Obstructive Sleep Apnea Plays Cognitive Impairment Role in IPF Patients, Study Suggests
Patients with idiopathic pulmonary fibrosis (IPF) have, on average, only slight cognitive impairment compared to healthy people. Also, IPF patients with severe obstructive sleep apnea have worse cognitive impairment.
The study with those findings, “Impact of moderate to severe obstructive sleep apnea on the cognition in idiopathic pulmonary fibrosis,” was published recently in the journal PLOS ONE.
Patients with IPF, a progressive lung disease, generally have multiple comorbidities, with the most common ones being respiratory problems, such as emphysema, lung cancer, and pulmonary hypertension.
Another common comorbidity is obstructive sleep apnea (OSA), which is estimated to be present in 58-88 percent of IPF patients. OSA is a potentially serious sleep disorder that causes breathing to repeatedly stop and start during sleep, leading to low levels of oxygen in the blood (hypoxemia) for a long period of time.
Hypoxemia is a potential risk factor for the development of cognitive impairment.
There is a lack of studies investigating cognitive impairment in IPF patients, and the few studies that delved into this topic show that almost half of patients demonstrate at least mild cognitive dysfunction, and that such cognitive impairment correlates with IPF severity.
Cognitive impairment in patients with OSA is a well-documented phenomenon. However, it is unknown how OSA in IPF patients contributes to cognitive issues in this patient population.
So, researchers at “Victor Babes” University of Medicine and Pharmacy, in Romania, conducted a study to assess cognition in IPF patients, and to identify factors that might play a role in cognition.
The team evaluated 23 IPF patients and used the Montreal Cognitive Assessment (MoCA), an instrument for detecting mild cognitive impairment. “MoCA evaluates several cognitive domains (short-term memory, visuospatial abilities, executive functioning, attention, concentration and working memory, language, orientation in time and space),” the researchers wrote.
Cognitive impairment, according to the MoCA, is set by a score of 23 or less.
Patients also were screened for OSA through an overnight cardiorespiratory polygraphy, and for anxiety and depression using the Generalized Anxiety Disorder 7-item (GAD-7) scale, the Patient Health Questionnaire (PHQ-9), and the Hospital Anxiety and Depression Scale (HADS).
Results indicated that IPF patients had a slight cognitive impairment compared to healthy participants used as controls, as demonstrated by an average MoCA score of 24 for IPF patients, and 27 for healthy subjects. The MoCA domains that were found to be significantly impaired in IPF patients were visuospatial abilities, language, and working memory.
In the group analyzed, OSA was diagnosed in 19 (82.6%) IPF patients; 12 of those patients (63.15%) had a moderate-to-severe form of OSA.
A correlation analysis showed that IPF patients with cognitive impairment exhibited a higher severity of OSA, and a higher Epworth score (a subjective measure of a patient’s sleepiness).
Anxiety and depression scores were found not to be correlated with MoCA results.
Based on the results, researchers concluded that “impaired cognition in patients with IPF is mild, and affect the areas of visuospatial abilities, language, and working memory.”
“OSA could be a possible predictor of IPF cognition deficit,” the researchers added, suggesting that “given the high prevalence of multiple types of sleep disorders in IPF patients, these should be investigated at least by cardiorespiratory polygraphy.”