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Sylvia Villeneuve, PhD; Véronique Pepin, PhD; Nadia Gosselin, PhD; Katia Gagnon, BSc; Jean-François Gagnon, PhD
Author and Funding Information

From Helen Wills Neuroscience Institute (Dr Villeneuve), University of California, Berkeley; Centre de recherche (Drs Pepin, Gosselin, and Gagnon and Ms Gagnon), Hôpital du Sacré-Coeur de Montréal; the Department of Exercise Science (Dr Pepin), Concordia University; the Department of Psychiatry (Dr Gosselin), Université de Montréal; and the Department of Psychology (Dr Gagnon and Ms Gagnon), Université du Québec à Montréal.

Correspondence to: Jean-François Gagnon, PhD, Centre d’Études Avancées en Médecine du Sommeil, Hôpital du Sacré-Cœur de Montréal, 5400 boul. Gouin ouest, Montréal, QC, H4J 1C5, Canada; e-mail: gagnon.jean-francois.2@uqam.ca


Financial/nonfinancial disclosures: The authors have reported to CHEST the following conflicts of interest: Dr Pepin has received honoraria from GlaxoSmithKline for serving on the ADC113877 steering committee. Ms Gagnon and Drs Villeneuve, Gosselin, and Gagnon have reported that no potential conflicts of interest exist with any companies/organizations whose products or services may be discussed in this article.

Reproduction of this article is prohibited without written permission from the American College of Chest Physicians. See online for more details.


Chest. 2013;143(5):1512-1513. doi:10.1378/chest.13-0094
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Published online
To the Editor:

We thank Dr Damiani and colleagues for their constructive comments on our article in CHEST.1 They suggested a potential role of obstructive sleep apnea (OSA) in cognitive impairment reported among patients with COPD. It is indeed well established that OSA is associated with cognitive impairment; in fact, OSA was recently described as a risk factor for the development of mild cognitive impairment (MCI) and dementia in elderly individuals.2 Moreover, a pilot study conducted by our group showed a high frequency of MCI in adults with OSA (38%).3 This frequency is similar to that which we reported in patients with COPD1 and is higher than that which we found in healthy subjects (12%).1

On the other hand, the prevalence of OSA in patients with COPD has been estimated at 10%, which is similar to that found in an equivalent general population4 and considerably less than the frequency of MCI observed in our study.1 OSA is usually diagnosed based on polysomnographic recording and the presence of excessive daytime sleepiness. In our study, polysomnographic recording was not available to control for OSA. However, based on the Epworth Sleepiness Scale (ESS), patients with COPD did not differ from control subjects in the severity of daytime sleepiness symptoms (P = .45).1 Although patients with COPD and MCI had a slightly higher ESS total score (8.42) compared with patients with COPD without MCI (6.28), the difference did not reach significance (P = .62).1 Furthermore, no significant difference was found in the proportion of subjects with excessive daytime sleepiness (ESS ≥10) between patients with COPD and control subjects (20% vs 18%; χ2 test =0.02; P = .90) or between patients with COPD with and without MCI (29% vs 15%; Fischer exact test, P = .41). Therefore, although we could not determine the proportion of subjects with objectively confirmed OSA in our sample, our results on the ESS suggest that daytime sleepiness, which is a central symptom in OSA diagnosis, is probably not a major factor explaining the high frequency of MCI in the COPD cohort.

Nevertheless, as mentioned by Dr Damiani and colleagues, the coexistence of OSA and COPD (overlap syndrome)4,5 may cause more severe cognitive impairment, increasing the risk of cognitive decline in this subgroup of patients. This would have important implications for the clinical support and follow-up of patients with COPD. Thus, further longitudinal studies in larger samples are needed to better assess the impact of OSA on cognition in COPD.

References

Villeneuve S, Pepin V, Rahayel S, et al. Mild cognitive impairment in moderate to severe COPD: a preliminary study. Chest. 2012;142(6):1516-1523. [CrossRef] [PubMed]
 
Yaffe K, Laffan AM, Harrison SL, et al. Sleep-disordered breathing, hypoxia, and risk of mild cognitive impairment and dementia in older women. JAMA. 2011;306(6):613-619. [CrossRef] [PubMed]
 
Gagnon K, Gosselin N, Mathieu A, et al. Mild cognitive impairment in obstructive sleep apnea: a pilot study [abstract]. Sleep. 2012;35(suppl):A186.
 
McNicholas WT. Chronic obstructive pulmonary disease and obstructive sleep apnea: overlaps in pathophysiology, systemic inflammation, and cardiovascular disease. Am J Respir Crit Care Med. 2009;180(8):692-700. [CrossRef] [PubMed]
 
Hung WW, Wisnivesky JP, Siu AL, Ross JS. Cognitive decline among patients with chronic obstructive pulmonary disease. Am J Respir Crit Care Med. 2009;180(2):134-137. [CrossRef] [PubMed]
 

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Tables

References

Villeneuve S, Pepin V, Rahayel S, et al. Mild cognitive impairment in moderate to severe COPD: a preliminary study. Chest. 2012;142(6):1516-1523. [CrossRef] [PubMed]
 
Yaffe K, Laffan AM, Harrison SL, et al. Sleep-disordered breathing, hypoxia, and risk of mild cognitive impairment and dementia in older women. JAMA. 2011;306(6):613-619. [CrossRef] [PubMed]
 
Gagnon K, Gosselin N, Mathieu A, et al. Mild cognitive impairment in obstructive sleep apnea: a pilot study [abstract]. Sleep. 2012;35(suppl):A186.
 
McNicholas WT. Chronic obstructive pulmonary disease and obstructive sleep apnea: overlaps in pathophysiology, systemic inflammation, and cardiovascular disease. Am J Respir Crit Care Med. 2009;180(8):692-700. [CrossRef] [PubMed]
 
Hung WW, Wisnivesky JP, Siu AL, Ross JS. Cognitive decline among patients with chronic obstructive pulmonary disease. Am J Respir Crit Care Med. 2009;180(2):134-137. [CrossRef] [PubMed]
 
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