Generation of novel semantic representations in aging and Alzheimer’s disease

The process of combining two words to create or identify a new concept is highly productive in English. A noun–noun compound may be interpreted by integrating a feature of the modifying noun into the head noun’s representation (property interpretation), or by aligning the referents in a context (relational interpretation). In the present study, young (n = 13) and older (n = 15) adults, and patients with probable Alzheimer’s disease (AD, n = 11) generated definitions for novel compounds. Older adults produced fewer property, but not relational, interpretations than younger adults, suggesting that the two routes to interpretation are dissociable. Young adults produced more expected and fewer unexpected property interpretations than older adults; higher production of unexpected property interpretations by AD participants relative to older adults was also observed. This finding may be due to impairments in inhibitory functioning in healthy aging and AD, which result in reduced inhibition of irrelevant or less salient features of the modifying noun. All participants produced both types of interpretation, suggesting that both comprehension routes are available in healthy aging and AD.