Fascinating study examines role of herpesviruses in Long COVID brain fog - and a dementia drug may help!
This new study from Tokyo Jikei University School of Medicine shines a pretty powerful light on a potential cause of Long COVID brain fog, at least in a subset of patients.
Their work built on previous studies that showed Long COVID patients had high levels of anti-SITH-1 antibodies, an indicator of HHV-6B reactivation in the body.
In lab experiments with mice, they then induced expression of the SITH-1 protein in the olfactory bulb, a part of the brain which SARS-CoV-2 is known to infect.
The animals then experienced reduced levels of acetylcholine, leading to behavior that mimicked resembling fatigue and depression.
When the mice were given donepezil, a dementia medication that increases acetylcholine levels, their symptoms improved.
They then examined the results of a previous human trial of donepezil (not specific for Long COVID). It turned out that the subjects who tested positive for anti-SITH-1 antibodies experienced significantly improved measures of fatigue and depression.
The article quotes research team lead Naomi Oka, lecturer in virology at the Jikei University School of Medicine. She explains,
>"While there are currently no effective treatments for long COVID, our findings suggest that the dementia medication donepezil may help improve fatigue and depression. Development is also underway for a diagnostic method that would identify suitable patients with anti-SITH-1 antibodies." She added, "The findings suggest a link to brain inflammation caused by acetylcholine deficiency, and the same mechanism may potentially be applicable to other disorders, including depression."
This is fairly optimistic news! Development is already underway for a diagnostic method to detect anti-SITH-1 antibodies, meaning we are well on our way toward having a biomarker!
It is true that to target the real root cause would mean having a treatment for the viral reactivation. Yet this is still a great and important start, and having a strong treatment to mitigate the symptoms would do a lot to help Long COVID patients in the meantime.
New research is coming out every day - hang in there, everyone!