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Clinician Article

The effectiveness of physical exercise on cognitive and psychological outcomes in individuals with mild cognitive impairment: A systematic review and meta-analysis.



  • Song D
  • Yu DSF
  • Li PWC
  • Lei Y
Int J Nurs Stud. 2018 Mar;79:155-164. doi: 10.1016/j.ijnurstu.2018.01.002. Epub 2018 Jan 4. (Review)
PMID: 29334638
Read abstract Read evidence summary
Disciplines
  • Neurology
    Relevance - 6/7
    Newsworthiness - 6/7
  • Geriatrics
    Relevance - 6/7
    Newsworthiness - 4/7
  • Family Medicine (FM)/General Practice (GP)
    Relevance - 5/7
    Newsworthiness - 3/7
  • General Internal Medicine-Primary Care(US)
    Relevance - 5/7
    Newsworthiness - 3/7

Abstract

OBJECTIVE: Individuals with mild cognitive impairment (MCI) are at high risk for developing dementia. Physical exercise is a promising intervention for cognitive decline. Systematic reviews regarding the effects of physical exercise on cognitive and psychological outcomes among MCI patients are limited, and a systematic review exploring the effects of exercise modalities on the results has not been conducted. This study evaluated the effects of physical exercise on cognitive and psychological outcomes for MCI patients and attempted to identify which specific modality of exercise is more effective.

DESIGN: Systematic review and meta-analysis.

DATA SOURCES: A systematic search of Medline, CINAHL, EMBASE, PsycINFO, SPORTDiscus, and the China National Knowledge Infrastructure was performed.

REVIEW METHODS: Two reviewers independently assessed the study quality using the Effective Public Health Practice Project Quality Assessment Tool. Meta-analysis was conducted when data were available, with further subgroup analyses for exercise types. A series of sensitivity analyses were conducted to explore the influence of study quality and control types on the primary outcome. A narrative analysis was performed when statistical synthesis was inappropriate.

RESULTS: Eleven studies met the inclusion criteria. The exercise interventions can be classified into three types: (a) aerobic exercise, (b) resistance exercise, and (c) multi-modal exercise. Results showed that physical exercise had beneficial effects for global cognition [standard mean difference (SMD) = 0.30, 95% confidence interval (CI): 0.10-0.49, p = 0.002]. Further subgroup analysis demonstrated that aerobic exercise programmes are consistently associated with medium effect size (SMD: 0.54-0.58). However, the effects of physical exercise on domain-specific cognitive function and psychological outcomes in MCI patients remain inconclusive. Results of sensitivity analysis indicated that types of control exert influence on the outcomes.

CONCLUSIONS: Physical exercise, aerobic exercise in particular, benefits global cognition in MCI patients. The evidence of physical exercise on domain-specific cognitive function and psychological outcomes remains unclear, more trials with rigorous study design are necessary to provide the evidence.


Clinical Comments

Family Medicine (FM)/General Practice (GP)

Call me very skeptical. The larger the n of the analyzed studies, the less effect seen. Only 3 of the studies had more than 40 patients in each arm. By far the largest study (278 total patients studied) showed no trend toward benefit at all. This paper could easily be a case of meta-analysis producing a false positive result. Additionally, the difference is identified as small. So a small difference in a meta=analysis of several small studies with the only study of significant size having a very negative result makes me think this meta-analyis is only hypothesis raising and needs confirmed with a robust randomized controlled trial.

General Internal Medicine-Primary Care(US)

This systematic review looks to garner the evidence on physical exercise and cognitive outcomes in patients with mild cognitive impairment. The study pulled on 11 studies, of which 8 were of strong to moderate quality, many were of heterogeneous design, recruitment, and assessment. Aerobic exercise programmes were reported to be consistently associated with medium effect size - the clinical relevance of this effect size is however not clear. The systematic review however at minimum supports that aerobic exercise may serve to stabilise the cognitive status of patients with MCI, and builds up on the evidence of beneficial health outcomes for older adults.

Geriatrics

This was a systematic review and meta-analysis that evaluated the effects of physical exercise on cognitive and psychological outcomes for MCI patients. Eleven studies were included in the final review. The authors concluded that physical exercise had beneficial effects for global cognition [standard mean difference = 0.30; p = 0.002], with aerobic exercise demonstrating the most consistent benefit. The effect on specific cognitive domains was uncertain. Many physicians are already aware of this literature, but this article helps reinforce the message that exercise is beneficial in MCI. The small number of studies included limits the strength of the findings.

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