Processing emotional information in Alzheimer's disease: effects on memory performance and neurophysiological correlates

Background: There is some impairment of the ability of patients with Alzheimer’s disease (AD) to perceive emotions, but this ability seems relatively preserved compared to the impairment of other cognitive domains. Few studies have focused on the link between emotional processing and other cognitive functions, such as memory or attention. Objective: This study was designed to investigate whether the emotional content of a text can influence memory in patients affected by AD and whether this effect is related to attentional processes as measured by event-related potentials (ERP). Methods: All subjects were administered neuropsychological tests and a logical memory test including emotional and nonemotional material. ERP were recorded during an attention task. Results: AD patients had better immediate recall of sad and, to a lesser extent, happy stories than of neutral stories. This difference also affected multiple choice recognition and identification (immediate and delayed) of emotional content. The amplitude of both P300 and mismatch negativity was significantly decreased in the group as a whole. There was no correlation between P300 parameters and performance on the memory tasks, whatever their emotional content. Conclusions: The results show relatively preserved emotional processing in patients with AD and suggest that the emotional content of a context can influence memory performance. We found no evidence that this effect is mediated by attention as measured by ERP.