COPD Strongly Associated with Cognitive Deterioration

According to study results published in the International Journal of COPD, researchers found chronic obstructive pulmonary disease (COPD) patients had the highest cognitive deterioration rates compared to patients who were asymptomatic smokers (AS) or had chronic non-obstructive bronchitis (CNOB).

For their study, Italian researchers enrolled 402 patients (COPD n=229, CNOB n=127, and AS n=46) and used the Mini Mental Status test (MMSE) to assess patients’ time orientation, attention, and calculation (normal score: greater than or equal to 27 points; moderate cognitive impairment: 24—18 points; severe cognitive impairment: less than 18 points); the Clock Drawing test to gauge memory and symbolic representation (normal score: 7–10 points; cognitive impairment: less than 6 points); Trail Making test (TMT) to gauge visual processing and reproduction of numeric sequences (cognitive impairment: greater than or equal to 94 seconds); and the TMT B test to measure cognition flexibility, and shifting capacity skills (cognitive impairment: greater than or equal to 283 seconds).

To find a possible link, the researchers created multiple regression models between cognitive impairment (P<0.005 indicated statistical significance) and the patient’s age, sex, body mass index (BMI), smoking habit, forced expiratory volume in the first second (FEV1), FEV1/forced vital capacity (FVC), arterial partial pressure of O2 (PaO2) and CO2 (PaCO2), CAT score, MRC score, and possible comorbid conditions.

Based on their analysis, the investigators noted COPD patients had the highest cognitive deterioration rate, followed by CNOB and AS subjects (P<0.001). Furthermore, the writers found forced expiratory volume in the first second, and arterial partial pressure of O₂ and of CO₂ was associated with cognitive deterioration. Specifically, COPD, CNOB, and AS subjects aged 40—69 years had the most accelerated rates of cognitive impairment (P<0.01 compared to normal values), with the trend being especially pronounced in COPD subjects.

“Cognition can deteriorate substantially in subjects with chronic airway flow limitation (ie, COPD subjects), but also in subjects with other milder persistent airway disorders (ie, CNOB subjects and AS). The extent and the prevalence of this deterioration were directly related to the severity of the respiratory impairment,” the authors noted.

Despite their overarching discovery, the investigators recommended additional research be conducted further exploring chronic airway disorders and their effect on other aspects of cognition.