Working memory has been likened to a mental scratch pad: you use it to keep relevant data in mind while you're completing a task. (Imagine a cross-examination, in which a lawyer has to keep track of the answers a witness has given and formulate new questions based on them.) In one common test subjects are shown a series of items - usually letters or numbers - and then presented with challenges: was this number or letter in the series? Was this one? In the working-memory tests, subjects performed better on neuroenhancers, though several of the studies suggested that the effect depended on how good a subject's working memory was to begin with: the better it was, the less benefit the drugs provided.
Either prescription or illegal, daily use of testosterone would not be cheap. On the other hand, if I am one of the people for whom testosterone works very well, it would be even more valuable than modafinil, in which case it is well worth even arduous experimenting. Since I am on the fence on whether it would help, this suggests the value of information is high.

Of course, work pressure, post-Christmas financial constraints and time away from family and friends can make us all feel low, however, this can happen on any date depending on our own personal circumstances. Rather than taking a ‘duvet day’ to bail out of commitments on Blue Monday, as the media is suggesting, why not take a more positive stance and engage in some activities that are tried and tested tools to help support better mood? After all, as the evidence suggests, the date or day of the week is unlikely to change these worries for the majority of us. For example, doing some exercise and eating a healthy meal with good company are both scientifically proven to support our mental wellbeing. Low-intensity exercise such as walking sustained over an extended period can help release proteins called neurotrophic factors that improve brain function and support mood, and nutrients such as B12 and Omega 3, are just two of many that have been shown to improve symptoms associated to depression. Our Nutrition Solutions offers more information on nutrition for depression if you want to know more about practical actions you can take yourself through nutrition to prevent or tackle depression.


I noticed what may have been an effect on my dual n-back scores; the difference is not large (▃▆▃▃▂▂▂▂▄▅▂▄▂▃▅▃▄ vs ▃▄▂▂▃▅▂▂▄▁▄▃▅▂▃▂▄▂▁▇▃▂▂▄▄▃▃▂▃▂▂▂▃▄▄▃▆▄▄▂▃▄▃▁▂▂▂▃▂▄▂▁▁▂▄▁▃▂▄) and appears mostly in the averages - Toomim’s quick two-sample t-test gave p=0.23, although a another analysis gives p=0.138112. One issue with this before-after quasi-experiment is that one would expect my scores to slowly rise over time and hence a fish oil after would yield a score increase - the 3.2 point difference could be attributable to that, placebo effect, or random variation etc. But an accidentally noticed effect (d=0.28) is a promising start. An experiment may be worth doing given that fish oil does cost a fair bit each year: randomized blocks permitting an fish-oil-then-placebo comparison would take care of the first issue, and then blinding (olive oil capsules versus fish oil capsules?) would take care of the placebo worry.

Is 200 enough? There are no canned power functions for the ordinal logistic regression I would be using, so the standard advice is to estimate power by simulation: generating thousands of new datasets where we know by construction that the binary magnesium variable increases MP by 0.27 (such as by bootstrapping the original Noopept experiment’s data), and seeing how often in this collection the cutoff of statistical-significance is passed when the usual analysis is done (background: CrossValidated or Power Analysis and Sample Size Estimation using Bootstrap). In this case, we leave alpha at 0.05, reuse the Noopept experiment’s data with its Magtein correlation, and ask for the power when n=200


