COPD-Related Cognitive Impairment Unlike Other Forms of Dementia

In addition to the burden imposed by chronic obstructive pulmonary disease (COPD), patients often face co-occurring conditions such as diabetes, coronary artery disease, and osteoporosis.¹ Emerging research also indicates that cognitive impairment is a common comorbidity in COPD, with studies showing prevalence as high as 52% in this patient population.² “A number of suggestions have been made regarding the underlying pathophysiology, including cerebral hypoxia, loss of hippocampal volume and inflammatory mediator-related neuronal damage,” according to the results of a study published  in ERJ Open Research.²

As rates of cognitive impairment continue to increase due to the growing elderly population, it is especially important to elucidate the cognitive deficits associated with COPD and to differentiate these from the deficits observed in Alzheimer disease and other types of dementia. To that end, researchers conducted a narrative review and subsequent cross-sectional study to examine differences in the pattern of cognitive impairment in patients with COPD (n=44) compared with patients with Alzheimer-type dementia (n=17) and healthy controls (n=28). The Addenbrooke’s Cognitive Examination (ACE)-III was used to assess cognitive impairment and domain-specific deficits.²

According to the results, the prevalence of cognitive impairment was 50% (95% CI, 33.8%-66.2%) in patients with COPD vs 7% (95% CI, 9.0%-23.5%) in the control group. Significantly lower scores on the ACE-III were found in the COPD group vs controls (P <.001) and in the Alzheimer group compared with the COPD group (P =.019). In addition, the Alzheimer group demonstrated lower scores in the domains of attention (P =.004), memory (P =.004), and fluency (P =.001) compared with the COPD group.

In line with results from previous research,^3,4 the current findings point to a higher prevalence of cognitive impairment in patients with COPD vs healthy controls and suggest that there are domain-specific differences in COPD-related cognitive impairment compared with Alzheimer dementia. “If confirmed, this would be clinically relevant for COPD management (eg, it might alter the ability to comply with particular treatment types or benefit from more complex therapies) and for care of their comorbid disease, as specific types of cognitive impairment may have different management strategies,” the investigators wrote.²

To learn more about the link between COPD and cognitive impairment, Pulmonology Advisor interviewed one of the study coauthors, Charlotte Morris, BSc, MBBCh, a researcher at University Hospitals Birmingham NHS Foundation Trust (UHB) in the United Kingdom; and Balwinder Singh, MD, MS, FAPA, assistant professor of psychiatry in the department of psychiatry and psychology, and director of the Mood Program at the Mayo Clinic in Rochester, Minnesota, who has also investigated the topic with his colleagues.^3,4

Pulmonology Advisor: What is known thus far about cognitive impairment in COPD and what do your findings add to our understanding of this issue?

Dr Morris: There is increasing evidence in the published literature that patients with COPD are more likely to have cognitive impairment. What we do not know is whether people with COPD are more specifically affected in certain areas of cognition. Using a validated cognitive tool, we found that specific areas of cognition were affected differently in COPD compared with people with known Alzheimer-type dementia. We also found that when we compared the COPD group with the healthy control group, patients with COPD were significantly more likely to have cognitive impairment. 

Although these results are interesting and fit with results previously published in the literature, we must bear in mind that this was a small study and there could have been confounding effects.

Dr Singh: Patients with COPD have an increased risk for neuronal injury, either due to hypoxia or associated comorbidities, especially cardiovascular disease. Recent studies suggest that up to 77% of patients with both COPD and hypoxemia have some form of cognitive impairment.³ In a population-based, prospective cohort study of individuals aged 70 years and older (the Mayo Clinic Study of Aging), COPD was associated with a significant increase in the risk for incident mild cognitive impairment (MCI), specifically nonamnestic-MCI (na-MCI).³ The results remained significant after adjusting for several important covariates.

Further, there was a dose-response relationship: the risk for MCI increased with the duration of COPD. Thus, highlighting the importance of COPD as a risk factor for MCI may provide a substrate for early intervention to prevent the incidence or progression of MCI, particularly na-MCI.

Pulmonology Advisor: How should clinicians screen for and treat these issues in practice?

Dr Morris: My approach to this is to be more aware that people with COPD are at risk for cognitive impairment, and to consider testing for this if signs are shown by the patient and the patient agrees to be screened. Although there is no cure for cognitive impairment, early diagnosis and intervention could mean more appropriate support structures for individuals who are affected.