COPD Linked to Cognitive Impairment

Chronic obstructive pulmonary disease (COPD) is an increasingly common respiratory disease, affecting as many as 14% of people over 75. It’s a combination of two condition, emphysema and chronic bronchitis, with smoking as it’s principal cause. Apart from the distressing difficulty in breathing, COPD worsens several conditions that are also common in old age – physical disability, cardiovascular disease, depression, and anxiety.

A study published in the American Journal of Respiratory and Critical Care Medicine reports a further problem that COPD sufferers may face: cognitive decline, or reduced mental functioning. Cognitive decline is a fairly common occurrence in old age, but it’s also seen after radiation for cancer and other ‘insults’.

Data came from 4,150 adults participating in the Health and Retirement Study, who had biennial surveys between 1992 and 2002. Cognitive testing was done on them in 1996 and in at least one subsequent survey/exam, using a 35-point validated cognitive performance scale. The average age of the participants at enrollment was 62, with 57% of them women and 82% white.

Among the 4,150 participants there were 492 (12%) who reported having COPD; 153 of them were classified as ‘severe’ cases. A severe rating meant that COPD limited their usual activities, or they were oxygen-dependent.

On repeated measurements, average cognition scale scores were2.6 points lower in severe COPD and 0.9 points lower in non-severe COPD patients, compared with those in non-COPD subjects. The difference for those with severe COPD remained statistically significant, even after adjustments were made for possible biasing factors (age, gender, education level, income, smoking, medications, other illnesses, etc).

The authors of the report recognize certain failings in their study: they were unable to determine the time-course of clinical diagnosis, and had no respiratory test results to quantify the degree of COPD. Nevertheless, their findings are important. People with cognitive difficulties are less likely to take their medications as prescribed or attend for follow-up exams, and may therefore deteriorate more rapidly. Early recognition of the problem is essential.