Age-Related Differences in Motor Imagery: Working Memory as a Mediator

Abstract

Background/Study Context: Although motor imagery is a well-established phenomenon in healthy younger adults, it seems necessary to determine if older adults are still able to accurately perform imagery tasks before investigating the application of motor imagery in rehabilitation. Therefore, the purpose of this study was to determine if there is a progressive decline in motor imagery performance with age. Furthermore, we wanted to verify whether the effects of age on motor imagery were due to (or mediated by) deficits of working memory.

Methods: This study examined the key characteristics of the motor imagery ability in three groups of healthy older men and women (60–69, 70–79, and ≥80 years; mean age M = 73.8, SD = 8.3) and 40 younger subjects aged 20 to 30 years (M = 28.87, SD = 2.5). Imagery ability was measured using the Movement Imagery Questionnaire (MIQ), the Controllability of Motor Imagery (CMI) test, and two different chronometry tests. To estimate the mediational effect of working memory on age differences in the imagery measures, we employed latent variable structural equation modeling (SEM).

Results: The main findings indicated that motor imagery ability (generation, visual and kinesthetic imagery ability, controllability, and temporal organization) were better in young adults compared with older adults 70 years and older, but not in older adults 60 to 69 years of age. The analysis of the mediational effect of working memory on age differences in the motor imagery measures showed that the inclusion of working memory increased the amount of explained variance in the MIQ (ΔR ² = .03), in the CMI test (ΔR ² = .15), as well as in the mental chronometry tests (ΔR ² = .16)

Conclusion: Our findings suggest that there is potential for motor imagery to be compromised in the older age ranges, which may limit motor imagery as a rehabilitative strategy in older and in cognitively impaired individuals.

Notes

¹An approach to assessing the timing of mental processing is offered by the mental chronometry paradigm, which refers to the time course of information processing by the nervous system (Posner, 1978).

Note. Table shows mean values, with standard deviations given in parentheses (^T p < .10; ***p < .001).

²An examination of the intrasubject temporal variability of the test distances resulted in non significant effects for time and age group. Therefore, we decided to perform only one trial per condition to avoid fatigue.

Note. BTT = Block-Tapping Test; DS f = Digit Span forward; DS b = Digit Span backward; MIQv = Movement Imagery Questionnaire visual; MIQk = Movement Imagery Questionnaire kinesthetic; CMIrec = Controllability of Motor Imagery recognition; CMIreg10 = Controllability of Motor Imagery regeneration 10; CMIreg_t = Controllability of Motor Imagery regeneration total; abs_distance = absolute error for mental chronometry walking taks; absTUG = absolute error for Timed-Up-and-Go Test.

Note. AGFI = goodness-of-fit index adjusted for degrees of freedom; NFI = normed fit index; CM/df =minimum discrepancy divided by the degrees of freedom; RMSEA = root mean square error of approximation.