COPD Linked to Increased Risk of Mild Cognitive Decline

Patients with chronic obstructive pulmonary disease (COPD) are twice as likely to develop mild cognitive impairment (MCI) that may include memory loss, according to recent research published in JAMA Neurology.

“Few longitudinal studies have examined the relationship between COPD and the risk of developing MCI,” study author Michelle Mielke, PhD, told Internal Medicine World Report. “Identifying risk factors for MCI — the earliest symptomatic phase of Alzheimer’s disease (AD) — may help to identify ways to delay or prevent the onset of dementia, especially in the absence of a curative therapy for AD.”

Although COPD is potentially treatable and preventable, Mielke noted it is a progressive disease characterized by chronic airflow limitation that can cause hypoxemia, low oxygen, and hypercapnia, which can all increase the risk of MCI.

For their study, Mielke and her co-authors examined 1,425 patients aged 70-89 years who were randomly selected from the Mayo Clinic Study on Aging. All of patients were assessed via nurse interview, neurology examination, neuropsychological testing, and COPD diagnosis confirmation at baseline and every 15 months thereafter. Roughly 1,600 of the participants were deemed cognitively normal, though 317 had MCI, and 288 had COPD.

According to Mielke, “two cross-sectional studies reported a higher frequency of COPD among individuals with MCI; however, only one longitudinal study had been previously conducted.”

“The longitudinal study showed that a diagnosis of COPD in mid-life, but not late-life, was associated with risk of MCI or dementia, but COPD was assessed by self-report, and the type of MCI was not examined,” Mielke noted. “In contrast, the present study used medical record-confirmed diagnoses of COPD, used consensus-conferenced diagnoses of MCI, and examined COPD and risk of both amnestic MCI (A-MCI) and non-amnestic MCI (NA-MCI).”

At the conclusion of their study, Mielke and her colleagues found “COPD was primarily a risk factor for NA-MCI, (and there was) a dose-response relationship indicating that the longer a person had COPD, the greater their risk of developing MCI.”

In fact, those with COPD were nearly 2 times more likely to have NA-MCI, though the strongest relationship was discovered in patients whose COPD extended beyond 5 years. On the other hand, no association was found between COPD and A-MCI.

Of the 370 patients who developed MCI over the course of the study, 230 (62.2%) had A-MCI, 97 (26.2%) had NA-MCI, 27 (7.3%) had MCI of an unknown type, and 16 (4.3%) progressed from normal cognition to dementia between 2 visits. Those with COPD at baseline tended to be older men who reported current or former smoking with a higher frequency of coronary heart disease (CHD), hypertension, and stroke.

“It is important to aggressively treat COPD early in an effort to prevent or delay the onset of MCI,” Mielke urged physicians. “It is also important to regularly assess cognitive function among people who have COPD. People who are cognitively impaired may not be able to follow their medication schedule, (and) this could result in the worsening of their COPD and further worsening of their cognition, leading to a downward spiral.”