Cognitive and affective Theory of Mind in neurodegenerative diseases: neuropsychological, neuroanatomical and neurochemical levels

The paper reviews of all of the current evidence on Theory of Mind (ToM) abilities in patients with neurodegenerative diseases. ToM refers to the abilities to attribute mental states to others. Two neural systems are involved in processing other people's beliefs and intentions (cognitive component) and others' emotions and feelings (affective component). We hypothesize that patients with different neurodegenerative diseases may present different patterns of ToM deficits on the basis of how different neuropathological processes affect the neural bases of ToM components during the progression of a disease. The studies we reviewed provided evidence of a deficit of the cognitive ToM component in cortical (Alzheimer's disease and frontotemporal dementia) and frontal-subcortical (amyotrophic lateral sclerosis and basal ganglia disorders) neurodegenerative diseases. As regards the affective ToM component, it resulted markedly impaired in frontotemporal dementia; it also resulted that performances in tasks assessing this process are heterogeneous in Parkinson's disease and amyotrophic lateral sclerosis. The findings presented support the opportunity to introduce validated ToM tasks in the neuropsychological assessment of neurodegenerative diseases.