Semantic memory network resilience in aging: The role of abstract and semantically diverse words

Individuals continuously acquire new words and concepts throughout their lifespan. Previous research on semantic memory networks found that with increased age, semantic memory becomes less efficient, less organized, and more sparsely connected. Most of this work focused on concrete concepts, though abstract concepts comprise a significant portion of our knowledge and may fundamentally differ in their organization and lexical properties. The current study examined age-related differences in semantic networks of 47 younger adults (20-35 years) and 49 older adults (60-78 years) based on semantic relatedness judgments of words that varied in concreteness and semantic diversity. Adding abstract words to semantic memory estimations significantly altered the network structures and, in some cases, minimized age differences. Networks that included abstract words were more interconnected (higher clustering coefficients and lower modularity) and more efficient (shorter path lengths), and abstract words remained connected in the networks longer under simulated 'attacks' compared to concrete word networks. Independent effects of semantic diversity and concreteness suggest that words that are more semantically diverse or abstract are more connected in the networks. Finally, age-related differences were minimal when considering individual-based semantic memory networks that included both abstract and concrete words, while group-based network analyses suggested more prominent age differences consistent with previous observations (e.g., less efficiency, interconnectedness, and more segregation). Overall, this study advances our understanding of age-related differences in semantic memory highlighting the important influence that abstract words and semantic diversity have on the mental lexicon, and the importance of analyzing semantic networks with multiple approaches.