1. 1www.thelancet.com/respiratory Published online August 2, 2013 http://dx.doi.org/10.1016/S2213-2600(13)70163-2
Better care for patients with COPD and cognitive impairment
Carlijn A M Campman1
, Margriet M Sitskoorn1,2
Published online August 2, 2013, www.thelancet.com/respiratory
Article citation:
Carlijn AM Campman, Margriet M Sitskoorn. Better care for patients with COPD and cognitive impairment,
Lancet Respiratory Medicine, 1 September 2013 (Volume 1 Issue 7 Pages 504-506 DOI: 10.1016/S2213-2600(13)70163-2).
Corresponding Author:
Margriet M. Sitskoorn, PhD., Professor of Clinical Neuropsychology | Tilburg University, PO Box 90153, 5000 LE Tilburg,
Netherlands | m.m.sitskoorn@tilburguniversity.edu | Telephone +31-13-466 2497
Affiliations:
1
Dept of Cognitive neuropsychology, Tilburg University
2
CoRPS - Center of Research on Psychology in Somatic diseases
We declare that we have no conflicts of interest.
The importance of comorbidities for outcome variables, including daily functioning and quality of life,
in patients with chronic obstructive pulmonary disease (COPD) is increasingly acknowledged.1
Although this recognition has been an important step towards improved clinical care, we believe that
addressing cognitive impairment will result in additional improvement.
Many patients with COPD have cognitive impairments.2–4
Previous studies reported prevalence from
10·4% to 77%.2,3
Reasons for this variation across studies include the use of different diagnostic
criteria for cognitive dysfunctions and different cognitive tests.2,3,5
Villeneuve and colleagues6
were
some of the few researchers who studied the prevalence of cognitive dysfunction according to
validated diagnostic criteria. They reported that 16 (36%) of 45 patients with moderate-to-severe
COPD were diagnosed with mild cognitive impairment, compared with six (12%) of 50 healthy
controls;6
mild cognitive impairment is a risk factor for further cognitive decline and dementia.
Cognitive dysfunctions have been associated with difficulties in daily functioning,7
reduced treatment
adherence,8
and mortality.9
Despite their high incidence and the link with important outcome
measures, attention to cognitive dysfunctions in patients with COPD has been sparse. To adequately
assess cognitive dysfunction, clinicians need to be able to screen cognition efficiently. Assessment
should not be too time-intensive, but should be comprehensive enough to capture the wide variety
of cognitive dysfunctions possible and sensitive enough to show mild as well as severe dysfunctions.
A substantial number of the studies that investigated cognitive dysfunction in patients with COPD
used a short screening instrument called the mini mental state examination. Although this
instrument can detect severe cognitive dysfunction, it is not sensitive enough to screen for mild
cognitive impairment in patients with COPD.6
Thus, studies that used this instrument might have
underestimated the incidence of cognitive dysfunction in these patients. More appropriate screening
instruments should be used.
The Montreal cognitive assessment was shown to be of acceptable validity to screen for mild
cognitive impairment in patients with COPD.6
Computerised tests are another possibility. They are
often cost and time efficient, test a wider range of cognitive domains, and provide a better insight
into the degree of cognitive impairment than do short screening instruments such as the mini mental

2. 2www.thelancet.com/respiratory Published online August 2, 2013 http://dx.doi.org/10.1016/S2213-2600(13)70163-2
state examination and Montreal cognitive assessment. For example, some computerised tests (eg,
CNS vital signs neurocognitive test; CNS Vital Signs, Morrisville, NC, USA) take half an hour to
administer and examine a wide range of cognitive functions.10
A directly generated report provides
insight into possible cognitive deficits. Although this report cannot replace the diagnostic work of a
clinical neuropsychologist, it can provide clinicians with a way to rapidly screen for possible cognitive
deficits in their patients and it might be easier to implement in daily clinical care than traditional
cognitive assessments. Such tests should be validated in patients with COPD.
However, adequate diagnosis of cognitive deficiency alone is not sufficient. Additionally, more
knowledge about the underlying mechanisms of cognitive dysfunction in COPD is necessary. This
knowledge will enable us to predict which patients are at risk for development of cognitive
dysfunction and provide us with ideas about how to prevent and treat these cases. Pulmonary
dysfunction (eg, hypoxemia), which decreases oxygen supply to the brain, might partly explain
cognitive impairment. However, the weak relation between cognitive dysfunction and pulmonary
dysfunction3
and the existence of cognitive dysfunctions in non-hypoxemic patients with COPD11
suggest that there are likely to be other factors that contribute to cognitive impairment. Smoking
history, exercise capacity, depressed mood, and comorbid disorders such as cardiovascular disease
and sleep apnoea are all good candidates.3
These characteristics make people more vulnerable to
cognitive decline, whereas both a younger age and higher education level might protect people from
cognitive decline.12
Further research focused on individual characteristics and subgroups, with
longitudinal designs, is necessary.
According to WHO,13
improvement of treatment adherence will enhance the effectiveness of long-
term treatment for patients with chronic illness, including those with COPD, and ultimately reduce
health-care costs. Since a relation was shown between diminished treatment adherence and
cognitive impairment,8
treatment of these impairments could be an important way to enhance
treatment adherence, improve health, and reduce health-care costs in patients with COPD.
Unfortunately, treatment of cognitive dysfunction has not yet received much attention in COPD.
Guidelines for clinical care14
suggest that long-term oxygen therapy might improve cognitive
performance in hypoxemic patients. However, this suggestion is not always supported3
and there are
non-hypoxemic patients with cognitive dysfunction for whom treatment could also be beneficial.11
Multidisciplinary pulmonary rehabilitation might be another way to treat cognitive impairment.
Some of the studies dealing with this topic showed small improvement in cognitive functioning.15
However, firm conclusions about the effects of pulmonary rehabilitation on cognitive functioning
cannot yet be made because of the many components in these multidisciplinary programmes and the
small sample sizes of the studies. Thorough research on this topic is necessary.
Despite the high incidence of cognitive dysfunctions, and their link with treatment adherence, daily
functioning, and mortality, research into the consequences, the underlying mechanisms, and
treatment of cognitive dysfunctions in COPD is still in its infancy. Only two of 551 currently recruiting
trials registered in the WHO International Clinical Trials Registry Platform (accessed May 28, 2013)
enrolling patients with COPD have cognitive function as an outcome measure. We suggest that all
patients with COPD should be routinely screened for cognitive dysfunctions now that time and cost
efficient ways of testing are available. This improved recognition, combined with increased
knowledge of underlying mechanisms and increased treatment of cognitive impairment, will improve
clinical care and quality of life for patients with COPD.

3. 3www.thelancet.com/respiratory Published online August 2, 2013 http://dx.doi.org/10.1016/S2213-2600(13)70163-2
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