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:
Chatterjee told me that many people who come to his clinic are cognitively preoccupied versions of what doctors call the "worried well". He had just seen a middle-aged woman, a successful Philadelphia lawyer, who mentioned having to struggle a bit to come up with certain names. "Here's an example of someone who by most measures is doing perfectly fine," Chatterjee said. "She's not having any trouble at work. But she notices she's having some problems, and it's very hard to know how much of that is just getting older." Of course, people in her position could strive to get regular exercise and plenty of intellectual stimulation, both of which have been shown to help maintain cognitive function. But maybe they're already doing so and want a bigger mental rev-up, or maybe they want something easier than sweaty workouts and Russian novels: they want a pill.
Pyritinol: Pyritinol has anti-oxidant effects for supporting the long-term health of the brain. But its primary benefit is aiding glucose uptake for periods of extended mental strain. If you are studying or working for a long period of time, your brain will start to diminish its glucose (sugar) stores which are the primary way that the brain derives its energy.
Cocoa flavanols (CF) positively influence physiological processes in ways which suggest that their consumption may improve aspects of cognitive function. This study investigated the acute cognitive and subjective effects of CF consumption during sustained mental demand. In this randomized, controlled, double-blinded, balanced, three period crossover trial 30 healthy adults consumed drinks containing 520 mg, 994 mg CF and a matched control, with a 3-day washout between drinks. Assessments included the state anxiety inventory and repeated 10-min cycles of a Cognitive Demand Battery comprising of two serial subtraction tasks (Serial Threes and Serial Sevens), a Rapid Visual Information Processing (RVIP) task and a mental fatigue scale, over the course of 1 h. Consumption of both 520 mg and 994 mg CF significantly improved Serial Threes performance. The 994 mg CF beverage significantly speeded RVIP responses but also resulted in more errors during Serial Sevens. Increases in self-reported mental fatigue were significantly attenuated by the consumption of the 520 mg CF beverage only. This is the first report of acute cognitive improvements following CF consumption in healthy adults. While the mechanisms underlying the effects are unknown they may be related to known effects of CF on endothelial function and blood flow.
These actually work! I purchased these because of some focus and clarity issues. I like that there are two formulas, one for morning and one for night, and that they both help with the appropriate things at the appropriate times. The pills are easy to take, and not too large, which I have found to be an issue with some other supplements. They are capsules with what appears to be powder in them and appear to be well-made. There is no funky after taste or after effects. When several other natural approaches have not worked, these did, and the wait to see a difference was not long at all! The increase in focus and clarity and even some energy was evident within 2 days. They also come in 60 count bottles, so if you only take 1 per day, they will last 2 months!! I am incredibly impressed with these supplements and will likely be ordering them again.
Microdosing involves ingesting small amounts of psychedelics to induce a very subtle physical and mental effect accompanied by a very noticeable, overall positive, health effect. When you take a microdose of a psychedelic, it is typically referred to as a sub-perceptual dose. A sub-perceptual dose will not have a major impact on your ability to function normally, but the effect will definitely be present in your mood and behavior. The microdose of a particular psychedelic is correlated to the lowest dose that will produce a noticeable effect, which is also known as the threshold dose. Since the goal is not to get a hallucinogenic effect, a microdose can be well below the psychedelics threshold dose. By integrating the correct doses of psychedelics into your weekly routine, you can achieve higher creativity levels, more energy, improved mood, increased focus, and better relational skills. There is a growing body of research that shows microdosing to improve depression, anxiety, PTSD, and emotional imbalance, help with alcohol and tobacco addiction, and decrease ADD and ADHD behaviors.

Adderall, a stimulant composed of mixed amphetamine salts, is commonly prescribed for children and adults who have been given a diagnosis of attention-deficit hyperactivity disorder (ADHD). But in recent years Adderall and Ritalin, another stimulant, have been adopted as cognitive enhancers: drugs that high-functioning, overcommitted people take to become higher-functioning and more overcommitted. (Such use is "off label", meaning that it does not have the approval of either the drug's manufacturer or the FDA, America's Food and Drug Administration.) College campuses have become laboratories for experimentation with neuroenhancement, and Alex was an ingenious experimenter. His brother had received a diagnosis of ADHD, and in his first year as an undergraduate Alex obtained an Adderall prescription for himself by describing to a doctor symptoms that he knew were typical of the disorder. During his college years, Alex took 15mg of Adderall most evenings, usually after dinner, guaranteeing that he would maintain intense focus while losing "any ability to sleep for approximately eight to 10 hours". In his second year, he persuaded the doctor to add a 30mg "extended-release" capsule to his daily regime.


The general cost of fish oil made me interested in possible substitutes. Seth Roberts uses exclusively flaxseed oil or flaxseed meal, and this seems to work well for him with subjective effects (eg. noticing his Chinese brands seemed to not work, possibly because they were unrefrigerated and slightly rancid). It’s been studied much less than fish oil, but omega acids are confusing enough in general (is there a right ratio? McCluskey’s roundup gives the impression claims about ratios may have been overstated) that I’m not convinced ALA is a much inferior replacement for fish oil’s mixes of EPA & DHA.

