Older adults diagnosed with chronic obstructive pulmonary disease may be at a higher risk for mild cognitive impairment, which can eventually lead to Alzheimer’s disease, according to a new study published in JAMA Neurology.
“Chronic obstructive pulmonary disease (COPD), while progressive, is a potentially treatable and preventive disease characterized by chronic airflow limitation,” study author Michelle M. Mielke told Healthline. “Chronic airflow limitation can cause hypoxemia and hypercapnia. These conditions could increase the risk of cognitive impairment. However, few longitudinal studies examining the relationship between COPD and the risk of developing mild cognitive impairment (MCI) have been conducted.”
There has also been limited research as to whether the relationship between COPD and MCI is specific to the type of MCI patients develop.
Two Kinds of Mild Cognitive Impairment
Two types of MCI exist, each classified by the thinking skills affected.
The first is known as amnestic MCI, which affects memory and may cause a person to forget information easily recalled in the past, like recent events or conversations. The second is non-amnestic MCI, which affects thinking skills other than memory, including the ability to make level-headed decisions, judge the time, or conceptualize the steps needed to complete a certain task, according to the Alzheimer’s Association.
“We found that COPD was primarily a risk factor for non-amnestic MCI," Mielke said. "We also found a dose-response relationship indicating that the longer a person had COPD, the greater their risk of developing MCI.”
According to study authors, older adults who had COPD for more than five years had the greatest risk of developing MCI.
“These findings highlight the importance of COPD as a risk factor for MCI and may provide a substrate for early intervention to prevent or delay the onset and progression of MCI, particularly non-amnestic type,” the study authors wrote.
Researching the Relationship Between COPD and MCI
In order to determine the association between COPD and MCI, researchers examined 1,425 people, ages 70 to 89, from Olmsted County, Minn., with normal cognition in 2004. At baseline, 171 patients had been diagnosed with COPD. Out of all the participants, a total of 370 developed MCI: 230 had amnestic MCI and 97 had non-amnestic MCI. Twenty-seven patients had MCI of an unknown type and 16 developed dementia.
After about five years, researchers followed up and determined that COPD increased the risk for non-amnestic MCI by about 83 percent. The patients who had COPD for more than five years had the greatest risk for MCI.
“This research further suggests that COPD is associated with risk of MCI,” Mielke said. “A next step is to understand the exact mechanisms by which COPD increases the risk of MCI.”
The Impact of COPD and MCI in the U.S.
COPD is the third leading cause of death in the U.S., according to the National Heart, Lung and Blood Institute (NHLBI). It affects more than 13.5 million U.S. adults 25 years and older, according to current surveillance data, study authors wrote. COPD is also a major cause of disability and can prevent a person from doing even the most basic daily tasks, according to the NHLBI.
MCI is also prevalent in the U.S., affecting about 10 to 20 percent of those aged 65 and older, according to the Alzheimer’s Association. It can also lead to Alzheimer’s disease, which affects more than 5 million Americans and is the sixth leading cause of death in the U.S., according to the Alzheimer’s Association.
“Identifying risk factors for MCI, the earliest symptomatic phase of Alzheimer’s disease, may help to identify ways to delay or prevent the onset of dementia, especially in the absence of a curative therapy for Alzheimer’s disease,” Mielke said.
Causes, Symptoms and Prevention of COPD
While there is currently no cure for COPD, certain lifestyle changes and treatments can help prevent and slow progression of the disease.
“It is important to aggressively treat COPD early, in an effort to prevent or delay the onset of MCI,” Mielke said. “It is also important to regularly assess cognitive function among people who have COPD.”
Cigarette smoking is one of the main causes of COPD. But long-term exposure to lung irritants like pollution, chemical fumes, or dust can also lead to COPD.
Symptoms of COPD vary for each individual, but some of the most common signs, according to the NHLBI, include: an ongoing cough, or a cough that produces a lot of mucus, shortness of breath, especially during physical activity, chest tightness and wheezing.
“Lifestyle is important and may help to prevent or delay both COPD or MCI,” Mielke said. “This includes regular exercise, eating right and maintaining a healthy weight and not smoking.”
For those who have been diagnosed with MCI, the Alzheimer’s Associations suggests regular exercise, controlling cardiovascular risk factors, and participating in mentally stimulating and socially engaging activities to help slow the progression of mental decline.