Theory of mind and pragmatic abilities in dementia

"Theory of Mind" (ToM) is the capacity to attribute mental states to oneself and to others and to interpret behavior in terms of mental states. Deficits in both ToM and pragmatic abilities have been described in patients with neurologic disorders, such as frontal lobe lesions and right hemisphere strokes, but have not been assessed in demented patients.

This study examined ToM and pragmatic abilities in a consecutive series of 34 patients with probable Alzheimer disease (AD) using a second-order false belief story, 11 short stories assessing understanding of social situations, and a test of pragmatic abilities assessing both indirect requests and-conversational implications.

Sixty-five percent of AD patients with mild dementia could not pass a second-order false belief task, whereas no failures were found in a group of 10 age-comparable healthy controls. AD patients who did not pass the second-order false belief task had more severe deficits on tests of verbal anterograde memory, verbal comprehension, abstract thinking, and naming, as compared with AD patients who passed the task. AD patients also showed significantly more severe pragmatic deficits than age-comparable healthy controls, and there was a significant association between ToM and pragmatic deficits. On the other hand, there were no significant associations between ToM or pragmatic deficits, and behavioral problems frequently reported in AD such as depression, delusions, apathy, and irritability.

This initial exploratory investigation demonstrated significant deficits in both ToM and pragmatic abilities in a consecutive series of AD patients with mild dementia.