Alzheimer’s disease affects the ability to bind information in memory. Memory binding impairments have been reported in asymptomatic and symptomatic carriers of a PSEN1 mutation which has 100% penetrance (i.e., E280A). E280A asymptomatic carriers showed visual short-term memory binding (VSTMB) deficits which anticipate deficits of associative memory functions such as that assessed by the Selective Reminding Test (SRT). E280A-PSEN1 is a rare genotype whose phenotype is unaffected by factors such as age. VSTMB and SRT have proved differentially sensitive to aging. We investigated the impact of a more common genotype, namely APOE4, on memory binding functions in older adults with different cognitive status. A group of 100 APOE4 carriers (APOE4+ = at least one e4 allele) and 137 non-carriers (APOE4-) were included in this the study. Twelve carriers and nine non-carriers met criteria for Mild Cognitive Impairment (MCI). Of the remaining 216 healthy older adults (HOA), 88 were APOE4+. They all underwent assessment with the VSTMB test and the SRT as part of a comprehensive neuropsychological protocol. We failed to find differences between APOE4+ and APOE4- in within-group contrasts. A mixed ANCOVA controlling for age, education, and depression showed a significant Group x Condition (Shape x Color x Binding) interaction. It was driven by a larger drop in performance of MCI-APOE4 + & - than HOA on the Binding than on the other two conditions (Figure 1). Whereas SRT performance was significantly poorer in both MCI groups than in HOA, VSTM binding reached significance only in MCI-APOE4+. Background data suggested that MCI-APOE4+ were in more advanced stages than MCI-APOE4-. After controlling for disease severity the results above remained unchanged. Interestingly, such findings also remain unchanged after controlling for ethnicity. The cognitive phenotype of HOA and MCI patients, as defined by traditional tests, was unaffected by the APOE4 genotype. As previously reported, MCI patients presented with VSTMB deficits. The SRT distinguished between MCI and HOA groups regardless of the APOE genotype. VSTMB impairments in MCI patients were associated to the APOE4 genotype in a way that was unaccounted for by disease severity and ethnicity. Mean data for the four groups of participants across the three conditions of the VSTMB test. The panel to the left shows performance measured as the proportion of correct recognition. The panel to the right shows the results of applying the signal detection theory.