ABSTRACT
Training interventions for older adults are designed to remediate performance on trained tasks and to generalize, or transfer, to untrained tasks. Evidence for transfer is typically based on the trained group showing greater improvement than controls on untrained tasks, or on a correlation between gains in training and in transfer tasks. However, this ignores potential correlational relationships between trained and untrained tasks that exist before training. By accounting for crossed (trained and untrained) and lagged (pre-training and post-training) and cross-lagged relationships between trained and untrained scores in structural equation models, the training-transfer gain relationship can be independently estimated. Transfer is confirmed if only the trained but not control participants' gain correlation is significant. Modeling data from the Improvement in Memory with Plasticity-based Adaptive Cognitive Training (IMPACT) study (Smith et al., 2009), transfer from speeded auditory discrimination and syllable span to list and text memory and to working memory was demonstrated in 487 adults aged 65-93. Evaluation of age, sex, and education on pretest scores and on change did not alter this. The overlap of the training with transfer measures was also investigated to evaluate the hypothesis that performance gains in a non-verbal speeded auditory discrimination task may be associated with gains on fewer tasks than gains in a verbal working memory task. Gains in speeded processing were associated with gains on one list memory measure. Syllable span gains were associated with improvement in difficult list recall, story recall, and working memory factor scores. Findings confirmed that more overlap with task demands was associated with gains to more of the tasks assessed, suggesting that transfer effects are related to task overlap in multimodal training.
ABSTRACT
OBJECTIVES: To examine whether therapeutic interventions of extended practice of cognitive tasks or aerobic exercise have led to significant improvement in untrained cognitive tasks. DESIGN: The PSYCINFO, MEDLINE, and Abstracts in Social Gerontology databases were searched for English-language studies of cognitive interventions of exercise or extended cognitive practice between 1966 and 2010. The final search was in January 2011. Studies included were experimental interventions hypothesizing improvement on untrained cognitive outcomes with pre- and posttests. Studies of varying quality were included and compared. SETTING: Interventions generally took place in laboratories, in gymnasium facilities, in the home, and outdoors. Experimenters administered testing. PARTICIPANTS: Forty-two studies with 3,781 healthy older adults aged 55 and older were analyzed. MEASUREMENTS: Between-group effect sizes (ESs), which account for practice effects on outcome measures, and within-experimental group ESs were computed from untrained cognitive outcome domains, including choice reaction time, memory, and executive function, and compared. ESs were also coded for training type and study quality. Multilevel mixed-effect analyses accommodated multiple outcomes from individual studies. RESULTS: Extended practice (estimated ES = 0.33, 95% confidence interval (CI) = 0.13-0.52) and aerobic fitness (estimated ES = 0.33, 95% CI = 0.10-0.55) training produced significant between-group ESs, but they did not differ in magnitude. Better study quality was associated with larger ESs. CONCLUSION: Findings indicate that aerobic and extended cognitive practice training interventions for healthy older adults improve performance on untrained cognitive tasks.