Impact of Age on Cognitive Testing Practice Effects and Cardiorespiratory Responses

Figures

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  Figure 1.. Four individual trials of 9-word immediate free-recall (A) and the sum of the 4 trial scores (B) during the first and second visits in young and older adults with healthy cognition. Panel A: 9-word immediate free-recall (circles: first session; triangles: second session) in younger (open symbols) and older (filled symbols) adults. Three-factor ANOVA: Immediate free recall scores are greater in the younger than older subjects (age factor p < .001) and increased when the trials were repeated (trial factor p < .001) during the second visit (retest factor p < .001). Post-hoc analysis shows that from trial 2 onward, all immediate free-recall performance scores were significantly increased (p < .05) versus the respective trial 1 scores in both groups during both visits. Panel B: The sum of 4-trial immediate free-recall performance was significantly affected by both the age and retest factors of two-factor ANOVA, indicating an age-related difference in verbal learning ability and practice effect on test-retest performance in the four trials of free-recalls during CVLT-II. p values are from post-hoc analysis.

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  Figure 2.. Heart rate (A) and breathing frequency (B) at rest and during mini-mental state examination, trail-making test and digit-span test. Panel A: Three-factor ANOVA revealed increased heart rate during cognitive testing-related mental stress (stress factor p = .003) in the younger but not older adults (age factor p < .001) and decreased stress effect during the second visit (retest factor p < .001). Panel B: Breathing frequency increased during cognitive testing (mental stress factor p = .005), but this effect diminished during the second visit (retest factor p < .001). The breathing frequency responses to the cognitive challenges were similar in the two groups (age factor p = .650). *p < .05 between the age groups within the same visit or cognitive test; †p < .05 versus the resting value of the same visit and age group; ‡p < .05 versus the first visit score for the same age group.

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  Figure 3.. Relationships of cognitive test scores versus heart rate (A–C) and breathing frequency (D–F) during test-retest of mini-mental state examination (MMSE), trail-making test (TMT-B) and digit-span test (DST). Panels A–C: heart rate was significantly higher in the younger than older subjects during the first testing session in different cognitive domains. Furthermore, the differences in heart rate between the first and second sessions (retest practice effect) was attenuated in the older adults. Panels D–F: there were no age-related differences in breathing frequency during the three tests. The retest factor on breathing frequency was present. However, the cognitive retest effect on breathing frequency was attenuated in the older subjects, except during MMSE. *p < .05 between the age groups during the same visit; ‡p < 0.05 versus the first visit of that age group.