Obviously, as you can see, there are a host of benefits to the better living through science to be had through optimizing your brain with specific compounds. So, putting aside the intriguing topic of psychedelics for the moment (yes, yes, I know you probably want to know how to microdose with LSD or psilocybin), what’s the difference between a smart drug and a nootropic, and how do you choose which to take? You’re about to find out.
The Neurohacker Collective is a group of scientists, academics, and creatives who, among other things, sell nootropics. One of its premier products is Qualia Original Stack (OS), which has 41 ingredients. The large print says it improves focus, mood, and energy within 30 minutes and “supports long-term brain health.” A 22-dose supply costs $129. Such stacks operate on the idea that synergies among ingredients yield additional benefits.
This supplement contains Vitamins A, C, D, E, B1, B2, B3, and B6, Folate, Biotin, Pantothenic Acid, Copper, Calcium, Selenium, Iron, Manganese, Chromium, Potassium, Molybdenum, Iodine, Magnesium, Zinc, and 692mg of Synergistic and Proprietary Formulation that includes Dimethylaminoethanol, L-Glutamine, Bacopin, L-pyroglutamic Acid, Phyosphatidylserine, DHA Concentrate, Choline, Inositol, N-Acetyl Tyrosine, Bilberry Fruit, Gamma Aminobutyric Acid, Grape Seed Extract, Vinpocetine, Trace Lyte Electrolyte Concentrate, Huperzine A, Boron, and Vanadium.
I have elsewhere remarked on the apparent lack of benefit to taking multivitamins and the possible harm; so one might well wonder about a specific vitamin like vitamin D. However, a multivitamin is not vitamin D, so it’s no surprise that they might do different things. If a multivitamin had no vitamin D in it, or if it had vitamin D in different doses, or if it had substances which interacted with vitamin D (such as calcium), or if it had substances which had negative effects which outweigh the positive (such as vitamin A?), we could well expect differing results. In this case, all of those are true to varying extents. Some multivitamins I’ve had contained no vitamin D. The last multivitamin I was taking both contains vitamins used in the negative trials and also some calcium; the listed vitamin D dosage was a trivial ~400IU, while I take >10x as much now (5000IU).
Some supplement blends, meanwhile, claim to work by combining ingredients – bacopa, cat's claw, huperzia serrata and oat straw in the case of Alpha Brain, for example – that have some support for boosting cognition and other areas of nervous system health. One 2014 study in Frontiers in Aging Neuroscience, suggested that huperzia serrata, which is used in China to fight Alzheimer's disease, may help slow cell death and protect against (or slow the progression of) neurodegenerative diseases. The Alpha Brain product itself has also been studied in a company-funded small randomized controlled trial, which found Alpha Brain significantly improved verbal memory when compared to adults who took a placebo.
The easiest way to use 2mg was to use half a gum; I tried not chewing it but just holding it in my cheek. The first night I tried, this seemed to work well for motivation; I knocked off a few long-standing to-do items. Subsequently, I began using it for writing, where it has been similarly useful. One difficult night, I wound up using the other half (for a total of 4mg over ~5 hours), and it worked but gave me a fairly mild headache and a faint sensation of nausea; these may have been due to forgetting to eat dinner, but this still indicates 3mg should probably be my personal ceiling until and unless tolerance to lower doses sets in.
On 8 April 2011, I purchased from Smart Powders (20g for $8); as before, some light searching seemed to turn up SP as the best seller given shipping overhead; it was on sale and I planned to cap it so I got 80g. This may seem like a lot, but I was highly confident that theanine and I would get along since I already drink so much tea and was a tad annoyed at the edge I got with straight caffeine. So far I’m pretty happy with it. My goal was to eliminate the physical & mental twitchiness of caffeine, which subjectively it seems to do.
Is 200 enough? There are no canned power functions for the ordinal logistic regression I would be using, so the standard advice is to estimate power by simulation: generating thousands of new datasets where we know by construction that the binary magnesium variable increases MP by 0.27 (such as by bootstrapping the original Noopept experiment’s data), and seeing how often in this collection the cutoff of statistical-significance is passed when the usual analysis is done (background: CrossValidated or Power Analysis and Sample Size Estimation using Bootstrap). In this case, we leave alpha at 0.05, reuse the Noopept experiment’s data with its Magtein correlation, and ask for the power when n=200
On the nutritional naughty list for years, egg yolks are finally experiencing their well-deserved day in the sun. If you’ve been eating only egg whites, the yolk’s on you. Yolks contain large amounts of choline, which helps in fetal brain development for pregnant women. It also breaks down bethane, a chemical that produces hormones related to happiness. That’s right, eggs can make you happy! (6)
One SCFA in particular, called propionic acid, has been identified as a driver for abnormal behaviour that is related to both ADHD and the autism spectrum. This SCFA can alter metabolic and immune pathways, as well as gene expression, which can affect the functionality of the brain cells and their receptivity to neurotransmitters, as well as their ability to regenerate and regulate inflammatory responses. Certain strains of pathogenic bacteria, such as clostridia, have been implicated in producing large amounts of propionic acid. This strain of bacteria is naturally present in the gut, however, an overgrowth can occur when good bacteria levels are compromised and/or there is an acute infection. In addition, processed wheat and dairy products often contain propionic acid as a food preservative in the form of calcium propionate.
But how to blind myself? I used my pill maker to make 9 OO pills of piracetam mix, and then 9 OO pills of piracetam mix+the Adderall, then I put them in a baggy. The idea is that I can blind myself as to what pill I am taking that day since at the end of the day, I can just look in the baggy and see whether a placebo or Adderall pill is missing: the big capsules are transparent so I can see whether there is a crushed-up blue Adderall in the end or not. If there are fewer Adderall than placebo, I took an Adderall, and vice-versa. Now, since I am checking at the end of each day, I also need to remove or add the opposite pill to maintain the ratio and make it easy to check the next day; more importantly I need to replace or remove a pill, because otherwise the odds will be skewed and I will know how they are skewed. (Imagine I started with 4 Adderalls and 4 placebos, and then 3 days in a row I draw placebos but I don’t add or remove any pills; the next day, because most of the placebos have been used up, there’s only a small chance I will get a placebo…)
“Over the years, I have learned so much from the work of Dr. Mosconi, whose accomplished credentials spanning both neuroscience and nutrition are wholly unique. This book represents the first time her studies on the interaction between food and long-term cognitive function reach a general audience. Dr. Mosconi always makes the point that we would eat differently and treat our brains better if only we could see what we are doing to them. From the lab to the kitchen, this is extremely valuable and urgent advice, complete with recommendations that any one of us can take.”

