As the third leading cause of death in the United States, COPD affects about 13.7 million patients. Recent research has suggested that as many as 77% of patients with COPD and hypoxemia have some form of cognitive impairment. Despite this association, the link between COPD and mild cognitive impairment (MCI) has not been established in well-designed, population-based studies.
Investigating the Link
In a study published in Mayo Clinic Proceedings, Balwinder Singh, MD, MS, and colleagues analyzed data from 1,927 individuals aged 70 to 89 who participated in the Mayo Clinic Study of Aging to see if there was an association between COPD and MCI. Patients underwent a nurse assessment, neurological evaluation, and neuropsychological testing when they entered the study. A panel diagnosed MCI using standardized criteria and then reviewed medical records to identify people with COPD who developed MCI.
According to the analysis, patients with COPD had a higher prevalence of MCI than those without COPD (27% vs 15%). Findings were similar for both men and women involved in the study. “In addition, COPD was associated with almost two-fold higher odds of MCI,” says Dr. Singh. The associations of COPD with overall MCI and amnestic MCI were independent of age, sex, education, apolipoprotein E genotype, BMI, depression, and a history of coronary artery disease, diabetes, hypertension, and stroke.
The investigation also revealed that there appears to be a dose-response effect for COPD duration. “We observed a 1.60 odds ratio for MCI in patients who had COPD for 5 years or less, but this ratio jumped to 2.10 in patients who had a COPD duration that exceeded 5 years,” Dr. Singh says. “The longer that patients had COPD, the greater the likelihood that they developed MCI at some point in their life.” These findings occurred even after controlling for potential covariates.
Considering the Implications
Currently, there are no effective therapies to treat dementia, but identifying risk factors for the development of MCI can be of help. “If we can determine the factors that increase risks for MCI, we can possibly prevent or delay the progression of early cognitive changes to clinical dementia,” says Dr. Singh. “It appears that COPD is one of those risk factors.”
Dr. Singh notes that COPD is reversible when it is detected and treated in the early stages of the disease, especially in smokers. “Our results indicate that COPD potentially increases the odds of MCI and may provide a substrate for early intervention,” he says. “The hope is that patients who are diagnosed with COPD will be screened for MCI so that clinicians can provide interventions early. These early screenings may help us prevent MCI from developing or slow its progression.”
Singh B, Parsaik AK, Mielke MM, et al. Chronic obstructive pulmonary disease and association with mild cognitive impairment: the Mayo Clinic Study of Aging. Mayo Clin Proc. 2013;88:1222-1230. Available at: http://www.mayoclinicproceedings.org/article/S0025-6196(13)00731-3/fulltext.
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