Abstract
BackgroundChronic Obstructive Pulmonary Disease (COPD) is a progressive respiratory condition which can lead to comorbidities of variable severity, cognitive dysfunction included. The role of supplemental oxygen in preventing COPD-induced cognitive deterioration is still debated, but only episodically investigated. The aim of this study was to compare the cognitive pattern of hypoxemic COPD subjects treated with long-term oxygen (LTOT) to that of patients of comparable severity assuming oxygen on irregular basis, and to normal reference values.MethodsLung function, arterial blood gases, health status, and cognitive function measured by means of four psychometric tests focusing different domains of cognition (such as: MMSE, Clock test; TMT-A; TMT-B) were assessed in 146 well matched hypoxemic COPD patients (males n = 96, 66%; mean age = 70.5 ± 12.9). Seventy-three patients were assuming long-term oxygen (LTOT), while the remaining seventy-three were only using oxygen as needed (AN). Regarding statistics, t test and ANOVA (Duncan test) were used to analyze data, assuming a p < 0.05 as the lowest limit of significance.ResultsEven though all COPD patients showed a poorer psychometric profile vs corresponding normal reference values, LTOT patients showed a lower prevalence of severe deterioration in cognition. Also the extent of impairment was significantly lower in these patients when assessed by TMT-A and TMT-B (p < 0.012 and 0.001, respectively), but not when measured by MMSE and Clock test (both p = ns). Several domains of cognition are variably affected by persistent hypoxemia in COPD patients. A panel of psychometric tools is needed for identifying the pattern of cognitive dysfunctions in these patients. Memory and attention (functions assessed by MMSE and Clock test) are only mildly-moderately affected, while visual processing, reproduction of numeric sequences, cognition flexibility, and shifting capacity (functions assessed by TMT-A and TMT-B) are much more deteriorated (p < 0.012 and p < 0.001, respectively).ConclusionsOnly LTOT allows to preserve significantly (p < 0.022) cognitive functions from the COPD-induced deterioration. This assumption is of strategic value for COPD patients who are prescribed long-term oxygen because they frequently are not aware of the cognitive risks related to their condition.
Highlights
Chronic Obstructive Pulmonary Disease (COPD) is a progressive respiratory condition which can lead to comorbidities of variable severity, cognitive dysfunction included
It has been demonstrated that hypoxemia per se can play a role in affecting cognition [21], and it might contribute to the onset and the progressive worsening of cognitive functions in subjects suffering from COPD, in most severe cases [22]
A specific study focused on these aspects and confirmed that both the prevalence and the extent of cognitive deterioration occurring in subjects with stable COPD of different severity are directly related to the severity of their pulmonary condition, hypoxemia included
Summary
Chronic Obstructive Pulmonary Disease (COPD) is a progressive respiratory condition which can lead to comorbidities of variable severity, cognitive dysfunction included. Impairment of cognitive functions is one of the effects of comorbidities related to COPD [6,7,8,9] It has long been associated with severe pulmonary dysfunction [10,11,12,13,14,15], even if at a changing prevalence in different studies, because depending on the methods for assessing cognition and on the consistency of subjects’ sample [16,17,18,19,20]. Neverheless, other authors support the hypothesis that cognitive function is only mildly impaired without hypoxemia, and that cognitive dysfunction is higher in hypoxemic patients [9]
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