Cognitive Impairment Prevalence in COPD Population Rising Globally

A recent systematic review and meta-analysis identified an increase in the prevalence of cognitive impairment in the chronic obstructive pulmonary disease (COPD) population, with a variety of confounding factors influencing development.1

Cognitive impairment is measured over a series of degrees in one or more cognitive domains, including orientation, memory, calculations, language, executive function, reasoning, attention, and visuospatial function. Experts have divided it into mild cognitive impairment and dementia, based on its severity. Additionally, subjective cognitive decline, which refers to individuals experiencing memory loss or other cognitive functions while scoring normally on objective cognitive tests, is seen as a preliminary stage before mild cognitive impairment.2

“To our knowledge, only one study has systematically reported on the combined incidence of cognitive impairment in COPD patients,” wrote Ziwei Zhang, department of gastrointestinal surgery, Peking University Shenzhen Hospital, and colleagues. “Therefore, we conducted a comprehensive review and meta-analysis of the incidence and influencing factors of cognitive impairment in COPD populations in different regions of the world to understand the current trends in the occurrence of cognitive impairment in COPD and its risk factors, in order to provide a reference for the subsequent development of relevant clinical interventions.”1

Zhang and colleagues collected data from seven databases, including PubMed, Cochrane, Web of Science, Ovid, the Cochrane Library, Wiley, and Scopus, all through October 2022. Eligibility criteria included the following:

• Patients with COPD who have a confirmed diagnosis by a clinician
• Related articles on reporting the incidence of COPD patients and influencing factors
• A study that consisted of cross-sectional studies, cohort studies, and case-control studies

An initial total of 5264 studies were searched; investigators screened 1980 records for titles and abstracts after removing duplicates. Overall, 563 articles were reviewed in full, and 41 were included in the meta-analysis, consisting of 138,030 patients.1

Across the studies, COPD incidence was 20%-24% with significant heterogeneity (i2 = 99.8%, P = 0.0). A collective 8 studies reported the prevalence of mild cognitive impairment, with an overall combined prevalence of 24% (95% CI, 0.17-0.32) while still exhibiting heterogeneity between studies (i2 = 91.41%, P = 0.0).1

Meta-analysis showed that age (odds ratio [OR], 1.06; 95% CI, 1.04-1.09; P = .001), education (OR, 0.68; 95% CI, .47-.99, P = .044), coughing sputum (OR, 1.63; 95% CI, 1.34-1.99; P = 0.0), forced expiratory volume in 1 second (FEV1) (OR, 0.98; 95% CI, .96-.99, P = .001), partial pressure of oxygen (PaO2) (OR, 1.63; 95% CI, 1.34-1.99; P = 0.0), body-mass index, airflow obstruction, dyspnea, and exercise (BODE) index score (OR, 1.18; 95% CI, 1-1.4; P = .045), and depression (OR, 1.37; 95% CI, 1.16-1.61; P = 0.0) were all significant risk factors for cognitive impairment onset in COPD.1

Additionally, investigators stratified these data by patient cognitive impairment diagnostic criteria and assessment tools, indicating that cognitive impairment prevalence in COPD was 21% (95% CIC, .18-.25) in the Mini-Mental State Examination (MMSE) group, 39% (95% CI, .25-.52) in the Montreal Cognitive Assessment (MoCA) group, and 22% (95% CI, .09-.35) in groups using other toolsets. Stratification for region also indicated a prevalence of 19% (95% CI, 0.12-0.27) in North America, 15% (95% CI, 0.11-0.19) in Europe, 34% (95% CI, 0.24-0.43) in Asia, 56% (95% CI, 0.37-0.75) in Oceania, and 27% (95% CI, 0.17-0.37) in other regions.1

The team indicated several reasons for cognitive impairment's higher prevalence in Asia, indicating that lower levels of development and the need for public health policy improvement may be tied to the incidence of disease. Additionally, Zhang and colleagues noted that other risk factors, such as smoking, comorbid cardiovascular disease, and sleep disorders, were not analyzed in this study; to this end, they encourage further research.1

“In the future, screening for cognitive impairment in COPD patients and improving local public health policies should be strengthened to reduce the occurrence and development of cognitive impairment by early intervention in areas not covered by the study,” Zhang and colleagues wrote. “In addition, more socialized services for COPD patients should be developed, to improve the targeting of prevention and intervention.”1

References:

1. Zhang Z, Yang P, Xiao G, et al. Prevalence and Risk Factors of Cognitive Impairment in COPD: A Systematic Review and Meta-Analysis. Public Health Nurs. 2025;42(3):1389-1407. doi:10.1111/phn.13524

2. Ni X, Wu F, Song J, et al. Chinese expert consensus on assessment of cognitive impairment in the elderly. Aging Med (Milton). 2022;5(3):154-166. Published 2022 Oct 3. doi:10.1002/agm2.12222