Statistical challenges in investigating prognostic factors for memory training success in healthy older adults: a systematic review

Article type
Authors
Roheger M1, Folkerts A1, Krohm F1, Skoetz N2, Kalbe E1
1Department of Medical Psychology/Neuropsychology and Gender studies & Center for Neuropsychological Diagnostics and Intervention (CeNDI), Faculty of Medicine and University Hospital Cologne
2Cochrane Haematological Malignancies, Faculty of Medicine and University Hospital Cologne
Abstract
Background: even in the absence of disease, the aging process is associated with a decline in cognitive functioning, a process that may lead to a loss of autonomy and quality of life. Recent meta-analyses and reviews show that cognitive training (CT) targeting memory functions can be effective in improving memory in healthy older individuals. However, one question that remains underinvestigated until now is: who benefits from memory training?

Objective: the main goal is to investigate prognostic factors for memory training success in healthy older adults and to report the different statistical procedures used for investigating prognostic factors in the literature.

Methods: we defined a prognostic factor as any measure that can be used to estimate the change of memory training improvement. We included prognostic factor and prognostic factor finding studies investigating prognostic factors on verbal and visual short-, as well as long-term memory after conducting memory training and also analysed different statistical methods to investigate prognostic factors.

Results: our search yielded 7421 results. We included 25 references that address prognostic factors of memory training success. Full-text screening revealed high between-study heterogeneity with regard to the assessment, statistical evaluation and reporting of the investigated prognostic factors. Studies use different concepts of dependent variables (change scores versus. post-test scores with pre-test correction) when defining memory training success, leading to contradictory results.

Conclusions: different statistical definitions of training success and the use of different statistical methods when investigating prognostic factors for memory training success in healthy older adults lead to high between-study heterogeneity and complicate the summary of individual study results in meta-analyses. Investigated predictors comprise sociodemographic variables, cognitive level at training entry, genetic parameters, personality traits and imaging parameters.

Patient or health care consumer involvement: considering the fact that prognostic factors for memory training success in healthy older adults have many potential uses (e.g. aiding treatment and lifestyle decisions, improving individual dementia risk prediction, providing new treatment options), systematic reviews and meta-analyses are urgently needed to summarize evidence about the prognostic value of particular factors. In a second step, we will test and re-evaluate identified prognostic factors in further memory trials.