Comprehension of psychological predicates in Alzheimer's disease

Patients with Alzheimer's disease (AD) show a deficit in processing sentences with psychological verbs. Evidence from English suggests that their comprehension of object Experiencers is more impaired relative to subject Experiencers. Since Spanish is structurally different from English, in the present study we wanted to determine whether Spanish-speaking AD patients would show a different comprehension pattern. We tested comprehension of semantically irreversible sentences involving psych verbs with subject Experiencers, and accusative- and dative-marked object Experiencers in 10 native speakers of Spanish diagnosed with mild to moderate AD. We also tested their comprehension of semantically reversible sentences involving dative object Experiencers in two word orders (SVO, OVS). A paired-samples t-test revealed no statistically significant differences in their comprehension of subject vs. object Experiencers, or accusative vs. dative object Experiencers in semantically irreversible sentences, with one-sample t-test indicating comprehension above chance. However, their overall comprehension of psych verbs in semantically reversible sentences was poor, regardless of word order, and it was significantly worse than their comprehension of sentences with action verbs in the same word orders. Thus, our data indicate that the deficit in comprehension of psych verbs found in Spanish speakers with mild to moderate AD dementia differs from the pattern found in English, and that the deficit in AD patients' comprehension of psych verbs is more heterogeneous than previously thought.