Pragmatic skills in the early stages of Alzheimer's disease: an analysis by means of a referential communication task.

Background: Disordered discourse in cases of senile dementia of Alzheimer's type (DAT) has mainly been described in conversation and picture description tasks. The referential communication task provides researchers and clinicians with new insights on the nature of these disorders.

Aims: To study to what extent persons suffering from DAT can benefit from shared experience through trial repetition to achieve common reference.

Methods & Procedures: Thirteen persons suffering from DAT at minimal or mild stage (MMSE score range = 18-27) were compared with 13 healthy elderly adults (64-86 years) in neuropsychological assessment of executive functions and in a referential communication paradigm. To study how the two partners achieve mutual understanding by progressively elaborating a common ground, the task was repeated three times.

Outcomes & Results: Persons with DAT produced a larger number of words than control participants and they benefited from the task repetition. However, they were less able to take into account previously shared information, used no definite referential expressions and were more idiosyncratic in their descriptions of the referent. This decline of communicative effectiveness was found not to relate closely to executive deficits.

Conclusions: Collaborative exchanges allow healthy elderly persons to ground reference in common experience. This process is severely disturbed in persons with DAT, in relation to poor memory of preceding episodes or to other cognitive impairments.