A recent review found that patients with chronic obstructive pulmonary disease (COPD) were at increased risk for mild cognitive impairment and dementia.
A systematic review and meta-analysis published in World Journal of Clinical Cases found an elevated risk of dementia and mild cognitive impairment (MCI) among patients with chronic obstructive pulmonary disease (COPD).
The investigators searched the PubMed, Embase, Google Scholar, and Cochrane Library online databases for studies published prior to March 31, 2021.
Studies were included if they investigated the association between COPD and risk of MCI or dementia; adopted a definite outcome of cognitive impairment or dementia; reported raw values necessary to calculate odds ratio (OR) or HR; contained case controls, were prospective or retrospective-cohort, or had a cross-sectional design; and compared the association between patients with and without COPD. Studies were excluded if they did not report relevant outcomes or did not have the full text accessible.
The review included 27 studies published between 1996 and 2020. Ten were case-controlled, 10 were cross-sectional, 4 were prospective cohort, and 3 were retrospective cohort studies. The quality score, assessed by the Newcastle-Ottawa Scale, was high in 12 studies, medium in 7, and low in 6.
The 10 studies that investigated the association between COPD and MCI had 71,174 patients with COPD and 22,082 controls. The meta-analysis found a strong association between COPD and MCI (OR, 2.11; 95% CI, 1.32-3.38). There was significant heterogeneity and patients with COPD were 1.26 times more likely to have MCI than non-COPD controls.
There was a significant association between COPD and MCI (HR, 1.22; 95% CI, –1.18 to –1.27) when adjusted HRs were pooled from 4 studies.
The 7 studies that investigated COPD and dementia association had 108,606 patients with COPD and 347,939 controls. The meta-analysis found an increased risk of dementia in patients with COPD (OR, 1.16; 95% CI, 0.98-1.37) compared with non-COPD controls.
There was also a relationship between COPD and dementia when adjusted HRs were pooled from 6 studies (HR, 1.32; 95% CI, –1.22 to –1.43).
There were 17 studies that reported mean Mini-Mental State Examination (MMSE) scores for patients with COPD and those without; these included 1392 patients with COPD and 5097 controls. There was a significantly lower MMSE score, indicating worse cognition, in patients with COPD compared with controls (MD, –1.68; 95% CI, –2.66 to –0.71).
There were some limitations to this review. The studies included in this review had different designs, which may be a cause of heterogeneity. There were only 7 studies evaluating the relationship between COPD and dementia, which limits the results of this review. Heterogeneity may have been because of different geographical populations, variation of diagnostic criteria of COPD, and diversity in the factors for the multivariate analysis of the included studies.
The studies did not have long-term follow-up data that would help the researchers conduct subgroup analysis based on age, comorbidities, and gender. The included studies also used different methods of assessing and diagnosing COPD and cognitive impairment.
The researchers concluded that there was an elevated risk of MCI and dementia in patients with COPD.
“Proper clinical management and attention are necessary to prevent or mitigate the incidence of MCI and dementia in COPD patients,” the authors wrote.
Zhao LY, Zhou XL. Association of chronic obstructive pulmonary disease with mild cognitive impairment and dementia risk: a systematic review and meta-analysis. World J Clin Cases. 2022;10(11):3449-3460. doi:10.12998/wjcc.v10.i11.3449