While past studies have found that women are more frequently affected by long COVID than men, the new study published today in the Annals of Clinical and Translational Neurology showed for the first time that women report more neurologic symptoms of long COVID and experience worse impacts on quality of life and cognitive function than men. 

“We were surprised to see such a significant difference between female and male patients,” said Igor Koralnik, MD, chief of neuroinfectious disease and global neurology at Northwestern Medicine. “Both in the frequency of neurologic long COVID symptoms and in levels of self-reported fatigue, as well as in a cognitive task of attention.”

Study highlights

• The study looked at the first consecutive 2,329 patients who have been seen at the Northwestern Medicine Neuro COVID-19 Clinic.
• Approximately 2/3 of patients were women.
• Women more frequently reported neurologic symptoms such as brain fog, dizziness, headache, numbness and tingling and pain.
• No neurologic symptoms were more common in men.
• Women also reported more non-neurologic symptoms, such as fatigue, shortness of breath, chest pain, dysautonomia and gastrointestinal issues.
• Women also reported worse alteration of their quality of life caused by fatigue than men on standardized questionnaires.
• Women scored lower than men in a task of attention on objective cognitive tests.

“We think that the reason women are more frequently and severely affected by long COVID than men is because long COVID is an autoimmune disease, and women are more prone to autoimmune diseases than men, including multiple sclerosis and rheumatoid arthritis,” Dr. Koralnik said. “We and others have found evidence of immune dysregulation and autoimmunity in patients with long COVID. We next want to understand the underlying causes for the neurologic symptoms of long COVID and identify and validate biological markers that show how active the disease is. We hope our study will alert providers about the importance of timely diagnosis and targeted interventions in female patients, who are often negatively affected by gender bias in medicine.

“A Household Pulse Survey conducted by the National Center for Health Statistics estimated that nearly 18 percent of U.S. adults had experienced long COVID and that five percent were experiencing it as of September 2024. It is safe to estimate that long COVID still affects millions of adults in the United States currently,” said Dr. Koralnik. 

To date, the Neuro COVID-19 Clinic has treated more than 3,300 patients with long COVID from 44 states. While severe cases of COVID-19 requiring hospitalization have become rare, Dr. Koralnik says COVID-19 continues to occur and the risk of developing long COVID increases with repeat occurrences of COVID-19.

Northwestern Memorial Hospital is ranked No. 6 in the nation for neurology and neurosurgery by U.S. News & World Report, 2025-2026. For more information, visit nm.org and to schedule an appointment with the Neuro COVID-19 Clinic, call 312.695.7950.

CHICAGO – February 18, 2025 – How much can the eyes reveal about a person? A first-of-its-kind study from Northwestern Medicine and published in the Journal of Imaging is giving experts an idea how long COVID affects the body by looking through the eyes. The research could help doctors diagnose and track how the condition impacts people over time and provide insight into the cause of long COVID.

In the study, researchers used advanced imaging techniques to examine the retinas of non-hospitalized long COVID patients from the Northwestern Medicine Neuro COVID-19 Clinic and found that patients with long COVID experienced a significant reduction in the density of blood vessels in the back of the eye, compared to healthy individuals.

“This finding bridges gaps between ophthalmology, neurology, and COVID-19, helping us better understand how inflammation affects different organs in the body,” said Manjot K. Gill, MD, senior author of the study and ophthalmology lead of the Northwestern Medicine Comprehensive COVID-19 Center. “The change in blood vessels in the deep part of the retina supports the hypothesis that long COVID affects similar blood vessels in other parts of the body, like the brain, which can potentially contribute to the symptoms of long COVID such as memory loss, brain fog and fatigue.”

In patients with long COVID, researchers found that the most significant change was a decrease in blood flow in the smallest blood vessels in the deeper layers of the retina. Researchers believe this decrease in circulation may be reflective of decreased blood circulation in the brain, which may lead to neurologic symptoms.

“In oculomics – the field of study that examines the relationship between eye health and systemic diseases – we are understanding the power of the retina as a biomarker for disease, identifying early signs of diabetes, cardiovascular disease, and neurodegenerative disorders. It’s exciting to see how long COVID could fit into this framework,” said Dr. Gill. “Retinal imaging allows us to see the blood vessels that we cannot readily image elsewhere, so in this context, the eyes really are the ‘window to the soul.’”

Building on these findings, researchers are launching a longitudinal study that will examine how the changes in the deep retinal blood vessels relate to patient symptoms and other established markers of long COVID. They hope to determine if retinal imaging could be used as a tool to diagnose, manage and predict the progression of long COVID over time, as well as identify its cause.  

“Even though the immediate threat of the COVID-19 pandemic has decreased, approximately one-third of COVID-19 survivors experience lingering effects. This issue affects an estimated 17 million adults in the U.S. and comes with significant healthcare and economic burdens, costing about $600 million in lost wages,” said Igor Koralnik, MD, chief of neuroinfectious diseases and global neurology at Northwestern Medicine, who oversees the Neuro COVID-19 Clinic and is the co-director of the Northwestern Medicine Comprehensive COVID-19 Center. “There are currently no specific treatments for long COVID, and this research helps to advance our understanding of the condition. By studying the effects of COVID-19 on the body, we can improve diagnosis, management, and support for those affected.”

To date, the Neuro COVID-19 Clinic has cared for nearly 3,000 long-haulers from 44 states. For more information, visit nm.org and to schedule an appointment, please call 312.695.7950.