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

Study Overview
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Brief Summary
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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
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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.

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

Conditions
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Cognitive Aging

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


Participation Criteria
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Eligibility Criteria
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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.

Ages Eligible for Study
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Minimum Age: 60 Years
Maximum Age: 90 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Basic Science
Allocation: Randomized
Intervention Model: Factorial Assignment
Masking: Single


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Different Mixed Condition (DM)<br>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). | Behavioral: Different Mixed Condition (DM)<br>* Participants engage in home-based training on two working memory tasks, both different from those in the target task training. Goal is 10 days of training, with 4 8-min blocks of training each day.<br>|
| Experimental: Different Single Condition (DS)<br>Training in the Lexical Decision Span in Phase 1 (which is different from the target task Reading Span in Phase 2). | Behavioral: Different Single Condition (DS)<br>* Participants engage in home-based training on a working memory task that is different from that in the target task training. Goal is 10 days of training, with 4 8-min blocks of training each day.<br>|
| Active Comparator: Same Task (ST) Practice Control<br>Training in Reading Span task in Phase 1 (which is the same as target task in Phase 2). | Behavioral: Same Task (ST) Practice Control<br>* Participants engage in home-based training on the exact same working memory tasks as that in the target task training. Goal is 10 days of training, with 4 8-min blocks of training each day.<br>|
| Placebo Comparator: Non-WM Placebo Control (PC)<br>Training in a speeded Lexical Decision task only (which has no memory component) in Phase 1 prior to Phase 2 training in WM. | Behavioral: Non-WM Placebo Control (PC)<br>* Participants engage in home-based training on speeded verbal decision, which unlike the target task training, has no memory component. Goal is 10 days of training, with 4 8-min blocks of training each day.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Training gains on the Reading Span Task in Phase 2 | In Phase 2, training data on the target task is collected over 10 days. Learning curves are modeled with log function WM = Int + Coeff * ln(Trails). The coefficient is the primary outcome measure. | 2 weeks | 
| Change in Working Memory | Reading Span, Lexical Decision Span, Category Span, Operation Span, Count Span | Baseline and 5-6 weeks after pretest (1 hour each session) | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in Episodic Memory | Hopkins Verbal Learning Task (HVLT) | Baseline and 5-6 weeks after pretest (20 min each session) | 
| Change in Associative Memory | Paired associate recall task modeled on the HVLT | Baseline and 5-6 weeks after pretest (20 min each session) |