Methylene Blue Dosing Suggestions:
 
Use Methylene Blue Pharmaceutical USP (United States Pharmacopeia) grade  99%+ pure. This is the kind used when injected intravenously for antidote purposes, or used orally. 
"For an acute treatment, the upper limit is between 3 mg to 4 mg per kg, which is
typically the range given as an IV antidote for methemoglobinemia. For nonacute,
more long-term treatment, 0.5 mg to 1 mg per kg per day works better."[REF].
Oral intake is the simplest way to take it, given its high bioavailability (almost 100%). 
Prepare a water diluted mixture (you may want to watch this video) and take it in the morning before any meal.
Two important notifications: 
1. Administrating methylene blue, gives the urine and feces the blue color!
2. The half-life of oral methylene blue is 4 to 6 hours (It is important to consider the half-life issue here when there are missed doses or when increasing the dose to twice or three times daily). 
Let’s take the example of a 100 mg oral methylene blue dose with a half-life of 6 hours:
Imagine you take your dose at 8 am…
half-life #1: 50 mg left in your body at 2 pm (i.e., 6 hours later) 
half-life #2: 25 mg left in your body at 8 pm (i.e., another 6 hours later)
half-life #3: 12.5 mg left in your body at 2 am
half-life #4: 6.25 mg left in your body at 8 am
This means that if you take 100 mg of methylene blue at 8 am, you'll still have 6.25 mg of methylene blue in your body 24 hours later. 
Even if we assume that the methylene blue half-life is 4 hours, then there would be 3.125 mg of methylene blue left in your body at 8 am the next day.
Either way, 100 mg daily methylene blue taken daily will continue to build up in your system, and this buildup could lead to adverse effects, especially when the accumulative dose reaches 3 mg/kg or greater. 

Gut Microbiome And Our Brain [Read more]
The guts and its microbiome - referred to by many as our second brain. 
This scientific study - (as an example) has found that probiotic and prebiotics might improve mental function via several mechanisms. (Read more) Another scientific study has found two strains - Lactobacillus helveticus and Bifdobacterium longum, that have shown to have a calming influence, in part by dampening stress hormones. Other strains may have similar effects, although more research is needed to identify them. Using MRI scans, Dr. Emeran Mayer, a professor of medicine and psychiatry at the University of California, studied the physical brain structure of thousands of volunteers, looking for connections between brain structure and the types of bacteria found in their guts. So far, he has found differences in how certain brain regions are connected, depending on the dominant species of bacteria. As reported by NPR: "That suggests that the specific mix of microbes in our guts might help determine what kinds of brains we have — how our brain circuits develop and how they're wired." (Read more). Indeed, the connection between our gut and mental health appears to be so strong that some have proposed probiotics may one day take the place of antidepressant drugs.

The accumulating evidence linking bacteria in the gut and neurons in the brain (the microbiota–gut–brain axis) has led to a paradigm shift in the neurosciences. Understanding the neurobiological mechanisms supporting the relevance of actions mediated by the gut microbiota for brain physiology and neuronal functioning is a key research area.

Gut bacteria transmits information to your brain via the vagus nerve, the tenth cranial nerve that runs from your brain stem into your enteric nervous system (the nervous system of your gastrointestinal tract). There is a close connection between abnormal gut flora and abnormal brain development, and just as you have neurons in your brain, you also have neurons in your gut - including neurons that produce neurotransmitters like serotonin, which is also found in your brain and is linked to mood.

Cognitive Functioning Nutritional Supplements:

Lion's Mane Mushrooms
 
We recommend this supplement following unequivocal recommendations of figures whom we learned to appreciate their integrity and professionalism over a prolonged period of time like Mike Adams in this video (on min. 17:00) and Dr. Gundry in this video (on min. 1:28) and a few other of his videos. Their recommendations and some preliminary studies like this one that concludes "Given the current evidence, lion’s mane mushrooms may have the potential to elicit both cognitive and mood effects through various biological pathways", let us to strongly recommend this supplement.
Dosage: In this study the dosage of the powder in a pill form used was 3 grams and generally speaking, this dosage is recommended by many other studies and videos.
 
Spirulina: "This review focuses on the role of Spirulina in the brain, highlighting how it exerts its beneficial anti-inflammatory and antioxidant effects, acting on glial cell activation, and in the prevention and/or progression of neurodegenerative diseases, in particular Parkinson’s disease, Alzheimer’s disease and Multiple Sclerosis; due to these properties, Spirulina could be considered a potential natural drug". The above is the conclusion of one study out of numerous recent studies, all showing the benefits of spirulina to cognitive functioning.
Dosage: As a dietary supplement, the recommended minimum amount is three grams daily – one teaspoon of powder or six 500 mg tablets. Since it is a pure and natural food, you may safely take more, to suit your personal health program.

Vitamin B12: vitamins including vitamin B12 may slow brain shrinkage by as much as seven-fold in brain regions specifically known to be most impacted by Alzheimer's disease. (
The researchers noted: "…B vitamins lower homocysteine, which directly leads to a decrease in GM [gray matter] atrophy, thereby slowing cognitive decline. Our results show that B-vitamin supplementation can slow the atrophy of specific brain regions that are a key component of the AD [Alzheimer's disease] process and that are associated with cognitive decline.".

Fresh vegetables are essential - curry, celery, broccoli, cauliflower, and walnuts contain antioxidants and other compounds that protect your brain health and may even stimulate the production of new brain cells.
 
Coconut oil is another healthful fat for brain function. According to research by Dr. Mary Newport, just over two tablespoons of coconut oil (about 35 ml or 7 level teaspoons) would supply you with the equivalent of 20 grams of medium-chain triglycerides (MCT), which is indicated as either a preventative measure against degenerative neurological diseases or as a treatment for an already established case.