Differential effects of negative and positive emotional content over veridical and false recognition in aging and Alzheimer's disease

Alzheimer's disease (AD) patients are known to present semantic memory impairments, and semantic processing plays a crucial role in the formation of false memories. We assessed 40 early stage AD patients and 35 matched healthy volunteers with an emotional version of the Deese-Roediger-McDermott paradigm, which allows the study of false memory formation. Participants were presented with three negative, three neutral and three positive lists of words, each semantically associated to a critical unpresented word. After the presentation of the lists the volunteers were asked to respond to a recognition questionnaire stating whether these critical lures, as well as other presented and unpresented words, had been previously shown or not. We replicate the pattern of decreased discriminability between list-related and -unrelated items for AD patients compared to healthy seniors observed in previous studies. Moreover, like control participants, AD patients displayed enhanced true recognition for emotional materials, both positive and negative. With regards to false recognition, our data show decreased discriminability between related and unrelated lures for positive material. These results point out differential involvement of semantic-based information during memory formation in AD patients compared to healthy seniors. Nevertheless, our data indicate that emotional content effects over semantic-based false memory formation persist in this population, at least at early stages of disease development