Orbitofrontal and limbic signatures of empathic concern and intentional harm in the behavioral variant frontotemporal dementia

Perceiving and evaluating intentional harms in an interpersonal context engages both cognitive and emotional domains. This process involves inference of intentions, moral judgment, and, crucially, empathy towards others' suffering. This latter skill is notably impaired in behavioral variant frontotemporal dementia (bvFTD). However, the relationship between regional brain atrophy in bvFTD and deficits in the above-mentioned abilities is not well understood. The present study investigated how gray matter (GM) atrophy in bvFTD patients correlates with the perception and evaluation of harmful actions (attribution of intentionality, evaluation of harmful behavior, empathic concern, and moral judgment). First, we compared the behavioral performance of 26 bvFTD patients and 23 healthy controls on an experimental task (ET) indexing intentionality, empathy, and moral cognition during evaluation of harmful actions. Second, we compared GM volume in patients and controls using voxel-based morphometry (VBM). Third, we examined brain regions where atrophy might be associated with specific impairments in the patient group. Finally, we explored whether the patients' deficits in intentionality comprehension and empathic concern could be partially explained by regional GM atrophy or impairments in other relevant factors, such as executive functions (EFs). In bvFTD patients, atrophy of limbic structures (amygdala and anterior paracingulate cortex - APC) was related to impairments in intentionality comprehension, while atrophy of the orbitofrontal cortex (OFC) was associated with empathic concern deficits. Intentionality comprehension impairments were predicted by EFs and orbitofrontal atrophy predicted deficits in empathic concern. Thus, although the perception and evaluation of harmful actions are variously compromised in bvFTD, deficits in empathic concern may be central to this syndrome as they are associated with one of the earliest atrophied region. More generally, our results shed light on social cognition deficits in bvFTD and may have important clinical implications.