Behavioral variant frontotemporal dementia (bvFTD) is predominantly a disorder of socioemotional behavior (
1). This neurodegenerative disease involves frontal and anterior temporal lobes resulting in disturbances in social interactions and emotional blunting (
2). Investigators have characterized patients with bvFTD as being particularly impaired in self-conscious emotions, which are necessary for the type of feedback that promotes social behavior (
3,
4). These include social emotions such as shame, guilt, pride, and, most prominently, the ability to experience embarrassment.
bvFTD prominently impairs embarrassment and other self-conscious emotions (
7). Patients with bvFTD have decreased emotional reactivity to embarrassing stimuli, such as watching themselves singing (
1), decreased self-consciousness (
4), and impaired self-awareness from others’ perspective or self-referential processing (
3,
4,
8–
12). Despite reactivity to simple happy and sad emotional films and facial emotional responses to auditory startle (
4,
13), patients in early stages of bvFTD display fewer facial signs of embarrassment than control subjects (
4). Finally, bvFTD patients do not show embarrassment and corresponding autonomic reactivity when recognizing their own errors or mistakes (
14).
A decreased ability to experience embarrassment may be one of the most basic and early features of bvFTD. Patients with bvFTD are known to have emotional blunting, decreased empathy, and impaired self-referential emotions (
3,
4,
7,
13,
15). They exhibit impairment in experiencing embarrassment on an emotional level, although they are able to report embarrassment on a cognitive level (i.e., on the basis of what they believe should be felt) (
16). These patients also lack general emotional awareness, often react inappropriately to social norms, and experience difficulties in taking the perspective of others or in mentalization (“theory of mind”) (
17–
19). All of these deficits may further impair self-awareness of embarrassment. Consequently, an assessment of self-reports of embarrassment in social situations may be a highly sensitive measure for detecting early bvFTD, a disorder for which a definitive clinical test is lacking.
Discussion
Decreased ability to be embarrassed may underlie many of the social behavioral disturbances among patients with bvFTD, and an assessment of their awareness of embarrassment could aid in early recognition of this disorder. We investigated self-reports of embarrassment among patients with bvFTD compared with HCs. Patients did not differ from HCs on the total Embarrassability Scale score or on embarrassing items involving themselves; however, compared with HCs, patients reported experiencing significantly greater embarrassment for items involving embarrassing situations for others (vicarious). In comparison, caregivers rated bvFTD patients as having social dysfunction and emotional blunting, and the patients rated themselves worse than HCs in responding to social norms. Finally, results from the Embarrassment Scale correlated with overadherence to social norms. Together, these findings suggest that among patients with bvFTD, increased endorsement of vicarious embarrassment may reflect an inability to take another’s perspective, resulting in rule-based responses regarding levels of embarrassment.
Social emotions, such as embarrassment, are distinct from basic emotions (
5); in particular, they require the ability to view oneself and others from the perspective of others (
29–
31). Self-embarrassment involves self-appraisal of adherence to social norms as seen by others, prompting corrective or reparative actions when necessary (
5,
32–
42). However, embarrassment can also be a vicarious experience when perceiving the embarrassing actions or mistakes of others (
6,
43). In observing someone else violating social norms with potential for social disapproval (
44), people imagine themselves from the other’s perspective. Vicarious embarrassment, or fremdscham, is distinct from emotional contagion because it does not require observing the other person’s emotional reaction or even the presence of third parties (
43). Both forms of embarrassment rely on taking the perspective of others, an aspect of theory of mind, and assessing violations of social norm rules.
Self-conscious emotions, such as embarrassment, involve the frontal, temporal and limbic areas affected by bvFTD (
36,
41,
42,
45–
48). Frontopolar, ventromedial frontal, and basal forebrain regions are involved in prosocial sentiments such as embarrassment (
47). In an embarrassing task in which bvFTD patients watched themselves singing karaoke, there was decreased physiological and behavioral reactivity associated with smaller right pregenual anterior cingulate cortex gray matter volumes (
49). Situations that trigger vicarious embarrassment involve brain areas associated with pain (either physical or social), such as the anterior cingulate cortex and the left anterior insula (
43,
50). These are areas affected early in the course of bvFTD.
Given the lack of self-conscious emotions and actual feelings of embarrassment in bvFTD, it is noteworthy that these patients report more vicarious embarrassment than HCs. There appear to be several reasons for this. First, patients with bvFTD have deficits in mentalization or theory of mind, the basic yardstick for taking the perspective of others (
18). Hence, their perspective is from their own point of view. Second, the claim of increased embarrassment is associated with overadherence errors to social norms. Increased overadherence errors in bvFTD correlate with difficulty recognizing the changing context of a rule (
22), and bvFTD facilitates rule-based and utilitarian judgments on the basis of previously learned social rules (
51,
52). Consequently, even in reporting self-embarrassment, patients with bvFTD may be responding less to actual social discomfort and more to what they perceive as an expected level of embarrassment. They may be applying the same predetermined rule for the level of self-embarrassment per social norm violation to the reporting of embarrassment for others.
There are several alternative, but less plausible, explanations for the results in the present study. The patients with bvFTD could have had a truly increased sense of vicarious embarrassment. This interpretation, however, is inconsistent with the vast body of research on socioemotional impairments in bvFTD (
3,
4,
7,
13,
15), including the basic diagnostic criteria of loss of empathy or sympathy (
2). A second consideration is that for vicarious items, bvFTD patients reported the perceived embarrassment or social discomfort of others rather than their own. However, this seems very unlikely given the clear task instructions and vicarious reports, as well as the impaired mentalization and perspective taking among patients with bvFTD (
17–
19). Another consideration is that in this study, we could not entirely exclude an effect on the results from the limited, established reliability and other psychometric aspects of the Embarrassability Scale and other measures.
There are several limitations to this study that could be addressed in future investigations. First, there is the consideration of the small number of study subjects, especially in the bvFTD group. The number of participants was sufficient to disclose group differences on some scales but not on others. Second, it would have been beneficial to include a direct measure of mentalization or theory of mind. Third, it would also have been advantageous to have had autonomic measures for assessing a physiological reaction of embarrassment. Fourth, the modified Embarrassability Scale has not been broadly validated in a large population. Finally, other control groups, such as patients with Alzheimer’s disease, were not included.