Cognition-Oriented Treatments for Older Adults: a Systematic Overview of Systematic Reviews

Abstract

Cognition-oriented treatments - commonly categorized as cognitive training, cognitive rehabilitation and cognitive stimulation - are promising approaches for the prevention of cognitive and functional decline in older adults. We conducted a systematic overview of meta-analyses investigating the efficacy of cognition-oriented treatments on cognitive and non-cognitive outcomes in older adults with or without cognitive impairment. Review quality was assessed by A Measurement Tool to Assess Systematic Reviews 2 (AMSTAR). We identified 51 eligible reviews, 46 of which were included in the quantitative synthesis. The confidence ratings were "moderate" for 9 (20%), "low" for 13 (28%) and "critically low" for 24 (52%) of the 46 reviews. While most reviews provided pooled effect estimates for objective cognition, non-cognitive outcomes of potential relevance were more sparsely reported. The mean effect estimate on cognition was small for cognitive training in healthy older adults (mean Hedges' g = 0.32, range 0.13-0.64, 19 reviews), mild cognitive impairment (mean Hedges' g = 0.40, range 0.32-0.60, five reviews), and dementia (mean Hedges' g = 0.38, range 0.09-1.16, seven reviews), and small for cognitive stimulation in dementia (mean Hedges' g = 0.36, range 0.26-0.44, five reviews). Meta-regression revealed that higher AMSTAR score was associated with larger effect estimates for cognitive outcomes. The available evidence supports the efficacy of cognition-oriented treatments improving cognitive performance in older adults. The extent to which such effects are of clinical value remains unclear, due to the scarcity of high-quality evidence and heterogeneity in reported findings. An important avenue for future trials is to include relevant non-cognitive outcomes in a more consistent way and, for meta-analyses in the field, there is a need for better adherence to methodological standards. PROSPERO registration number: CRD42018084490.

Keywords: Cognitive rehabilitation; Cognitive stimulation; Cognitive training; Older adults; Overview; Systematic review.

Fig. 1

PRISMA flow chart

Fig. 2

Number of meta-analyses (percent) that adhered to the AMSTAR items AMSTAR = a measurement tool to assess systematic reviews; PICO = population, intervention, comparator group, outcome; RoB = risk of bias.

Fig. 3

Pooled results of meta-analyses investigating objective cognitive outcomes of cognition-oriented treatments (COT) in older adults. Positive values represent an improvement favouring the intervention group. k represents the number of primary trials included in the analysis. If a review reported several effect sizes within each outcome domain, a composite was created and k denotes the range of the number of primary trials that contributed to the effect estimate. AMSTAR = a measurement tool to assess systematic reviews (max score 16); OA = older adults; MCI = mild cognitive impairment; PD = Parkinson’s disease.* total number of studies in review.

Fig. 4

Pooled results of meta-analyses investigating subjective cognitive, psychosocial, functional, caregiver and clinical outcomes of cognition-oriented treatments (COT) in older adults. Positive values represent an improvement favouring the intervention group. k represents the number of primary trials included in the analysis. If a review reported several effect sizes within each outcome domain, a composite was created and k denotes the range of the number of primary trials that contributed to the effect estimate. AMSTAR = a measurement tool to assess systematic reviews (max score 16); OA = older adults; MCI = mild cognitive impairment; PD = Parkinson’s disease. * total number of studies in review.

Fig. 5

Association between objective cognition effect size and (a) AMSTAR score, (b) year of publication and (c) number of included studies. Circle size refer to the number of included studies. Two extreme effect sizes (Folkerts et al., ; Gates, Rutjes, et al., 2019) were omitted from the scatterplots. AMSTAR = a measurement tool to assess systematic reviews.