Comprehension of metaphors and idioms in patients with Alzheimer's disease: a longitudinal study.

Language in patients with Alzheimer's disease has been extensively studied, with the exception of non-literal language comprehension. However, in our speech, we often make use of expressions, which are not necessarily interpreted on a literal ground. Comprehension of metaphors and idioms was examined in 39 patients with probable early Alzheimer's disease. The results showed that the decline of figurative language is not an early symptom of dementia and can occur independently from the impairment of propositional language. It was also found that metaphors and idioms differ as far as the predominant kind of error is concerned.