COPD Linked with Mild Cognitive Impairment

A recent study found that mild cognitive impairment was more likely in patients who had COPD, especially in those who had COPD for longer than 5 years.

Older adults with chronic obstructive pulmonary disease (COPD) may be at increased risk for developing mild cognitive impairment and memory loss, according to a study published in the November 2013 issue of Mayo Clinic Proceedings. The study also found that the longer patients had COPD, the more likely they were to experience cognitive impairment.

From October 2004 to July 2007, adults aged 70 to 89 enrolled in the Mayo Clinic Study of Aging were randomly selected and followed in order to analyze the relationship between COPD and mild cognitive impairment and its subtypes. To identify cognitive impairment, all patients were interviewed by a nurse, underwent a neurological examination conducted by a physician, and completed neurophysiological testing given by a psychometrist. Mild cognitive impairment was then diagnosed by a panel based on standardized criteria and was further classified as amnestic or non-amnestic, depending on memory loss. Cases of COPD were identified and confirmed through medical records.

Of 1927 patients included in the study, 288 were diagnosed with COPD, and the results indicated that they were almost twice as likely to also be diagnosed with mild cognitive impairment as were those without COPD. After adjusting for age, sex, education, and other factors, 27% of COPD patients were diagnosed with mild cognitive impairment, compared with just 15% of patients without COPD. When the cognitive impairment subtypes were analyzed individually, COPD was associated with a significantly increased risk for amnestic mild cognitive impairment in both men and women separately and combined. However, the relationship between non-amnestic mild cognitive impairment and COPD was not significant.

The results also indicated that the longer a patient had lived with COPD, the more likely they were to have mild cognitive impairment. Patients who had COPD for 5 years or less had an odds ratio for mild cognitive impairment of 1.60, compared with an odds ratio of 2.10 in patients who had COPD for more than 5 years.

Although the association between COPD and mild cognitive impairment was strong, remaining significant after adjusting for comorbidities, the authors note that there were limitations to the study. COPD may have been underdiagnosed or over diagnosed, and the study population was predominately white. Despite these limitations, the strong results suggest that the association between COPD and cognitive impairment should be studied further.

“Additional longitudinal studies in population-based cohorts are needed to determine whether COPD is indeed associated with the risk of incident [mild cognitive impairment] and dementia,” the authors of the study conclude.