"TBI can be attenuated by vitamin B-12 treatment through its beneficial role on axon regeneration after nerve injury."

broad-spectrum antiviral (ribavirin), anti-hepatitis B virus (telbivudine), two vitamins (vitamin B12 and nicotinamide{B3})

— Bean Davidson *advanced B12 and cofactors please* (@bean_b12) September 9, 2022

Okay, so this should be of help to those trying to fix this and that.  I'm not familiar with those two drugs--Ribavirin and Telbivudine--but I am familiar with B12 and B3, Niacin.  Niacin has already been proven to be an effective anti-COVID symptom therapy.  It is often referred in the literature to a clot buster.  In addition, it keeps any of the spike proteins from adhering to tissue.  So if you've taken the vaccine, this is one function that you'll want to avail yourself of.  The other compound, B-12, is almost exclusively an excellent nerve tonic and nerve regenerator.  Yep, a nerve regenerator.  In this era of COVID, we hear a lot about muscle wasting and shrinkage, like brain shrinkage.  Well, B12 maintains brain volume if you take it regularly.  One of the benefits of eating nutrient dense animal protein is that you're getting adequate B-12.  NCBI reports that 

Vitamin B12 has been reported to promote axon growth of neuronal cells after peripheral nerve injury, which is currently used for the treatment of peripheral nerve damage in the clinical trial. Thus, we hypothesized that TBI can be attenuated by vitamin B-12 treatment through its beneficial role on axon regeneration after nerve injury. 

So if you're looking for a compound to regrow nerve tissue, look no further than B12.  

METHYLCOBALAMIN, B-12, SLOWS BRAIN SHRINKAGE & RESTORES YOUR CIRCADIAN RHYTHMS

George Hoyt Whipple discovered B-12 in 1934.  So knowledge of this nutritional compound is well known and well-studied.  B-12 is water soluble, plays a key role in the normal functioning of the brain and nervous system, and basically interacts with the bacteria in your body to produce energy, described here:

Vitamin B₁₂, also called cobalamin, is a water-soluble vitamin that has a key role in the normal functioning of the brain and nervous system via the synthesis of myelin (myelinogenesis),^[1][2] and the formation of red blood cells. It is one of eight B vitamins. It is involved in the metabolism of every cell of the human body, especially affecting DNA synthesis, fatty acid and amino acidmetabolism.^[3] No fungi, plants, or animals (including humans) are capable of producing vitamin B₁₂. Only bacteria and archaea have the enzymes needed for its synthesis. Some substantial sources of B₁₂ include animal products (shellfish, meat), fortified foods, and dietary supplements.^[4][5] B₁₂ is the largest and most structurally complicated vitamin and is produced industrially only through bacterial fermentation. This B₁₂ is used for fortified foods and supplements. It has also been produced synthetically via vitamin B₁₂total synthesis.

Yeah, the synthetic version of B-12, called cyanocobalamin, actually has cyanide in it.  You may want to steer clear of that one.  Methylcobabalmin is the preferred for of B-12.

Sardi published an article back on September 11, 2013, titled "The Incredible Shrinking (Mushy) Vitamin B-12 Deficient Brain."  It will alert you to the serious problems that result from a B-12 deficiency, and I say this as a guy who takes a supplement daily (with a B-12 dose of 320mcg; that exceeds a maintenance dose by 5000%.  I wonder what a therapeutic dose is).  His article starts with a citation to the Tufts University study on how a mild deficiency of B-12 speeds dementia.  Yikes.  In terms of numbers, what is a deficiency of B-12?  

Magnetic resonance imaging (MRI) scans of the brain of a 76-year-old patient with dementia. The brain has shrunk, and the ventricles, the fluid-filled spaces (dark brown) at the center of the brain, have become enlarged. Photo: BSIP/Photoresearchers Inc.

It's elusive.  According to the B-12 website (yes, there's a website dedicated just to vitamin B-12), he states that it is 7ug, whatever that is.  But there is a summary to the article, and that's here:

The daily requirement according to DGE: 3 µg.  

The daily requirement is not actually the necessary amount!

Current studies recommend an intake of 7-10 µg.
During stress, illness and pregnancy, a higher intake is required.
Vegans should take supplements. 

Okay, so it looks like you want to be maintaining, meaning taking on a daily basis, 3 µg.  So anything less than that, you risk becoming deficient and moving toward mild dementia.  So don't start down that road.  It's a lot easier to remember to take the methylcobalamin, B-12, than to try to rebuild the brain.  

Investigators at Tufts University display striking images of the human brain when it is deficient in vitamin B-12.  Brain scans show fluid-filled spaces as the center of a shrinking B-12 deficient brain—literally holes in the brain. 

The report starts

Being even mildly deficient in vitamin B-12 may put older adults at a greater risk for accelerated cognitive decline, an observational study from the Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts suggests.  

Still, no numbers on how to measure "Being even mildly deficient . . . ."  

BENEFITS OF B-12, METHYLCOBALAMIN

BENEFIT #1:  Delays and significantly slows the shrinkage of the brain.  Methylcobalamin, B-12 produces stunning benefits on the brain, on the heart, on the spine, and the muscles and nerves that run all through your body.  It slows brain shrinkage by 7 times of what is normal.  This should be a daily regimen for life.   

A prior study showed that high-dose B vitamins (800 mcg folic acid, 20mgs vitamin B6, 500 mcgs of B-12) slows the rate of shrinkage in the human brain, and more demonstrably (by 7 times) shrinkage of grey matter in the brain.

