Evidence against benefits from cognitive training and transcranial direct current stimulation in healthy older adults

Abstract

Cognitive training and brain stimulation show promise for ameliorating age-related neurocognitive decline. However, evidence for this is controversial. In a Registered Report, we investigated the effects of these interventions, where 133 older adults were allocated to four groups (left prefrontal cortex anodal transcranial direct current stimulation (tDCS) with decision-making training, and three control groups) and trained over 5 days. They completed a task/questionnaire battery pre- and post-training, and at 1- and 3-month follow-ups. COMT and BDNF Val/Met polymorphisms were also assessed. Contrary to work in younger adults, there was evidence against tDCS-induced training enhancement on the decision-making task. Moreover, there was evidence against transfer of training gains to untrained tasks or everyday function measures at any post-intervention time points. As indicated by exploratory work, individual differences may have influenced outcomes. But, overall, the current decision-making training and tDCS protocol appears unlikely to lead to benefits for older adults.

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Fig. 1: CONSORT diagram.
Fig. 2: Decision-making task performance.
Fig. 3: Training performance.
Fig. 4: Far transfer task performance.
Fig. 5: Exploratory linear regressions.
Fig. 6: Exploratory genotype analyses.

Data availability

All data files are available at: https://osf.io/e2u73.

Code availability

Analysis code is provided at: https://osf.io/e2u73.

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Acknowledgements

We thank our research assistant A. Fox, who contributed substantially to data collection. P.E.D. and J.B.M. were supported by an ARC grant (DP180101885), H.L.F. by a UQ Fellowship (UQFEL1607881) and ARC Discovery Early Career Researcher Award (DE190100299). The funders had no role in study design, data collection and analysis, decision to publish or preparation of the manuscript.

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K.S.H. was involved in all aspects of the study, including study design, project planning, recruitment and data collection, data analysis and manuscript preparation. H.L.F. also contributed to each of these aspects. Z.E.N. contributed to project planning and data collection. Z.H. and K.P. were responsible for extraction and analysis of genetic data. J.B.M. contributed to study design and manuscript preparation. P.E.D. was involved in study design, project planning, data analysis and manuscript preparation.

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Correspondence to Kristina S. Horne.

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The authors declare no competing interests.

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Peer review information Primary handling editor: Anne Marike-Schiffer.

Extended data

Extended Data Fig. 1 Individual task and questionnaire statistics for one way ANOVA on baseline performance.

Note: BF >10 indicates strong support for H1 over H0; BF >3 indicates moderate support for H1 over H0; 1< BF <3 indicates anecdotal support for H1 over H0; 1/3< BF <1 indicates anecdotal support for H0 over H1; 1/10< BF <1/3 indicates moderate support for H0 over H1; BF <1/10 indicates strong evidence for H0 over H1; BF = 1 indicates no evidence for H0 or H1.

Extended Data Fig. 2 Individual task and questionnaire statistics for the group x time interaction for all time points.

Note: BF >10 indicates strong support for H1 over H0; BF >3 indicates moderate support for H1 over H0; 1< BF <3 indicates anecdotal support for H1 over H0; 1/3< BF <1 indicates anecdotal support for H0 over H1; 1/10< BF <1/3 indicates moderate support for H0 over H1; BF <1/10 indicates strong evidence for H0 over H1; BF = 1 indicates no evidence for H0 or H1.

Extended Data Fig. 3 Individual task statistics for the effect of genotype on baseline performance.

Note: COMT statistics are derived from one-way ANOVAs and BDNF statistics are derived from independent samples t-tests due to the exclusion of Met/Met alleles from analyses. BF >10 indicates strong support for H1 over H0; BF >3 indicates moderate support for H1 over H0; 1< BF <3 indicates anecdotal support for H1 over H0; 1/3< BF <1 indicates anecdotal support for H0 over H1; 1/10< BF <1/3 indicates moderate support for H0 over H1; BF <1/10 indicates strong evidence for H0 over H1; BF = 1 indicates no evidence for H0 or H1.

Extended Data Fig. 4 Individual task statistics for the genotype x group x time interaction.

Note: COMT statistics are derived from one-way ANOVAs and BDNF statistics are derived from independent samples t-tests due to the exclusion of Met/Met alleles from analyses. BF >10 indicates strong support for H1 over H0; BF >3 indicates moderate support for H1 over H0; 1< BF <3 indicates anecdotal support for H1 over H0; 1/3< BF <1 indicates anecdotal support for H0 over H1; 1/10< BF <1/3 indicates moderate support for H0 over H1; BF <1/10 indicates strong evidence for H0 over H1; BF = 1 indicates no evidence for H0 or H1.

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Supplementary Methods, Supplementary Figs. 1–16 and Supplementary References.

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Horne, K.S., Filmer, H.L., Nott, Z.E. et al. Evidence against benefits from cognitive training and transcranial direct current stimulation in healthy older adults. Nat Hum Behav 5, 146–158 (2021). https://doi.org/10.1038/s41562-020-00979-5

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