Moral Emotions and Their Brain Structural Correlates Across Neurodegenerative Disorders

Abstract

Background: Although social cognition is compromised in patients with neurodegenerative disorders such as behavioral variant frontotemporal dementia (bvFTD) and Alzheimer's disease (AD), research on moral emotions and their neural correlates in these populations is scarce. No previous study has explored the utility of moral emotions, compared to and in combination with classical general cognitive state tools, to discriminate bvFTD from AD patients.

Objective: To examine self-conscious (guilt and embarrassment) and other-oriented (pity and indignation) moral emotions, their subjective experience, and their structural brain underpinnings in bvFTD (n = 31) and AD (n = 30) patients, compared to healthy controls (n = 37). We also explored the potential utility of moral emotions measures to discriminate bvFTD from AD.

Methods: We used a modified version of the Moral Sentiment Task measuring the participants' accuracy scores and their emotional subjective experiences.

Results: bvFTD patients exhibited greater impairments in self-conscious and other-oriented moral emotions as compared with AD patients and healthy controls. Moral emotions combined with general cognitive state tools emerged as useful measures to discriminate bvFTD from AD patients. In bvFTD patients, lower moral emotions scores were associated with lower gray matter volumes in caudate nucleus and inferior and middle temporal gyri. In AD, these scores were associated with lower gray matter volumes in superior and middle frontal gyri, middle temporal gyrus, inferior parietal lobule and supramarginal gyrus.

Conclusion: These findings contribute to a better understanding of moral emotion deficits across neurodegenerative disorders, highlighting the potential benefits of integrating this domain into the clinical assessment.

Keywords: Alzheimer’s disease; behavioral variant frontotemporal dementia; moral emotions; neural correlates; social cognition.

Fig. 1.

Example of the Moral Sentiment Task stimuli. A) Participants read a scenario describing a social situation. After reading each scenario, the participants were asked to select, from a forced-choice list, the emotional category they would feel in that situation (accuracy). B) Additionally, we assessed the participants’ emotional experience. The subjects rated the emotional intensity and emotional concern using 10-points visual analog Likert scales.

Fig. 2.

Group comparisons on the Moral Sentiment Task. A) Comparisons of basic emotions; B) Comparisons of moral emotions. Comparisons between groups were performed through one-way ANOVA.

Fig. 3.

Brain regions related to moral emotions accuracy scores. A) Brain regions associated with lower moral emotions accuracy scores in bvFTD patients; B) Brain regions associated with lower indignation accuracy scores in bvFTD patients; and C) Brain regions associated with lower indignation accuracy scores in AD patients (p > 0.001, uncorrected, extent threshold = 30 voxels).