Enactment effect in patients with Alzheimer's disease

Introduction: Subjects can improve their performance on memory for action phrases if, during the encoding condition, they self-perform actions associated with verbs (subject-performed condition), or if they perceive the actions carried out by experimenter (experimenter-performed condition), with respect to a verbal task condition in which they only read or listen to the stimuli. This facilitation is labeled "Enactment effect" (EE), and is thought to be associated with episodic integration processes binding actions and nouns together in a coherent representation. Only recently, studies addressed EE in AD individuals reporting significant improvements on memory tasks in the subject-performed encoding condition. However, no studies tried to explore the cognitive mechanisms supporting EE in AD individuals. Method: Performance on recognition and cued recall tasks for action phrases were assessed in a sample of 32 mild-to-moderate AD individuals and 30 healthy adults, in verbal, subject-performed and experimenter-performed encoding conditions. Moreover, a cognitive assessment was completed to explore the possible correlates of EE in our participants. Results: Results showed that both subject-performed and experimenter-performed encoding conditions produced similar advantages over the verbal condition, in both memory tasks in both groups. Moreover, these memory advantages were strongly associated to executive processes, in both AD and healthy adults. Conclusions: The present study confirmed that EE is spared in mild to moderate AD. Our findings supported the role of episodic integration processes and suggested a contribution of executive processes in EE.