October 24, 20237:28 AM ET
By Will Stone
Scientists have uncovered a possible explanation for one of COVID-19's most vexing legacies: the stubborn neurological symptoms of long COVID, such as brain fog, memory loss and fatigue.
The first clue emerged when researchers scoured the blood of long COVID patients: It was serotonin – specifically, a lack of the neurotransmitter circulating in the body — that grabbed their attention.
Their analysis revealed that having low levels of that chemical predicted whether or not someone was suffering from persistent symptoms following an infection.
Next, the team of researchers at the University of Pennsylvania carefully recreated the chain of events that might be depleting serotonin and causing downstream consequences that could line up with some of the symptoms characteristic of long COVID.