Clinical Manifestations.

Background: Despite the prevalent belief that socioemotional processing remains mostly intact in the early stages of Alzheimer's disease (AD), impaired Theory of Mind - the ability to understand and interpret others' thoughts, beliefs, and feelings - has been observed in persons with AD. During everyday conversations, the high cognitive loading of socioemotional interactions may adversely impact the ability of persons with AD to identify emotions and read others' intentions. This study aimed to investigate socioemotional perception capabilities in early-stage AD and to determine whether cerebellar and cerebral integrity predicts performance on socioemotional perception tests.

Semantic knowledge of social interactions is mediated by the hedonic evaluation system in the brain.

Attaching semantic meaning to sensory information received from both inside and outside our bodies is a fundamental function of the human brain. The theory of Controlled Semantic Cognition (CSC) proposes that the formation of semantic knowledge relies on connections between spatially distributed modality-specific spoke-nodes, and a modality-general hub in the anterior temporal lobes (ATLs). This theory can also be applied to social semantic knowledge, though certain domain-specific spoke-nodes may make a disproportionate contribution to the understanding of social concepts.

Salience driven attention is pivotal to understanding others' intentions.

Interpreting others' beliefs, desires and intentions is known as "theory of mind" (ToM), and is often evaluated using simplified measurement tools, which may not correctly reflect the brain circuits that are required for real-life ToM functioning. We aimed to identify the brain structures necessary to correctly infer intentions from realistic scenarios by administering The Awareness of Social Inference Test, Enriched subtest to 47 patients with behavioural variant frontotemporal dementia, 24 patients with progressive supranuclear palsy syndrome, 31 patients with Alzheimer's syndrome, and 77 older healthy controls. Neuroimaging data was analyzed using voxel based morphometry, and participants' understanding of intentions was correlated with voxel-wise and region-of interest data.