"More and more of our young people are using these drugs to help them work. They've got their laptop, their iPhone, and their Adderall. This rising generation of workers and leaders may have a subtly different style of thinking and working, because they're using these drugs or because they learned to work using these drugs, so that even if you take the drugs away they'll still have a certain approach. I'm a little concerned that we could be raising a generation of very focused accountants."
After a month of testing nootropics, I’m not ready to commit to them permanently. They’re simply too untested, and while “move fast and break things” might be a good approach to building software, it’s not what I want for my brain. Still, I think we’ll likely hear more about nootropics, especially as recreational users of more powerful prescription drugs like Adderall and modafinil look for less harsh alternatives. Sometimes, when you’re working, you don’t want to put your brain on jet fuel—a little unleaded gas will do. And for those moments, nootropics could be a fertile testing ground for the intrepid body-hacker.
Please browse our website to learn more about how to enhance your memory. Our blog contains informative articles about the science behind nootropic supplements, specific ingredients, and effective methods for improving memory. Browse through our blog articles and read and compare reviews of the top rated natural supplements and smart pills to find everything you need to make an informed decision.

Breathing carefully, I clutched the Costco special edition family size 1.5-liter glass bottle of vodka and carefully extracted 10 milliliters with a miniature glass pipette, which I then transferred into a small amber glass bottle. Then, with my nine-year-old son’s tiny set of school scissors, I snipped exactly 1/10 of LSD from the blotter square I’d ordered from a psychedelic research chemical supplier website the week prior, with a cloaked browser, of course, so the feds didn’t come knocking at my door. I dropped the LSD into the bottle, gave it a thirty-second shake, then placed the bottle in the pantry, next to my protein powder and creatine. I smiled. Within 24 hours, I’d be ready to sample my first homemade, volumetric “microdose” of a drug reported to increase lateral thinking patterns, improve creativity, massively boost productivity and much, much more.


