Learning deficits in late middle‐aged <i>APOE</i> ε4 carriers: Implications for emergent Alzheimer’s disease

In late middle-aged adults, ε4 was associated with a large reduction in ability to learn novel information. This impairment was not evident in performance on conventional cognitive tests. It is likely that Aβ levels in this group are increasing abnormally or have reached threshold for abnormality. Placed in the context of our previous observations, these data support the hypothesis that the earliest cognitive abnormality to reflect AD pathophysiological processes is a reduced ability to benefit from new information.