Cognitive and memory training in adults at risk of dementia: a systematic review.

Nicola J Gates,Maria A Fiatarone Singh,Michael Valenzuela,Perminder S Sachdev

doi:10.1186/1471-2318-11-55

Abstract

BackgroundEffective non-pharmacological cognitive interventions to prevent Alzheimer's dementia or slow its progression are an urgent international priority. The aim of this review was to evaluate cognitive training trials in individuals with mild cognitive impairment (MCI), and evaluate the efficacy of training in memory strategies or cognitive exercises to determine if cognitive training could benefit individuals at risk of developing dementia.MethodsA systematic review of eligible trials was undertaken, followed by effect size analysis. Cognitive training was differentiated from other cognitive interventions not meeting generally accepted definitions, and included both cognitive exercises and memory strategies.ResultsTen studies enrolling a total of 305 subjects met criteria for cognitive training in MCI. Only five of the studies were randomized controlled trials. Meta-analysis was not considered appropriate due to the heterogeneity of interventions. Moderate effects on memory outcomes were identified in seven trials. Cognitive exercises (relative effect sizes ranged from .10 to 1.21) may lead to greater benefits than memory strategies (.88 to -1.18) on memory.ConclusionsPrevious conclusions of a lack of efficacy for cognitive training in MCI may have been influenced by not clearly defining the intervention. Our systematic review found that cognitive exercises can produce moderate-to-large beneficial effects on memory-related outcomes. However, the number of high quality RCTs remains low, and so further trials must be a priority. Several suggestions for the better design of cognitive training trials are provided.

Highlights

Effective non-pharmacological cognitive interventions to prevent Alzheimer’s dementia or slow its progression are an urgent international priority
Ten studies met our criteria for cognitive training and mild cognitive impairment (MCI): 6 trials of cognitive exercises (3 RCTs, 2 UCTs, 1 NRCT) and 4 training in memory strategies (2 RCTs, 2 NRCTs)
The ten trials in MCI were analysed individually with sample characteristics described in Table 1, intervention and outcomes described in Table 2, and effect sizes presented in Tables 3 and 4

Summary

Introduction

Effective non-pharmacological cognitive interventions to prevent Alzheimer’s dementia or slow its progression are an urgent international priority. The aim of this review was to evaluate cognitive training trials in individuals with mild cognitive impairment (MCI), and evaluate the efficacy of training in memory strategies or cognitive exercises to determine if cognitive training could benefit individuals at risk of developing dementia. Development of preventative strategies for Alzheimer’s dementia (AD) is an international priority, with prevalence rates projected to increase by over 75% in the quarter of a century [1]. It is possible that participation in complex mental activities at older age may offer protection from cognitive decline and mitigate dementia risk. Given the confusion of terms, an operational definition has been advanced which delineates cognitive training from other interventions [16]: 1) repeated practice, 2) on problem activities, 3) using standardized tasks, and 4) that target specified cognitive domains

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