The next cheap proposition to test is that the 2ml dose is so large that the sedation/depressive effect of nicotine has begun to kick in. This is easy to test: take much less, like half a ml. I do so two or three times over the next day, and subjectively the feeling seems to be the same - which seems to support that proposition (although perhaps I’ve been placebo effecting myself this whole time, in which case the exact amount doesn’t matter). If this theory is true, my previous sleep results don’t show anything; one would expect nicotine-as-sedative to not hurt sleep or improve it. I skip the day (no cravings or addiction noticed), and take half a ml right before bed at 11:30; I fall asleep in 12 minutes and have a ZQ of ~105. The next few days I try putting one or two drops into the tea kettle, which seems to work as well (or poorly) as before. At that point, I was warned that there were some results that nicotine withdrawal can kick in with delays as long as a week, so I shouldn’t be confident that a few days off proved an absence of addiction; I immediately quit to see what the week would bring. 4 or 7 days in, I didn’t notice anything. I’m still using it, but I’m definitely a little nonplussed and disgruntled - I need some independent source of nicotine to compare with!
Our 2nd choice for a Brain and Memory supplement is Clari-T by Life Seasons. We were pleased to see that their formula included 3 of the 5 necessary ingredients Huperzine A, Phosphatidylserine and Bacopin. In addition, we liked that their product came in a vegetable capsule. The product contains silica and rice bran, though, which we are not sure is necessary.
Pop this pill and improve your memory. Swallow that one and reduce your cognitive decline. We see ads for such products all the time and I suspect they will increase as the baby boomers reach senior citizenhood. The most popular brain boosting supplements are fish oil pills and they are also probably the best studied ones. The results are not encouraging. When all the studies are pooled, we are left with the possibility of a barely significant improvement in recalling lists of words soon after they have been learned, but the effect does not last. Extracts of the ginkgo biloba tree are also popular, and here the prospects are even dimmer. There is no impact on memory, despite claims of increased circulation in the brain. And ginkgo can interfere with the action of anticoagulants and has also been shown to be an animal carcinogen.
Mercury, as well as other heavy metals such as lead, can accumulate in brain tissue, as well as in the spinal cord, as they are fat-soluble - meaning that they can hide itself in fat tissue, which is abundant in both the brain and the spine. Once there, they can displace important nutrients for brain health such as zinc and iron, which are needed for neurotransmitter production, as well as induce an inflammatory process called oxidative stress among other things.

The truth is that, almost 20 years ago when my brain was failing and I was fat and tired, I did not know to follow this advice. I bought $1000 worth of smart drugs from Europe, took them all at once out of desperation, and got enough cognitive function to save my career and tackle my metabolic problems. With the information we have now, you don’t need to do that. Please learn from my mistakes!


Ginkgo Biloba, Bacopa Monnieri, and Lion’s Mane: This particular unique blend boosts mental focus, memory, learning, and cognitive performance while reducing anxiety and depression, and I’ve found that it can significantly boost mental alertness for around six hours at a time without any jitteriness or irritability – or any significant amounts of caffeine. It’s important to allow for a grace period of about 12 weeks before you feel the stack’s full potential, so don’t expect immediate results with this combination.
Much of what she says is standard health advice. Avoid trans fats. Eat fresh vegetables and fruit. Avoid processed foods. Limit red meat consumption. It’s better to get your nutrients from food than from supplement pills. Exercise, get adequate sleep, and avoid stress. Since the brain runs on glucose, she wouldn’t agree with the low-carb diet folks; she says we need adequate sources of glucose in our diet, and recommends complex carbs, paying attention to the glycemic index.
When many of us think of memory enhancers, we think of ginkgo biloba, the herb that now generates more than $240 million in sales a year worldwide. The October 22-29, 1997 issue of the Journal of the American Medical Association reported that Alzheimer's patients who took 120 mg of ginkgo showed small improvements in tests designed to measure mental performance.
The compound has great nootropic properties that includes memory enhancement and protection against brain aging. There are studies that suggest that the compound is an effective treatment for disorders like vascular dementia, Alzheimer’s, brain stroke, anxiety and depression. However, there are some side effects associated with Alpha GPC, like headache, heartburn, dizziness, skin rashes, insomnia, and confusion.
Certain B vitamins - B6, B12 and folic acid - are known to reduce levels of a compound called homocysteine in the blood. Elevated levels of homocysteine are associated with increased risk of stroke, cognitive impairment and Alzheimer's disease. A study of a group of elderly patients with mild cognitive impairment found that after two years of intervention with high doses of B6, B12 and folic acid there was significantly less brain shrinkage compared to a subset given placebo treatment. Opt for B-rich foods like eggs, chicken, fish and leafy greens.
The nootropic sulbutiamine, of the synthetic B-vitamin-derived nootropics family, is generally considered a low-risk supplement; however, some users have reported that the supplement has addictive qualities. While there is no firm evidence of sulbutiamine addiction, the risk may increase at high dosages. For instance, users who consume this supplement for 10 consecutive days may experience withdrawal for two to five days. There are also increased risks when sulbutiamine is taken with antipsychotic medications.[8]
Dr Hart explained how communication between the gut and the brain is controlled via our immune system, our endocrine system (hormones) and our central nervous system, which are all under the influence of the bacteria in our gut. The types and amount of these bacteria, known as our gut microbiome, can be directly impacted by factors such as diet, stress, pollution and medications (2) and the composition of the microbiome is also understood to affect one’s susceptibility to food sensitivities and intolerances (3).  