So here I've listed some of the benefits of B-12: Methyllcobalamin, B-12, Betaine Hydrochloride, and Benfotiamine.  But what causes brain shrinkage in the first place?  Is there a way to prevent shrinkage or avoid it altogether?  First, I would stay away from foods drain the B-12 stores from your body, things like coffee, alcohol, digestive disorders, pernicious anemia, injuries, and worst of all, stress.  Stress is a killer, especially chronic stress.  B-12 helps fight off the damaging effects of stress on the brain.  

BENEFIT #2:  B-12 revitalizes and restores brain, heart, and spinal energy.  Few things do all three.

BENEFIT #3:  B-12 restores your circadian rhythms.  You will get the best sleep of your life.  Nothing compares.  Plus, given all the other benefits of how it rebuilds the brain, spine, heart, blood vessels, tell me, what's not to like.  If your sleep is better, just think how less irritable you'll be the next day.  I got the best sleep I'd head in decades.   

Effects of vitamin B12 on performance and circadian rhythm in normal subjects.  Neuropsychopharmacology, 1996.

This preliminary study investigates effects of methyl- and cyanocobalamin on circadian rhythms, well-being, alertness, and concentration in healthy subjects. Six women (mean age 35 years) and 14 men (mean age 37 years) were randomly assigned to treatment for 14 days with 3 mg cyano-(CB12) or methylcobalamin (MB12) after 9 days of pre-treatment observation. Levels in the CB12 group increased rapidly in the first, then slowly in the second treatment week, whereas increase in the MB12 group was linear. Urinary aMT6s excretion was reduced by both forms of vitamin B12 over 24 hours with a significant decrease between 0700-1100 hours, whereas urinary excretion of potassium was significantly increased between 0700-1100 hours. Activity from 2300-0700 hours increased significantly under both forms of vitamin B12. Sleep time was significantly reduced under MB12 intake. In this group the change in the visual analogue scales items "sleep quality," "concentration," and "feeling refreshed" between pretreatment and the first week of treatment showed significant correlations with vitamin B12 plasma levels. Cortisol excretion and temperature were not affected by either medication. We conclude that vitamin B12 exerts a direct influence on melatonin. Only MB12 has a positive psychotropic alerting effect with a distribution of the sleep-wake cycle toward sleep reduction.

WHAT B12 DEFICIENCY LOOKS LIKE

You already know what it looks like: fatigue because your circadian rhythms are ruined; poor appetite because you're eating fast food and coffee because you're trying to compensate for the deleterious disruption of your circadian rhythms.  Get the B-12.  Depression and numbness and tingling in the hands and or feet all for the same reason: disruption of your circadian rhythms that are built on your body's ability to coordinate its nerve and muscle and hormone functions properly.  You don't want to let these conditions go unanswered.  Get the B-12.  Take it throughout the day.  Take it daily.  It's at this point that most medical articles will say "so speak to your doctor promptly about treatment," but I would say, hey, your doctor doesn't know much about nutrition and even less about nutritional supplements, so instead of speaking with your doctor, consult the valuable articles and books by Bill Sardi.  

CAUSES OF B-12 DEFICIENCY
Bill Sardi points to two causes of B-12 deficiency: lack of absorption and H. Pylori bacterium.  The latter shuts down stomach acid and the former   

Lack of absorption of dietary and supplemental vitamin B-12 due to progressive inability to produce stomach acid is cited as a growing concern.  Therefore, it may be that widespread H. Pylori infection, which is prevalents in more than half of the US population, could be a parallel facto as H. Pylori shuts down production of stomach acid or hydrochloric acid. 

Lack of absorption is a serious problem for oldsters.  We might eat right but we're just not absorbing the nutrition that we need from a healthy diet.  

The academy estimates that between 10 percent and 30 percent of people older than 50 produce too little stomach acid to release B12 from its carrier protein in foods, and as the years advance, the percentage of low-acid producers rises.

Diabetics are at an added risk.

Another concern is that most often used anti-diabetic drug, metformin, depletes the body of vitamin B-12.  Metformin use has been associated with decliningmental function.

REMEDY THE DEFICIENCY

1.  Eat lean animal meats to get B-12 from food. 

Animal proteins, such as lean meats, poultry and eggs, are good sources of vitamin B-12. Because older adults may have a hard time absorbing vitamin B-12 from food, the USDAʼs 2010 Dietary Guidelines for Americans recommend that people over age 50 incorporate foods fortified with B-12 or supplements in their diets.

2.  Supplement with Betaine Hydrochloride to replenish stomach acid so that you can digest the foods above and get the needed B-12.  

The group studied did eat meats, so one of the reasons for them being deficient is due to low stomach acid at age 75 and above.  To remedy the problem of low stomach acid, then you'll need to supplement with Betaine Hydrochloride.  For low stomach acid, Sardi recommends the following:  

1) Follow an anti-H Pylori regimen;

2) Supplement your diet with zinc which is needed to make hydrochloric acid in the stomach. [I never heard of this before];

3) Take Betaine Hydrochloride with meals to provide supplemental acid source. 

SUPPLEMENTS TO REMEDY NERVE & MUSCLE FATIGUE, A TIRED HEART, A TIRED BRAIN, AND A TIRED SPINE

Methylcobalamin
 

If you're not getting enough B12 from the meats and eggs in your diet, supplement with this hydrochloric acid to help break down those proteins and other nutrients, like B-12

Betaine Hydrochloride.  


Mind Boosters: A Guide to Natural Supplements That Enhance Your Mind, Memory, and Mood, Ray Sahelian, 2000.