If all of this sounds great to you, get ready to level up your brain to game like a god with GodMode. Unless, you know, you're under 18, pregnant, potentially have any pre-existing medical conditions, are taking any prescription medications, are otherwise ingesting caffeine or taking other stimulants, or you don't want to drop $60 on gamer pills. Then, you know, don't.
This doesn’t fit the U-curve so well: while 60mg is substantially negative as one would extrapolate from 30mg being ~0, 48mg is actually better than 15mg. But we bought the estimates of 48mg/60mg at a steep price - we ignore the influence of magnesium which we know influences the data a great deal. And the higher doses were added towards the end, so may be influenced by the magnesium starting/stopping. Another fix for the missingness is to impute the missing data. In this case, we might argue that the placebo days of the magnesium experiment were identical to taking no magnesium at all and so we can classify each NA as a placebo day, and rerun the desired analysis:

This was so unexpected that I wondered if I had somehow accidentally put the magnesium pills into the placebo pill baggie or had swapped values while typing up the data into a spreadsheet, and checked into that. The spreadsheet accorded with the log above, which rules out data entry mistakes; and looking over the log, I discovered that some earlier slip-ups were able to rule out the pill-swap: I had carelessly put in some placebo pills made using rice, in order to get rid of them, and that led to me being unblinded twice before I became irritated enough to pick them all out of the bag of placebos - but how could that happen if I had swapped the groups of pills?

In 2011, a story surfaced that struck fear into many: A woman was being treated for brain and memory disorders, when in reality she was just incredibly low in B12 stores. Turns out, this isn’t uncommon; many physicians don’t run routine blood tests for the nutrient, which is especially troublesome considering that our ability to absorb B12 is dramatically reduced with age. Over time, low vitamin B12 can do a number of your cognition.

As for newer nootropic drugs, there are unknown risks. “Piracetam has been studied for decades,” says cognitive neuroscientist Andrew Hill, the founder of a neurofeedback company in Los Angeles called Peak Brain Institute. But “some of [the newer] compounds are things that some random editor found in a scientific article, copied the formula down and sent it to China and had a bulk powder developed three months later that they’re selling. Please don’t take it, people!”
Took pill #6 at 12:35 PM. Hard to be sure. I ultimately decided that it was Adderall because I didn’t have as much trouble as I normally would in focusing on reading and then finishing my novel (Surface Detail) despite my family watching a movie, though I didn’t notice any lack of appetite. Call this one 60-70% Adderall. I check the next evening and it was Adderall.
A key ingredient of Noehr’s chemical “stack” is a stronger racetam called Phenylpiracetam. He adds a handful of other compounds considered to be mild cognitive enhancers. One supplement, L-theanine, a natural constituent in green tea, is claimed to neutralise the jittery side-effects of caffeine. Another supplement, choline, is said to be important for experiencing the full effects of racetams. Each nootropic is distinct and there can be a lot of variation in effect from person to person, says Lawler. Users semi-annonymously compare stacks and get advice from forums on sites such as Reddit. Noehr, who buys his powder in bulk and makes his own capsules, has been tweaking chemicals and quantities for about five years accumulating more than two dozens of jars of substances along the way. He says he meticulously researches anything he tries, buys only from trusted suppliers and even blind-tests the effects (he gets his fiancée to hand him either a real or inactive capsule).
In addition to this, privilege also plays an important role in this epidemic. "Not everyone has access to eat healthily", she mentions. In fact, she recalls an anecdote in which a supermarket owner noticed how people living off food stamps rarely use them to buy fruits and vegetables. Curious about this trend, the owner approached someone with food stamps, to which she admitted she didn't buy them because she didn't know the price prior to weighing them and felt ashamed of asking. His solution? Pre-cutting and packaging fruits in order to make them more accessible to those with lower incomes. 
Difficulty concentrating.  As mentioned previously, this may not be a direct result of age—though it can be a common side-effect of struggling with fatigue and brain fog.  When it takes more mental energy to think, it is harder to stay with it for a long time.  Many of us also are surrounded by distractions clambering for our limited attention.  Modern life is fast-paced, stressful, and overcrowded.
Bacopa Monnieri is probably one of the safest and most effective memory and mood enhancer nootropic available today with the least side-effects. In some humans, a majorly extended use of Bacopa Monnieri can result in nausea. Amongst AlternaScript’s, primary products is Optimind, a nootropic supplement which largely constitutes of Bacopa Monnieri as one of the main ingredients.
It is not because of the few thousand francs which would have to be spent to put a roof [!] over the third-class carriages or to upholster the third-class seats that some company or other has open carriages with wooden benches. What the company is trying to do is to prevent the passengers who can pay the second class fare from traveling third class; it hits the poor, not because it wants to hurt them, but to frighten the rich. And it is again for the same reason that the companies, having proved almost cruel to the third-class passengers and mean to the second-class ones, become lavish in dealing with first-class passengers. Having refused the poor what is necessary, they give the rich what is superfluous.

