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Semantic cognition and executive control functions differentially predict propositional language production in younger and older healthy adults: a preliminary investigation
Poster Session D, Saturday, October 26, 10:30 am - 12:00 pm, Great Hall 3 and 4
Melody M.Y. Chan1, Jessica Chow2, Gail A. Robinson1,2; 1Queensland Brain Institute, University of Queensland, 2School of Psychology, University of Queensland
Propositional language production is an important cognitive capacity supporting social communication. It declines when people undergo normal ageing, but some older adults maintain this capacity in later life. Previous studies suggest that propositional language production is supported by both domain-specific (i.e., core language skills) and domain-general (i.e., semantic cognition and executive control functions) cognitive components. Yet, how these components interact and modulate this capacity in younger and older healthy individuals remains elusive. We sampled 30 younger adults (mean age = 19.53 years, s.d. = 2.93 years, male-to-female ratio = 8:22) and 27 older adults (mean age = 67.85 years, s.d. = 6.78 years, male-to-female ratio = 9:18). The groups were matched by sex ratio (p = .58) and fluid intelligence (Raven’s Progressive Matrices; p = .10). All participants performed cognitive tasks tapping propositional language production (i.e., describe a beach scene in 1 minute), reading [National Adult Reading Test (NART)], semantic representation [Graded Naming Test (GNT)], and executive/semantic control functions [i.e., semantic verbal fluency (1-minute, category: animal) – energization and semantic control; colour-word Stroop – inhibitory control]. Although the younger and older groups had comparable propositional language production performance (speech rate: younger = 128.79 words/min, s.d. = 23.41 words/min; older = 124.89 words/min, s.d. = 28.71 words/min; p = .58), they had different cognitive task performance profiles. The older group performed better in the picture naming task (GNT accuracy rate: younger = 57.56%, s.d. = 12.47%; older = 75.77%, s.d. = 13.42%; p < .001) and word reading task (NART IQ: younger = 112.50, s.d. = 3.69; older = 116.13, s.d. = 3.20; p<.001). However, they performed worse in the inhibitory control task (Stroop task completion time: younger = 17.62s, s.d. = 6.27s; older = 30.19s, s.d. = 17.63s; p < .001) and semantic verbal fluency task (total unique responses generated: younger = 27.47 words/min, s.d. = 5.37 words/min; older = 24.26 words/min, s.d. = 6.07 words/min; p = .039). Subgroup correlation and multiple linear regression analyses revealed that, semantic representation and executive control functions (but not reading) played differential roles in modulating propositional language production in younger and older adults. Better picture naming performance was only weakly associated with (r(29) = .37, p =.042), and significantly predicted [b = .70, BCa 95%CI (-.106, 1.22); p = .042], propositional language production in younger, but not older adults. Meanwhile, better fluency (r(26) = .60, p <.001) and inhibitory control (r(26) = .54, p =.001) performance was strongly associated with, and significant predicted [fluency: b = 2.19, BCa 95%CI (.66, 3.73); Stroop: b = .61, BCa 95%CI (.084, 1.14); p < .001], propositional language production in older, but not younger adults. To maintain propositional language production performance in older age, a greater knowledge reserve compensating for the decline in executive control functions is needed. Better energization and inhibitory control abilities underlie better propositional language production in older adults, which explains why some of the older adults are able to maintain this capacity in later life.
Topic Areas: Language Production, Control, Selection, and Executive Processes