Measuring Sense of Agency in Neurodegenerative Dementias: Evidence From the Intentional Binding Effect

BACKGROUND: Apathy is a common neuropsychiatric syndrome in neurodegenerative dementias, though its underlying mechanisms are not well understood. It is characterized, in part, by a reduction in self-initiated action (ie, voluntary actions instigated by internal or external stimuli). The sense of agency (SoA) refers to the feeling of control over one's actions and the outcomes of those actions. Experimentally, SoA can be measured using the intentional binding effect, where the perceptual attraction of a voluntary action to an immediate effect of that action is indicative of increased SoA. OBJECTIVE: The current study aimed to investigate aberrant SoA as a potential mechanism contributing to apathy. METHOD: Thirty-eight participants with mild cognitive impairment or Alzheimer disease, frontotemporal dementia, Lewy body disease or Parkinson disease (LBD/PD), and healthy controls were recruited for this study. We used the total score on the Apathy Evaluation Scale to index apathy severity across participants. RESULTS: Our results did not show an association between apathy and intentional binding. However, there were significant group-based differences. Compared to healthy controls, participants in the LBD/PD group demonstrated significantly more intentional binding driven by a pronounced perceptual attraction of their actions to the subsequent outcomes. CONCLUSION: These findings suggest altered sensorimotor and cognitive control processes that may be associated with the self-initiation deficits seen in individuals with neurodegenerative dementias and apathy.