Microdosing With Psilocybin: Psilocybin, AKA “magic mushrooms”, are naturally occurring fungi, with over 180 different species and research from archaeologist evidence has shown that humans have been using psilocybin mushrooms for over 7,000 years. I’ve personally found microdoses of psilocybin, AKA “magic mushrooms”, to be best for nature immersions, hiking, journaling or self-discovery.  Psilocybin primarily interacts with the serotonin receptors in the brain and has been used in therapeutic settings to treat disorders such as headaches, anxiety, depression, addiction, and obsessive-compulsive disorders (See additional studies here, here, here and here). There is limited data to show any adverse drug interactions with the use of psilocybin, and liver function, blood sugar, and hormonal regulation all appear to be unaffected during consumption (although it is best to avoid alcohol and any serotonin-based antidepressants while taking any psychedelics) (See studies here, here and here). A microdose of psilocybin is generally between 0.2 grams and .5 grams, and I’d highly recommend you start on the low end of the dosage range with these or any of the psychedelics mentioned here.

Caffeine metabolism is primarily determined by the cytochrome enzyme P-450 1A2 (CYP1A2), and studies have shown that different ethnic populations exhibit widely varying expressions of the gene responsible for CYP1A2. Evidence suggests that a particular CYP1A2 impacts caffeine consumption by modifying the risks of certain diseases that are associated with caffeine consumption. It has also been shown that variations in the expression of genes that code for adenosine and dopamine receptors play a role in mediating your response to caffeine. For example, in Caucasians, the presence of certain genetic expressions for both adenosine and dopamine receptors is associated with caffeine-induced anxiety. Variations in CYP1A2 are also responsible for the speed at which different people metabolize caffeine.
As mentioned above, eating foods that are rich in indigestible fibre such as vegetables and fruits, as well as eating good fats that are found in grass-fed butter, nuts and seeds, olive oil, coconut oil and avocado, provide bacteria with prebiotics that help to produce the ‘friendly’ short-chain fatty acids such as butyrate. Avoiding processed foods that contain calcium propionate, which lead to higher levels of propionic acid - the not so friendly short-chain fatty acid - is also another key strategy to support the gut-brain link.
But what does this all have to do with food? Our gut helps keep our body’s immune responses and inflammation under control. Additionally, gut hormones that enter the brain or are produced in the brain influence cognitive ability, like understanding and processing new information, staying focused on the task at hand and recognizing when we’re full. (3)
The advantage of adrafinil is that it is legal & over-the-counter in the USA, so one removes the small legal risk of ordering & possessing modafinil without a prescription, and the retailers may be more reliable because they are not operating in a niche of dubious legality. Based on comments from others, the liver problem may have been overblown, and modafinil vendors post-2012 seem to have become more unstable, so I may give adrafinil (from another source than Antiaging Central) a shot when my modafinil/armodafinil run out.
Vinpocetine: This chemical is a semi-synthetic derivative of an extract from periwinkle.  It acts as a potent anti-inflammatory agent, and has also received some testing as a supplement for memory enhancement.  While research results are inconclusive right now, this chemical has been shown to increase blood circulation and metabolism in the brain and may slow down neuron loss.  Some tests have also shown that it can improve concentration and attention.
Or in other words, since the standard deviation of my previous self-ratings is 0.75 (see the Weather and my productivity data), a mean rating increase of >0.39 on the self-rating. This is, unfortunately, implying an extreme shift in my self-assessments (for example, 3s are ~50% of the self-ratings and 4s ~25%; to cause an increase of 0.25 while leaving 2s alone in a sample of 23 days, one would have to push 3s down to ~25% and 4s up to ~47%). So in advance, we can see that the weak plausible effects for Noopept are not going to be detected here at our usual statistical levels with just the sample I have (a more plausible experiment might use 178 pairs over a year, detecting down to d>=0.18). But if the sign is right, it might make Noopept worthwhile to investigate further. And the hardest part of this was just making the pills, so it’s not a waste of effort.
These are the most highly studied ingredients and must be combined together to achieve effective results. If any one ingredient is missing in the formula, you may not get the full cognitive benefits of the pill. It is important to go with a company that has these critical ingredients as well as a complete array of supporting ingredients to improve their absorption and effectiveness. Anything less than the correct mix will not work effectively.