(People aged <=18 shouldn’t be using any of this except harmless stuff - where one may have nutritional deficits - like fish oil & vitamin D; melatonin may be especially useful, thanks to the effects of screwed-up school schedules & electronics use on teenagers’ sleep. Changes in effects with age are real - amphetamines’ stimulant effects and modafinil’s histamine-like side-effects come to mind as examples.)
However, they fell short in several categories. The key issue with their product is that it does not contain DHA Omega 3 and the other essential vitamins and nutrients needed to support the absorption of Huperzine A and Phosphatidylserine. Without having DHA Omega 3 it will not have an essential piece to maximum effectiveness. This means that you would need to take a separate pill of DHA Omega 3 and several other essential vitamins to ensure you are able to reach optimal memory support. They also are still far less effective than our #1 pick’s complete array of the 3 essential brain supporting ingredients and over 30 supporting nutrients, making their product less effective.

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 Neurohacker Collective is a group of scientists, academics, and creatives who, among other things, sell nootropics. One of its premier products is Qualia Original Stack (OS), which has 41 ingredients. The large print says it improves focus, mood, and energy within 30 minutes and “supports long-term brain health.” A 22-dose supply costs $129. Such stacks operate on the idea that synergies among ingredients yield additional benefits.


Power times prior times benefit minus cost of experimentation: (0.20 \times 0.30 \times 540) - 41 = -9. So the VoI is negative: because my default is that fish oil works and I am taking it, weak information that it doesn’t work isn’t enough. If the power calculation were giving us 40% reliable information, then the chance of learning I should drop fish oil is improved enough to make the experiment worthwhile (going from 20% to 40% switches the value from -$9 to +$23.8).


That really says it all: there’s an initial spike in MP, which reads like the promised stimulative effects possibly due to fixing a deficiency (a spike which doesn’t seem to have any counterparts in the previous history of MP), followed by a drastic plunge in the magnesium days but not so much the control days (indicating an acute effect when overloaded with magnesium), a partial recovery during the non-experimental Christmas break, another plunge, and finally recovery after the experiment has ended.
This looks interesting: the Noopept effect is positive for all the dose levels, but it looks like a U-curve - low at 10mg, high at 15mg, lower at 20mg, and even lower at 30mg 48mg and 60mg aren’t estimated because they are hit by the missingness problem: the magnesium citrate variable is unavailable for the days the higher doses were taken on, and so their days are omitted and those levels of the factor are not estimated. One way to fix this is to drop magnesium from the model entirely, at the cost of fitting the data much more poorly and losing a lot of R2:
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.
The main concern with pharmaceutical drugs is adverse effects, which also apply to nootropics with undefined effects. Long-term safety evidence is typically unavailable for nootropics.[13] Racetams — piracetam and other compounds that are structurally related to piracetam — have few serious adverse effects and low toxicity, but there is little evidence that they enhance cognition in people having no cognitive impairments.[19]
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