Patients with COPD are almost twice as likely to suffer from mild cognitive impairment (MCI) and its subtypes compared to those their age who do not have the respiratory disease, according to researchers at the Mayo Clinic.

In assessing 1927 individuals aged 70 to 89 years, 229 (72%) had amnestic (a-)MCI, and 88 (18%) had non-amnestic (na-)MCI. The 288 patients with COPD had a significantly higher frequency of MCI, at 27% compared with 15% in participants without COPD. The frequency of a-MCI and na-MCI were also significantly higher, at 19% versus 11% and 8% versus 4%, respectively.

After adjustment for a range of confounders, the odds for any MCI in patients with COPD were 87% greater than for participants without. The odds for a-MCI were also elevated for COPD patients overall, as well as when men and women were considered separately.

Investigators also noted a dose-response relationship. In patients who had COPD for 5 years or less, the odds ratio for MCI was 1.60 compared with 2.10 for those with COPD for more than 5 years. In a-MCI, the odds were increased a nonsignificant 1.43-fold in those with COPD for 5 years or less compared with a significant 2.37-fold for those with longer disease duration.

The authors believe the findings could be related to hypoxia, which may result in increased neuronal injury, as well as chronic inflammatory processes in COPD. They note that while cardiovascular comorbidities may also lead to cognitive impairment, their results were independent of this, suggesting the observed relationship was not due to confounding by risk factors such as vascular disease or stroke.