age, the ε4 allele of the Apolipoprotein-E (APOE) gene represents the most important risk factor for Alzheimer's disease (AD) and spatial navigation deficits usually occur beyond memory dysfunction in the preclinical phase. New technological solutions, such as wearable devices represent promising means for assessment, monitoring and intervention in AD. The present study aims at comparing performances of 83 community-dwelling senior citizens, clustered into three groups, healthy controls (n. 33), individuals with subjective cognitive decline (SCD) (n. 25) and patients with Mild Cognitive Impairment (MCI) due to AD (n. 25) undergoing an open-space naturalistic task revealing topographical disorientation measured by wrong turns (WTs) and moments of hesitation (MsH). All the participants were also genotyped for ApoE-ε4 and worn the sensorial garment, i.e., The Howdy Senior System(®) by Comftech revealing real-time physiological and gait indexes thanks to an accelerometer. The protocol was registered on ClinicalTrials.gov. Non-parametrical stastistical analyses were performed. Patients with MCI due to AD carrying the APOE-e4 allele showed more WTs and MsH that individuals with SCD (p=0.003, p=0.007), and healthy controls (p=0.001, p=0.002), respectively, especially in allocentric navigation. Individuals carrying at least one APOE-e4 allele presented with gait alterations specifically pertaining Speed (p=0.027) and Direction (p= 0.015) than non-carriers across groups. We documented that building a cognitive map of the surrounding environment is difficult for APOE-e4 carriers and behavioral alternations of spatial cognition in MCI due to AD can be detected by sensorial garments prior to dementia.