Tulane Study Uncovers Unique Neural Pathologies of COVID-19: Disrupted Serotonin and Dopamine Signaling Drive ‘Brain Fog’

Tulane researchers find COVID-19 disrupts serotonin and dopamine in the brain, unlike the flu. Explore the biological causes of Long COVID neurological symptoms.

By: AXL Media

Published: Feb 26, 2026, 7:09 AM EST

Source: The information in this article was sourced from Tulane University

Distinguishing the Long-Term Echoes of Respiratory Infection

While the immediate symptoms of COVID-19 and the flu often overlap, their long-term trajectories in the human body are fundamentally different. New research from the Tulane National Primate Research Center has identified the specific biological markers that separate "Long COVID" from standard post-viral fatigue. By utilizing a mouse model to analyze tissues weeks after the viruses were cleared, scientists discovered that SARS-CoV-2 leaves a unique "neurological footprint" that is absent in influenza cases. These findings provide a vital foundation for understanding why millions of patients report cognitive impairment, mood shifts, and persistent fatigue following even mild COVID-19 infections.

Lung Damage: A Shared Legacy of Scarring

In the respiratory system, both COVID-19 and the flu exhibited strikingly similar long-term effects. Both viruses caused the immune system to remain in a state of high alert, leading to an overproduction of collagen—a protein that causes tissue scarring and stiffness. This physiological change explains why survivors of both infections frequently report lingering shortness of breath. However, a critical distinction emerged during the repair phase: while flu-infected lungs transitioned into an active rebuilding mode to repair airway linings, COVID-19 lungs showed a marked absence of this healing response, suggesting the virus may permanently inhibit the body's natural respiratory recovery mechanisms.

The COVID-Specific Impact on Neurotransmitters

The most significant discovery of the Tulane study centered on the brain's internal signaling environment. Even though the virus itself was not detected in brain tissue, COVID-19 survivors showed chronic brain inflammation and micro-hemorrhages (tiny areas of bleeding). Most notably, gene expression analysis revealed a severe disruption in the pathways regulating serotonin and dopamine—the "reward and mood" chemicals. These systems are essential for cognition, energy, and emotional regulation. This disruption serves as a definitive biological smoking gun for "brain fog," suggesting that the neurological symptoms of Long COVID are driven by systemic neuro-inflammation rather than direct viral infection of the brain.