The recombined memory: associative inference in Alzheimer's disease.

Abstract

Associative inference refers to an adaptive ability that allows flexible recombination of information acquired during previous experiences to make new connections that they have not directly experienced. This cognitive ability has been widely associated with the hippocampus. We investigated associative inference in patients with Alzheimer's disease and control participants. The task has two phases. In the training phase, participants learned to encode overlapping pairs of objects (AB + BC). In the test phase, participants were invited to retrieve previously see associations (i.e., AB, BC) as well as novel associations between the previously exposed objects (i.e., AC). In addition, we test the relationship between associative inference and cognitive flexibility. Analysis demonstrated lower associative inference in AD patients than in control participants. Interestingly, performance on the associative inference task was significantly correlated with low performance on a cognitive flexibility task in AD patients. Our findings demonstrate a compromise of the ability to flexibly combine new representations from prior memories in AD, which is likely related to the hippocampal dysfunction in AD.