The Training Effect of Working Memory Based on Central Executive System Intervention in Older Adults: A Randomized Controlled Study

Effects of engagement, persistence and adherence on cognitive training outcomes in older adults with and without cognitive impairment: a systematic review and meta-analysis of randomised controlled trials

BACKGROUND

Limited understanding exists regarding the influences of engagement, persistence and adherence on the efficacy of cognitive training for age-related cognitive decline and neurodegenerative cognitive impairment.

METHODS

This study conducted a meta-analysis of randomised controlled trials (RCTs). We systematically searched MEDLINE, PubMed, Web of Science, Embase and CINAHL databases from 1 January 2012 to 13 June 2023, and included RCTs assessing the effects of cognitive training in older adults, both with and without cognitive impairment. Hedges' g with a 95% confidence interval (CI) was used to synthesise cognitive training effect sizes on various neuropsychological tests. Subgroup analyses were conducted based on variables including engagement, persistence, adherence and cognitive conditions of normal cognition, mild cognitive impairment (MCI) or neurodegenerative dementia.

RESULTS

This meta-analysis included 55 RCTs with 4,455 participants with cognitive conditions spanning normal cognition, MCI and neurodegenerative dementia. The mean age of participants was 73.9 (range: 65.7-84.5) years. Overall, cognitive training showed a significant cross-domain effect (Hedges' g = 0.286, 95% CI: 0.224-0.348). Training effects are significant when engagement or persistence rates exceed 60% or when adherence rates exceed 80%. Higher levels of persistence are required to achieve significant training effects in memory, visuospatial ability and reasoning than in executive function and attention and language. Higher persistence is also required for older adults with normal cognition to achieve significant training gains compared to those with cognitive impairment.

CONCLUSIONS

This systematic review highlights the critical roles of engagement, persistence and adherence in augmenting the efficacy of cognitive training.

Subject-performed task effect on working memory performance in children with autism spectrum disorder

A previous study found that children with autism spectrum disorder (ASD) have better recall when they perform instructions (subject-performed task [SPT]) than when they passively hear instructions (verbal task [VT]) in a working memory task for instructions, an effect that is called the SPT effect. This study explored whether the SPT effect exhibited by ASD children is caused by the movement component or by processing materials twice. More importantly, this study explored whether intelligence influences the SPT effect exhibited by ASD children. ASD children with three levels of intelligence (N = 56) and a control group, children with intellectual disability (ID) who had low intelligence but did not have ASD (N = 21), were asked to perform working memory tasks for instructions under VT, SPT and repeated (hearing the instruction twice) conditions. No significant difference in performance was observed between the VT and repeated conditions, regardless of the child's level of intelligence. ASD children with lower-middle intelligence exhibited a smaller SPT effect than ASD children with upper-middle intelligence. Critically, while ASD children with low intelligence did not exhibit the SPT effect, an ID group with equivalent low intelligence did show this effect. Therefore, these results show that the SPT effect for ASD children is caused by the movement component and is uniquely associated with a certain level of intelligence, namely, lower middle and higher levels of intelligence. LAY SUMMARY: In ASD children, the benefit of physically performing instructions for working memory performance is uniquely associated with a certain level of intelligence. Only ASD children with lower-middle intelligence (and higher) benefit from physically performing instructions, and higher intelligence increases this benefit; ASD children with low intelligence do not show this benefit. This benefit in ASD children is attributed to the additional motoric code generated by physical performance.

The Role of Sensory Function in Processing Speed and Working Memory Aging

BACKGROUND

Sensory function, processing speed, and working memory are considered to be mechanisms that play important explanatory roles in age-related decline of cognitive abilities. As individuals age, sensory function declines along with other cognitive abilities, including processing speed and working memory. Moreover, the relationship between sensory function, processing speed, and working memory, which represent the most basic mechanism, is one of the important issues in the field of cognitive aging.

METHODS

To explore the role of sensory function, especially visual function, in processing speed and working memory aging, the present study adopted a 2 (age: young and old) × 4 (visual perceptual stress: high, medium, low, and non-stress) mixed design and explored age differences in tasks testing processing speed and working memory. To generate different levels of visual perceptual stress, test materials were masked with Gaussian noise according to each individual's visual function.

RESULTS

The results indicated that age differences in processing speed were not influenced by different levels of visual perceptual stress, while age differences in working memory performance decreased gradually with the increase of visual perceptual stress.

CONCLUSION

Visual function affected age differences in working memory rather than in processing speed. The common-cause hypothesis and information-degradation hypothesis were applied to interpret the relationships between visual function and processing speed and between visual function and working memory, respectively. Moreover, sensory function may not directly affect working memory function, which was also consistent with a resource decrement model of aging.

Cognitive Interventions for Cognitively Healthy, Mildly Impaired, and Mixed Samples of Older Adults: A Systematic Review and Meta-Analysis of Randomized-Controlled Trials

Cognitive interventions may improve cognition, delay age-related cognitive declines, and improve quality of life for older adults. The current meta-analysis was conducted to update and expand previous work on the efficacy of cognitive interventions for older adults and to examine the impact of key demographic and methodological variables. EBSCOhost and Embase online databases and reference lists were searched to identify relevant randomized-controlled trials (RCTs) of cognitive interventions for cognitively healthy or mildly impaired (MCI) older adults (60+ years). Interventions trained a single cognitive domain (e.g., memory) or were multi-domain training, and outcomes were assessed immediately post-intervention using standard neuropsychological tests. In total, 279 effects from 97 studies were pooled based on a random-effects model and expressed as Hedges' g (unbiased). Overall, results indicated that cognitive interventions produce a small, but significant, improvement in the cognitive functioning of older adults, relative to active and passive control groups (g = 0.298, p < .001, 95% CI = 0.248-0.347). These results were confirmed using multi-level analyses adjusting for nesting of effect sizes within studies (g = 0.362, p < .001, 95% CI = 0.275, 0.449). Age, education, and cognitive status (healthy vs. MCI) were not significant moderators. Working memory interventions proved most effective (g = 0.479), though memory, processing speed, and multi-domain interventions also significantly improved cognition. Effects were larger for directly trained outcomes but were also significant for non-trained outcomes (i.e., "transfer effects"). Implications for future research and clinical practice are discussed. This project was pre-registered with PROSPERO (#42016038386).

Working Memory Training Does Not Improve Performance on Measures of Intelligence or Other Measures of "Far Transfer": Evidence From a Meta-Analytic Review

It has been claimed that working memory training programs produce diverse beneficial effects. This article presents a meta-analysis of working memory training studies (with a pretest-posttest design and a control group) that have examined transfer to other measures (nonverbal ability, verbal ability, word decoding, reading comprehension, or arithmetic; 87 publications with 145 experimental comparisons). Immediately following training there were reliable improvements on measures of intermediate transfer (verbal and visuospatial working memory). For measures of far transfer (nonverbal ability, verbal ability, word decoding, reading comprehension, arithmetic) there was no convincing evidence of any reliable improvements when working memory training was compared with a treated control condition. Furthermore, mediation analyses indicated that across studies, the degree of improvement on working memory measures was not related to the magnitude of far-transfer effects found. Finally, analysis of publication bias shows that there is no evidential value from the studies of working memory training using treated controls. The authors conclude that working memory training programs appear to produce short-term, specific training effects that do not generalize to measures of "real-world" cognitive skills. These results seriously question the practical and theoretical importance of current computerized working memory programs as methods of training working memory skills.