The Nootroo arrives in a shiny gold envelope with the words “proprietary blend” and “intended for use only in neuroscience research” written on the tin. It has been designed, says Matzner, for “hours of enhanced learning and memory”. The capsules contain either Phenylpiracetam or Noopept (a peptide with similar effects and similarly uncategorised) and are distinguished by real flakes of either edible silver or gold. They are to be alternated between daily, allowing about two weeks for the full effect to be felt. Also in the capsules are L-Theanine, a form of choline, and a types of caffeine which it is claimed has longer lasting effects.

As it happened, Health Supplement Wholesalers (since renamed Powder City) offered me a sample of their products, including their 5g Noopept powder ($13). I’d never used HSW before & they had some issues in the past; but I haven’t seen any recent complaints, so I was willing to try them. My 5g from batch #130830 arrived quickly (photos: packaging, powder contents). I tried some (tastes just slightly unpleasant, like an ultra-weak piracetam), and I set about capping the fluffy white flour-like powder with the hilariously tiny scoop they provide.
Artichoke + Forskolin: There is plenty of evidence that suggests artichoke extract supplements (made from the leaves of artichokes) offer strong neural antioxidant properties. Additionally, Forskolin (Coleus forskohlii) is one of the few studied compounds known to naturally boost cAMP (Cyclic Adenosine Monophosphate) in your brain and is also important for neural signaling within brain cells (291m 292). I’ve experienced noticeably enhanced memory and word recall when consuming this combo. Tim Ferriss talked about this one a bit in my podcast with him, particularly referencing its presence in the somewhat popular cognition supplement “CILTEP”. Made primarily from artichoke extracts and forskolin, CILTEP is a stack that also contains vitamin B6, L-phenylalanine and acetyl-L-carnitine.  It is recommended to take two to three capsules at the beginning of each day and to skip dosage one or two days per week to achieve optimal results.
[…] The 7 Best Brain Boosting Supplements | Live in the Now … – Natural Health Recipes » Top 12 supplements for brain on October 18, 2012 at 7:37 AM … Gingko Biloba, Phosphatidyl Serine and Coenzyme Q10. Opt for the best brain supplements and stay fit with an active brain. You should be very careful while choosing the right supplement […] Reply. […]
Another promising "smart pill" is phosphatidylserine, or PS, a natural substance that helps cell walls stay pliable and is thought to boost the effectiveness of neurotransmitters, which relay brain signals. In a May 1991 study published in Neurology, neuroscientist Thomas Crook found that patients with age-associated memory impairment improved their scores on key performance tests after 12 weeks on PS. Yet more research is needed before doctors can know that the supplement is safe and effective.
Before taking any supplement or chemical, people want to know if there will be long term effects or consequences, When Dr. Corneliu Giurgea first authored the term “nootropics” in 1972, he also outlined the characteristics that define nootropics. Besides the ability to benefit memory and support the cognitive processes, Dr. Giurgea believed that nootropics should be safe and non-toxic.