The personal/impersonal distinction of moral decision-making postulates intuitive emotional responses from medial frontal activity and rational evaluation from lateral frontal activity. This model can be analyzed in behavioral variant frontotemporal dementia (bvFTD), a disorder characterized by impaired emotional intuitions, ventromedial prefrontal cortex involvement, and relative sparing of lateral frontal regions. Moral dilemmas were presented to 10 bvFTD, 11 Alzheimer’s disease (AD), and 9 healthy control (HC) participants while recording skin conductance responses, a measure of emotional arousal. We evaluated their personal vs. impersonal conflict, subjective discomfort, and adherence to social norms. Replicating prior work, bvFTD participants were more willing to harm in the personal, but not the impersonal, dilemma compared to AD and HC groups. BvFTD participants had lower arousal and less of an increase in conflict on the personal vs. the impersonal dilemma, in contrast to increased arousal and conflict for the AD and HC groups. Furthermore, bvFTD participants verbalized less discomfort, a correlate of low adherence to social norms. These findings support impaired emotional reactions to moral dilemmas in bvFTD and vmPFC lesions and the personal/impersonal model. It suggests a reversion to utilitarian-like considerations when emotional intuition is impaired in the brain.

Background The most characteristic manifestations of behavioral variant frontotemporal dementia (bvFTD) are abnormalities in social behavior. However, distinguishing bvFTD based on social behavior can be difficult in structured clinical settings. Methods Using a Social Observation Inventory, 10 patients with bvFTD and 10 patients with Alzheimer’s disease (AD) were compared to their caregiver interlocutors on 1-hour mealtime, in-home videotaped segments. Results Compared to caregivers and patients with AD, patients with bvFTD were significantly disturbed in social behavior. In contrast, patients with AD were indistinguishable from their caregivers. The lack of “you” comments and decreased tact and manners distinguished 92.6% of the patients with bvFTD from patients with AD and caregivers. The Social Observation Inventory scores correlated with scores on frontal-executive tests and socioemotional scales. Conclusions The systematic observation of social behavior during routine activities may be one of the best ways to distinguish patients with bvFTD from normal individuals and from patients with other dementias.

Behavioral changes in dementia, especially behavioral variant frontotemporal dementia (bvFTD), may result in alterations in moral reasoning. Investigators have not clarified whether these alterations reflect differential impairment of care-based vs. rule-based moral behavior. This study investigated 18 bvFTD patients, 22 early onset Alzheimer’s disease (eAD) patients, and 20 healthy age-matched controls on care-based and rule-based items from the Moral Behavioral Inventory and the Social Norms Questionnaire, neuropsychological measures, and magnetic resonance imaging (MRI) regions of interest. There were significant group differences with the bvFTD patients rating care-based morality transgressions less severely than the eAD group and rule-based moral behavioral transgressions more severely than controls. Across groups, higher care-based morality ratings correlated with phonemic fluency on neuropsychological tests, whereas higher rule-based morality ratings correlated with increased difficulty set-shifting and learning new rules to tasks. On neuroimaging, severe care-based reasoning correlated with cortical volume in right anterior temporal lobe, and rule-based reasoning correlated with decreased cortical volume in the right orbitofrontal cortex. Together, these findings suggest that frontotemporal disease decreases care-based morality and facilitates rule-based morality possibly from disturbed contextual abstraction and set-shifting. Future research can examine whether frontal lobe disorders and bvFTD result in a shift from empathic morality to the strong adherence to conventional rules.