Hi- I saw this post and was wondering about the same thing. I found this, which I think may answer some of the questions. I’m really intrigued.
https://medicine.yale.edu/news-article/potential-new-treatment-for-brain-fog-in-long-covid-patients/#:~:text=Patients%20also%20took%20600%20mg,to%20resume%20their%20normal%20activities
I won’t take a stab at trying to explain the science behind the suspected mechanism of action lol, maybe better to hear it from the researchers themselves.

The study they reference can be found here: https://www.sciencedirect.com/science/article/pii/S2667257X22001000

From what I gather, NAC is an anti-inflammatory (the dose was 600 mg daily in a separate supplement). And the Guanfacine is an ADHD medication, but has been used successfully off label to improve cognitive function in TBI (the dose they reported using was 1 mg nightly, increased to 2 mg if the person tolerated it well—it seems that is the standard dose for either ADHD or TBI).

The sample size on their study is very small, but considering NAC is relatively safe and the guanfacine is also a known medication that in theory a PCP might even feel comfortable prescribing if it’s used for ADHD, that also has evidence behind it being used for TBI…it seems relatively low risk to try?

I don’t take either, but my PCP had brought up NAC.

I do take LDN; those dosing regimens are easy to find online. The typical dose is 4.5 mg with a slow titration that seems to depend on what the doctor/patient decide is best. I started at a quarter mg and worked my way up to that. Some people start higher (and it is also very low risk of side effects).