How Lung Function May Drive Brain Fog in Long COVID

Emerging research presented at the Radiological Society of North America's (RSNA) annual meeting sheds new light on one of long COVID's most challenging symptoms—cognitive dysfunction, often referred to as "brain fog." Researchers from the University of Iowa have identified a potential connection between impaired pulmonary gas exchange and cognitive difficulties in long COVID patients. This groundbreaking study, which employed advanced imaging techniques, provides fresh insight into how lung and brain function may interact in individuals suffering from prolonged symptoms after COVID-19 infection.

A Novel Multiorgan Imaging Approach

The study is the first to jointly examine lung and brain function using magnetic resonance imaging (MRI) in long COVID patients. Researchers utilized hyperpolarized xenon-129 (¹²⁹Xe) pulmonary MRI to assess gas exchange—how oxygen moves from the lungs to the bloodstream and carbon dioxide is expelled—and combined this data with structural and functional brain MRI scans. The analysis also included pulmonary function tests and cognitive assessments.

"This research is new in that it combines multiple unique imaging types to study a multiorgan relationship in a disease population," explained lead author Keegan Staab, B.S., a graduate research assistant at the University of Iowa. Among the key findings, patients with lower pulmonary gas exchange were observed to have reduced gray and white matter volumes and reported significant cognitive difficulties. Additionally, an association between decreased gas exchange and increased cerebral blood flow was noted, suggesting a possible compensatory mechanism.

Why These Findings Matter

Long COVID affects an estimated 17.6% of adults in the United States, with symptoms ranging from fatigue and dyspnea to cognitive dysfunction. Understanding the interplay between lung and brain function in these patients is critical for developing targeted treatments. Senior study author Sean B. Fain, Ph.D., noted that if the findings are generalized, they could pave the way for interventions aimed at improving pulmonary gas exchange to alleviate cognitive symptoms.

The study's results also raise important questions about underlying mechanisms, including whether vascular injury caused by COVID-19 could simultaneously impair lung and brain function. Researchers emphasize the need for larger studies to confirm the findings and explore their implications further.

"This relationship could be a compensatory mechanism where lower lung function is compensated by higher cardiac output and higher brain perfusion," Staab added. "It's also a possibility that the disease mechanism that impairs pulmonary gas exchange also leads to higher brain perfusion through downstream vascular injury in both lung and brain." 

Toward Improved Diagnosis and Care

The researchers suggest that abnormalities in pulmonary gas exchange may serve as a biomarker to identify long COVID patients at higher risk of cognitive impairment. Such insights could inform personalized treatment plans and long-term management strategies, particularly for patients with persistent dyspnea or fatigue.

With the potential to advance understanding of multiorgan impacts in long COVID, this research underscores the importance of interdisciplinary approaches in addressing the complex challenges posed by the condition.