Emotional enhancement of memory in Alzheimer’s disease dementia: a systematic review

Abstract

Progressive decline in episodic memory is a hallmark of Alzheimer’s disease (AD). Emotional arousal is known to enhance memory. Enhanced encoding of emotionally arousing stimuli or events may improve memory in patients with AD; however, whether this effect is present in patients with AD remains unclear. Here we conducted a systematic search of the literature to identify relevant literature on emotional enhancement of memory in AD. Inclusion criteria were studies that (1) included individuals with Alzheimer’s disease and (2) assessed emotional memory, particularly episodic memory. Thirty-five studies were included. Twelve out of 35 studies (34.3%) showed clear emotional enhancement of memory for episodic memory among participants with mild AD, while 13 studies (37.1%) found no effect. Ten studies (28.6%) found that emotional enhancement of memory was influenced by stimuli type, valence of emotion, level of encoding or intensity of emotion. Studies including brain imaging showed that amygdala and hippocampus volume are strong predictors of emotional enhancement of memory in AD, regardless of level of cognitive impairment. Evaluating volumes or networks of brain regions known to be involved in emotional memory processing may be a key factor influencing the preservation of enhanced encoding of emotional information. Future studies are needed to confirm whether atrophy of memory-related brain regions diminishes emotional enhancement of memory in AD. Alzheimer’s disease (AD) is characterized by a decline in episodic memory, yet the potential for emotional arousal to enhance memory in patients with AD remains uncertain. Here the authors systematically review 35 studies, revealing that emotional enhancement of memory in AD is influenced by factors such as stimulus type and brain region volumes, suggesting potential therapeutic targets.