Impact of exercise training on cognitive function in patients with COPD: a systematic review and meta-analysis of randomised controlled trials

Abstract

Objective: The aim of this study was to describe the characteristics of exercise therapies in randomised controlled trials (RCTs) targeted at improving cognitive function and to assess their efficacy in COPD.

Methods: We conducted a comprehensive search of eight databases, namely PubMed, Web of Science, Embase, Cochrane Library, Chinese Biomedical Literature Database, China National Knowledge Infrastructure, Wanfang and Weipu, covering the period from database construction to 23 April 2024. Our search specifically targeted RCTs studying the effects of exercise on cognitive functioning in COPD patients. Trials consisted of one or more exercise training interventions along with at least one cognitive outcome study. Two reviewers independently reviewed papers, extracted data and evaluated the research literature's quality using the Cochrane risk-of-bias assessment tool RoB 2.0 and the modified Jadad scale. Meta-analysis of Montreal Cognitive Assessment (MoCA) scores in the groups with and without exercise intervention was performed and subgroup analyses were undertaken to identify potential causes of heterogeneity.

Results: We included a total of nine studies that included 578 COPD patients (69% male). Each study demonstrated that patients improved significantly in at least one cognitive component following training. All current research focuses on attention, executive function, motor ability, mental capacity, verbal fluency, visuoconstructive abilities and memory. The results revealed that exercise significantly improved MoCA scores in COPD patients (standardised mean difference (SMD) 0.576 (95% CI 0.054-1.097); p=0.029). A subgroup analysis of the duration of each intervention revealed that exercise training with an intervention duration of >30 min significantly improved overall cognitive performance in COPD patients (SMD 0.499 (95% CI -0.165-1.163); p=0.000, I²=0.0%). A subgroup analysis of varied intervention durations revealed that 4 weeks of exercise training significantly improved overall cognitive performance in COPD patients (SMD 0.202 (95% CI -0.238-0.641); p=0.000, I²=0.0%). In addition, just one study had a year-long follow-up period.

Conclusion: Participation in exercise training, whether aerobic exercise alone or in combination with resistance or muscular strength, healthy qigong, dance or breathing exercises, can improve cognitive performance to varying degrees in people with COPD. Nonetheless, the findings should be regarded with caution due to the limitations of the included studies.

FIGURE 1

Literature screening process. CNKI: China National Knowledge Infrastructure; CBM: Chinese Biomedical Literature Database.

FIGURE 2

Analysis of the risk of bias in accordance with the Cochrane Collaboration guidelines: a) traffic light plot of bias assessment and b) weighted summary plot of overall type of bias.

FIGURE 3

Forest plot of meta-analysis of effect sizes for Montreal Cognitive Assessment scale scores. Weights are from random effects models. DL: DerSimonian–Laird.

FIGURE 4

Subgroup analysis of cognitive function outcomes by intervention duration. Weights and subgroup heterogeneity test are from random effects models. DL: DerSimonian–Laird.

FIGURE 5

Subgroup analysis of cognitive function outcomes by duration of each intervention. Weights and subgroup heterogeneity test are from random effects models. DL: DerSimonian–Laird.