Ambiguous idiom comprehension in Alzheimer's disease.

Ambiguous idiom comprehension was examined in 15 patients with mild probable Alzheimer's disease (AD) by means of two tasks: a string-to-picture matching task and a string-to-word matching task. In the first, patients had to choose among four pictures, while in the second they chose among four words. For both tasks the alternatives were the picture/word corresponding to the figurative meaning, a semantic associate (picture/word) to the last word of the idiom, and two unrelated alternatives, which were, in the case of words, an unrelated foil preserving the semantic class and a literal continuation foil (a word that can follow the verb in that sentence), while in the case of pictures the first was substituted by an unrealistic foil. The patients were also submitted to three language, one visuo-perceptual, and two executive tasks. Idiom comprehension was poor, particularly when the string-to-picture matching task was used, and correlated with executive tests. We confirm that linguistic and extralinguistic factors must be taken into account to explain ambiguous idiom interpretation, and we underline the role of the testing modality in the case of pathological populations.