Ecological assessment of emotional enhancement of memory in progressive nonfluent aphasia and Alzheimer's disease

Background: Events which are imbued with emotion are typically remembered vividly and with more confidence than similar non-emotional events. The extent that emotional enhancement of memory is compromised in neurodegenerative disorders is unclear, despite differential effects of dementia on emotion processing ability. Objective: To examine emotional enhancement of memory using an ecologically valid task in progressive nonfluent aphasia (PNFA), an expressive language subtype of frontotemporal dementia, in comparison to Alzheimer's disease (AD) and matched-controls. Methods: Twenty-five dementia patients (13 PNFA, 12 AD) and 10 controls viewed either an emotionally arousing or a closely matched non-emotional story. Multiple-choice recognition memory was tested after a 1-hour delay. The alternate story was presented two weeks later. Results: PNFA showed a similar level of memory for the emotional and neutral story, whereas both controls and AD remembered significantly more details from the emotional than the neutral story. Correlation analyses indicated that in PNFA, emotional story memory correlated with reduced emotion recognition, whereas in AD, neutral story memory correlated with visual recall memory performance only. Furthermore, in PNFA, reduced emotional memory enhancement was associated with increased carer stress and depression. Conclusion: Emotional memory enhancement is absent in PNFA, whereas emotion facilitates memory for real-life events in AD. Disrupted emotional memory enhancement in PNFA is associated with reduced emotion recognition ability, suggesting that widespread emotion processing dysfunction is present in this disease. Crucially, loss of emotional enhancement influences carer wellbeing, which represents an important avenue for future studies to examine.