The Effects of Mixed Working Memory Training on Subsequent Training Gains Among Older Adults

Not Applicable

Completed

Conditions: Cognitive Aging

Interventions: Behavioral: Different Mixed Condition (DM)
Behavioral: Different Single Condition (DS)
Behavioral: Same Task (ST) Practice Control
Behavioral: Non-WM Placebo Control (PC)

Registration Number: NCT05672771

Lead Sponsor: University of Illinois at Urbana-Champaign

Brief Summary: While an intellectually active and socially integrated lifestyle shows promise for promoting cognitive resilience, the mechanisms underlying any such effects are not well understood. The aim of the current project is test the implications of the "mutualism" hypothesis, which suggests that intellectual function emerges out of the reciprocal influence of growth in abilities as they are exercised in the ecology of everyday life. Such a view implies that improvement in one component will enhance the modifiability of a related component. An additional aim was to test the idea that mutualistic effects will be enhanced by more diverse training in related skills, such as interleaved training of multiple skills, relative to single-component training.

A "successive-enrichment" paradigm was developed to test this with working memory (WM) as the target for training given its centrality in models of attention, intellectual function, and everyday capacities such as reasoning and language comprehension. All participants receive the same target training, but the nature of the training that precedes it is manipulated. Outcome measures include pre- to posttest gains in working memory and episodic memory, as well as the rate of gain in learning the target task. The principle of enhanced mutualism would predict that more diverse experiences related to the target skill will enhance efficiency in acquiring the target skill.

Detailed Description: Within conventional assessments of transfer that examine the effects of training on measures of function at a single time point, these ideas has not been tested. In this project, a "successive-enrichment" paradigm was used to examine improvement in cognitive skills as a function of different conditions for earlier training. The target for training is working memory (WM) given its centrality in models of attention, intellectual function, and everyday capacities such as reasoning and language comprehension.

In the successive-enrichment paradigm, all participants receive the same target training, but the nature of the training that precedes it is manipulated. Thus, in Phase 2, all participants are trained for 10 days on the reading span task (RdgS), in which the task is to verify sensibility in a set of sentences and retain in memory an alphabetic character presented after each sentence. The set size adapts to the participant's skill (in both accuracy of sensibility decisions and memory for the letter set). In Phase 1, participants are randomly assigned to one of four groups designed to test the assumption that related and diverse experiences with the target skill differentially enhance the rate of learning the new skill. In the Same Task (ST) control, participants train on the RdgS, and were expected to be at ceiling in Phase 2. In the Different Single condition (DS), participants trained on a WM task different from that in Phase 1 (the lexical decision span). In the Different Mixed (DM) condition, participants trained on two different interleaved WM tasks, the lexical decision span and the category span. In the non-WM Placebo Control (PC), participants train on a speeded lexical decision task (matched in materials and verbal decision component to the lexical decision span the but requiring no simultaneous memory.

Outcome measures include pre- to posttest gains in working memory and episodic memory, as well as the rate of gain in learning the RdgS in Phase 2. The PC and ST controls define the lower and upper limits of performance, respectively. The principle of enhanced mutualism would predict that the DM group will show more efficient learning of the RdgS in Phase 2 than the DS group, which will both show more efficient learning than the PC group.

Recruitment & Eligibility

Status: COMPLETED

Sex: All

Target Recruitment: 90

Inclusion Criteria

Native English speakers or acquisition of English before age 6 yrs old
Self-report of hearing ability sufficient to engage with lab personnel
No stroke in the last 3 years
No current cancer treatment involving radiation or chemotherapy - No self-reported learning disability
No self-reported psychiatric disorder
Willingness to be randomly assigned to training conditions
No plans that would limit participation during the activity period
No participation in a cognitive intervention program in the last year

No additional Exclusion Criteria.

Exclusion Criteria

Not provided

Study & Design

Study Type: INTERVENTIONAL

Study Design: FACTORIAL

Arm && Interventions

Group	Intervention	Description
Different Mixed Condition (DM)	Different Mixed Condition (DM)	Training in both Lexical Decision Span and Category Span in Phase 1 (which are both different from the target task Reading Span in Phase 2).
Different Single Condition (DS)	Different Single Condition (DS)	Training in the Lexical Decision Span in Phase 1 (which is different from the target task Reading Span in Phase 2).
Same Task (ST) Practice Control	Same Task (ST) Practice Control	Training in Reading Span task in Phase 1 (which is the same as target task in Phase 2).
Non-WM Placebo Control (PC)	Non-WM Placebo Control (PC)	Training in a speeded Lexical Decision task only (which has no memory component) in Phase 1 prior to Phase 2 training in WM.

Primary Outcome Measures

Name	Time	Method
Change in Reading Span	Change from Baseline to 5-6 weeks after pretest	Change in Reading Span score from pre- to posttest in z-score units ("standard unit change"). The change in z-score units was calculated \[(posttest score - pretest score) / standard deviation of the scores at pretest)\]. A z-score of 0 represents no change from pretest to posttest; the unit is the standard deviations of the sample at pretest (e.g., a score 0.5 would indicate a half standard deviation improvement in overall working memory). There is no agreed upon standard of clinical significance for improvement in working memory
Change in Overall Working Memory	Change from baseline to 5-6 wks after pretest	Average change in working memory from pre- to posttest in z-score units ("standard unit change"). For each working memory measure (Reading Span, Lexical Decision Span, Category Span, Operation Span, and Count Span), the change in z-score units was calculated \[(posttest score - pretest score) / standard deviation of the scores at pretest)\]. The score reported is the mean of these 5 values. A z-score of 0 represents no change from pretest to posttest; the unit is the standard deviations of the sample at pretest (e.g., a score 0.5 would indicate a half standard deviation improvement in overall working memory). There is no agreed upon standard of clinical significance for improvement in working memory

Secondary Outcome Measures

Name	Time	Method
Training Gains on the Reading Span Task in Phase 2	2 weeks	In Phase 2, training data on the target task (Reading Span) is collected over 10 days. Training gains are estimated by the coefficients for the condition contrast by training interaction in a linear mixed effects model, in which mean working memory score across training days was modeled as a function of the Phase 1 training condition. Using the lme4 and lmerTest packages for R version 4.2.2, a mixed-effects linear regression model was employed to model the mean daily span score with condition and training day as the fixed factors, and a by-subject random intercept, using the restricted maximum likelihood (REML) method of estimation.