Preserved recognition and selection of facial expression of happiness in mild Alzheimer’s Disease

Abstract

A decline in the ability to process facial expression of emotions has been reported in individuals with Alzheimer's disease (AD). However, the low number of participants and the lack of diversity in the tasks being used in previous studies leaves a gap in our knowledge about this issue. We recruited 169 participants including healthy older adults (HOA), participants with mild cognitive impairment (MCI) and AD patients at different stages of the disease (mild to moderate). Four tasks including recognition, selection, matching and declarative knowledge about facial expression of emotions were used. Face identification was used as a control task. Our results revealed that compared with HOA, MCI participants did not show any significant deficits in none of the tasks. AD patients did not show any impairment in the control task. However, they were impaired in the processing of facial expression of negative emotions across all four affective tasks. Interestingly, recognition and selection of happiness were intact in AD patients at the mild stage of the disease. Our findings suggest that despite the pathology affecting distributed areas in the brain, the less challenging aspects (recognition and selection) of the ability to process the facial expression of happiness were preserved at the early stage of the disease. By recruiting a large number of participants using several different tasks our study provides a comprehensive picture of the disorders of facial emotion processing in Alzheimer's Disease. Our findings have significant implications for improving the AD patients' quality of life and the quality of their social interaction with others. Future studies might start to investigate the processing of emotions in AD patients in other modalities rather than visual.

Impaired Recognition of Facial and Vocal Emotions in Mild Cognitive Impairment

“…The discrepancy in relation to previous findings might stem from differences in sample characteristics or from differences in methods. Expressions of happiness and disgust are often easier to recognize than those of fear and sadness and sometimes even associated with ceiling effects (e.g., McCade et al, 2011;Moradi, Najlerahim, & Humphreys;2018;Richard-Mornas et al, 2012;Spoletini et al, 2008;Weiss et al, 2008), and this could have masked group differences in previous work. Our stimuli were selected so that they would elicit intermediate levels of performance, and this might have made our tasks more sensitive to a wider range of impairments.…”