A Systematic Review on Predictors of Working Memory Training Responsiveness in Healthy Older Adults: Methodological Challenges and Future Directions

Abstract

Background: Research on predictors of working memory training responsiveness, which could help tailor cognitive interventions individually, is a timely topic in healthy aging. However, the findings are highly heterogeneous, reporting partly conflicting results following a broad spectrum of methodological approaches to answer the question “who benefits most” from working memory training. Objective: The present systematic review aimed to systematically investigate prognostic factors and models for working memory training responsiveness in healthy older adults. Method: Four online databases were searched up to October 2019 (MEDLINE Ovid, Web of Science, CENTRAL, and PsycINFO). The inclusion criteria for full texts were publication in a peer-reviewed journal in English/German, inclusion of healthy older individuals aged ≥55 years without any neurological and/or psychiatric diseases including cognitive impairment, and the investigation of prognostic factors and/or models for training responsiveness after targeted working memory training in terms of direct training effects, near-transfer effects to verbal and visuospatial working memory as well as far-transfer effects to other cognitive domains and behavioral variables. The study design was not limited to randomized controlled trials. Results: A total of 16 studies including n = 675 healthy older individuals with a mean age of 63.0–86.8 years were included in this review. Within these studies, five prognostic model approaches and 18 factor finding approaches were reported. Risk of bias was assessed using the Quality in Prognosis Studies checklist, indicating that important information, especially regarding the domains study attrition, study confounding, and statistical analysis and reporting, was lacking throughout many of the investigated studies. Age, education, intelligence, and baseline performance in working memory or other cognitive domains were frequently investigated predictors across studies. Conclusions: Given the methodological shortcomings of the included studies, no clear conclusions can be drawn, and emerging patterns of prognostic effects will have to survive sound methodological replication in future attempts to promote precision medicine approaches in the context of working memory training. Methodological considerations are discussed, and our findings are embedded to the cognitive aging literature, considering, for example, the cognitive reserve framework and the compensation vs. magnification account. The need for personalized cognitive prevention and intervention methods to counteract cognitive decline in the aging population is high and the potential enormous. Registration: PROSPERO, ID CRD42019142750.

Predicting Working Memory Training Responsiveness in Parkinson’s Disease: Both “System Hardware” and Room for Improvement Are Needed

“…27,28 This discrepancy regarding the direction of predictive effects and corresponding mechanisms might be dependent on the type of CT and the applied analytical approach. 23 As in Fellman and colleagues, 15 more educational years were predictive for more WMT related positive change in our cohort of patients with PD. Education might be a proxy for cognitive reserve, 57 which in terms of the magnification hypothesis enables individuals to engage in processes of plasticity.…”

“…45,46 However, contradicting findings in the CT literature exist in healthy older adults, which discuss that CT might be able to diminish the cognitive reserve disadvantage of lesseducated older adults. 23,58 Furthermore, the discussion can be taken to the next level, considering a higher cognitive reserve to be commonly associated with less cognitive deficits given the same brain pathology. 59 We did not find a significant predictive value of PD motor impairment, which can be considered a proxy to the amount of PD-related brain pathology.…”

“…Previous studies in healthy aging have, for example, investigated baseline performance, intelligence, age, and education as possible predictors of WMT responsiveness. 23 The results were summarized in a recent systematic review, 23 indicating large heterogeneity and several methodological shortcomings across studies. Even though only an elaborated individual participant data meta-analysis will be able to overcome the current research gaps regarding both general effectiveness and mechanisms of WMT responsiveness in healthy aging, the available evidence so far indicated that individuals with lower baseline performance, less education, younger age, and higher intelligence seemed to benefit most from WMT.…”

Characterizing Cognition in Everyday Life of Older Adults With Subjective Cognitive Decline

“…Our findings also suggest functional working memory difficulties, which can be mediated through metacognitive strategies such as self-talk (Hatzigeorgiadis & Galanis, 2017). Studies on working memory training for older adults have yielded mixed results, and this literature is too heterogeneous to draw conclusions for clinical practice (Ophey et al, 2020). Our findings further suggest that older adults with SCD would benefit from a treatment approach that aims to improve memory-related beliefs.…”

Effectiveness of Cognitive Stimulation Personalized by the Preexisting Cognitive Level in Older Adults

“…8,9 A recent systematic review recommends to conduct more clinical trials with longitudinal follow-ups that can address the question of whether cognitive interventions impact upon or alter the trajectory of non-normal cognitive decline. 10 Moreover, recent publications show the need to identify factors that allow professionals to provide more effective treatment options 11 based on individual characteristics of the study population (age, education, general cognitive ability, initial performance, etc) and if so, how 12 the preexisting cognitive level may help provide this effective personalized intervention. 13 Because of the aforementioned identified needs, the main aim of this study was to analyze whether a personalized intervention based on the individual's preexisting cognitive levels may be more effective in the short and long terms than a general cognitive training program.…”