Morphological and microstructural brain changes induced by cognitive training among non-demented participants: a...

Cognitive training is a widely recommended technique for cognitive decline and has been shown to improve cognitive functioning. However, the findings on its effect on objective biomarkers of cognitive impairment are highly ambiguous. This study therefore aims to clarify how cognitive training alters brain structure and physiology.

A systematic search was conducted in three databases (MEDLINE, Embase, and CENTRAL) for eligible articles in November 2023. The search identified 6.134 articles from which 501 remained after title and abstract selection. Eight articles were identified that assessed the efficacy of cognitive training on objective parameters in non-demented adults. Mean differences (MD) and standardized mean differences (SMD of changes between pre- and post-training data were calculated using random-effects models.

4767 records remained after the removal of duplicates. The selection process ended with 40 eligible articles for qualitative and 8 for quantitative analysis. We did not identify enough articles for the analysis of PET, functional MRI and fluid-based parameters. No significant differences were found in fractional anisotropy (MD=0.01, 95 % Confidence interval (CI): -0.01; 0.04) or in hippocampal volume (SMD=0.03, 95 % CI: -0.01; 0.06). Heterogeneity was high in all analyses.

Training groups showed no significant morphological or microstructural modifications compared to control conditions. The current results of objective markers are not powerful enough to recommend cognitive training as a preventive method. Future research should focus on proper randomization, elimination of baseline differences and use standardized techniques. The review was pre-registered with PROSPERO (ID: CRD42023485440).