Research shows that elderly patients with chronic obstructive pulmonary disease (COPD) are nearly twice as likely as those without to have mild cognitive impairment (MCI).
Balwinder Singh (Mayo Clinic, Rochester, Minnesota, USA) and colleagues studied 1927 individuals aged 70 to 89 years .
After assessment with the Clinical Dementia Rating, medical history review, neurologic examination, the Short Test of Mental Status, and the Unified Parkinson’s Disease Rating Scale, 317 (17%) participants were diagnosed with MCI. Of these, 229 (72%) had amnestic (a-)MCI, and 88 (18%) had non-amnestic (na-)MCI.
The team found that 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.
Additionally, the researchers report a dose–response relationship, such that the odds for MCI or a-MCI increased according to the duration of COPD. For example, 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-foldfor those with longer disease duration.
Writing in the Mayo Clinic Proceedings, Singh et al explain that theirs is one of only a few studies to examine MCI in COPD patients, while several previous studies have reported an increased risk for clinical cognitive dysfunction in those with the disease .
They suggest 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.
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