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.
Whole grains, which you digest slowly, provide fuel for your brain. (Although your brain accounts for only 3 percent of your total body weight, it uses 20 percent of energy.) Rich sources include brown rice, whole wheat bread, quinoa, bran flakes, oats, and barley. According to Science Daily, brain food containing whole grains can boost cardiovascular health, which in turn enhances the flow of blood to the brain. They contain more intact nutrients than processed white flour, including vitamin E, antioxidants, and fiber. When these work together to increase blood flow, the integrity of brain cells is better preserved. To keep your brain sharp, go beyond your diet and incorporate these healthy brain-boosting habits into your routine.
Upon examining the photographs, I noticed no difference in eye color, but it seems that my move had changed the ambient lighting in the morning and so there was a clear difference between the two sets of photographs! The before photographs had brighter lighting than the after photographs. Regardless, I decided to run a small survey on QuickSurveys/Toluna to confirm my diagnosis of no-change; the survey was 11 forced-choice pairs of photographs (before-after), with the instructions as follows:
Because it’s so nutrient-dense — packing loads of vitamins, minerals and nutrients with very little calories — it’s a great snack option if you’re looking to shed pounds. And while we often eat celery stalks, don’t skip the seeds and leaves; both provide extra health benefits and taste great in things like stir fries and soups. Not sure where to begin with eating more celery? Try my easy Ants on a Log or refreshing Super Hydrator Juice recipes.
In fact, when combined into a variety of different supplement “stacks” and taken in the correct dosage, these compounds – usually referred to as either smart drugs or nootropics (but now also including the category of psychedelics) – can completely change how your brain performs, including impacting receptor sites for neurotransmitters, altering levels of enzymes that break down specific neurotransmitters, changing cell membrane structures and thus controlling the movement of molecules inside and outside of the cell, increasing cerebral perfusion, which improves blood flow to the brain, affecting what are called “biogenic processes”, including neuronal cell creation or “neurogenesis”, and neuroendocrine regulation, regulating hormonal processes of the body specifically related to cognition (See additional studies here, here, here and here.).

The hormone testosterone (; FDA adverse events) needs no introduction. This is one of the scariest substances I have considered using: it affects so many bodily systems in so many ways that it seems almost impossible to come up with a net summary, either positive or negative. With testosterone, the problem is not the usual nootropics problem that that there is a lack of human research, the problem is that the summary constitutes a textbook - or two. That said, the 2011 review The role of testosterone in social interaction (excerpts) gives me the impression that testosterone does indeed play into risk-taking, motivation, and social status-seeking; some useful links and a representative anecdote:

There are a variety of substances to get magnesium from. Considerable enthusiasm for the new compound magnesium l-threonate was stirred by 2 small animal rat studies finding that magnesium l-threonate was able to increase magnesium levels in the brain and improve learning/memory tasks. (There are no published human trials as of October 2015, and evidence of publication bias, which I take as evidence against there being large effects in humans.) Animal studies mean very little, of course (see the appendix), but I thought it’d be interesting to try using l-threonate, so I bought the $30 Life Extension Neuro-Mag Magnesium L-Threonate with Calcium and Vitamin D3 (205g), which according to the LEF product page works out to ~60g of Magtein™ magnesium L-threonate and ~4.31g elemental magnesium inasmuch as LEF claims 2000mg of threonate powder provides 144mg elemental magnesium or a 14:1 ratio. (I don’t need the calcium or vitamin D3, but this was the only magnesium l-threonate on Amazon.) Experiment-wise, I’ll probably look at sleep metrics and Mnemosyne performance; I put off designing a blind self-experiment until after trying some.
Nootropics are classically defined as something that a) improves brain health, and b) does no harm. So, while many treatments being advertised online and on TV can be classified as nootropics, some of them don’t fit the bill because of the dangerous and damaging side effects they also confer upon the unwary consumer. In fact, most of the results you might get from searching ‘best brain pills’ are similarly not that great, let alone the best.
Nootropics (/noʊ.əˈtrɒpɪks/ noh-ə-TROP-iks) (colloquial: smart drugs and cognitive enhancers) are drugs, supplements, and other substances that may improve cognitive function, particularly executive functions, memory, creativity, or motivation, in healthy individuals.[1] While many substances are purported to improve cognition, research is at a preliminary stage as of 2018, and the effects of the majority of these agents are not fully determined.