Healthy cognitive function is a global concern for the elderly and those looking to enhance their performance.
In this article, we will give you our cognitive enhancement research and the role of nutrition.
The key sections are listed below:
- What is cognitive function?
- What is cognitive enhancement?
- How to improve cognitive performance
- Natural cognitive enhancers
- Cognitive ingredients
- Nootropic benefits
- Are nootropics safe?
- Cognitive impairment causes
- Diet for cognitive health
- Military and cognitive studies
What is Cognitive Function?
According to the World Health Organization, there is now a global health concern regarding age-related cognitive decline, and it predicts the rates of cognitive decline to rise as almost a quarter of the world's population by 2050 will be over the age of 60. 
So, what is cognitive health, decline, and associated illnesses such as dementia?
Cognitive health can be described as brain health. It is the ability of the brain to function correctly and operate cohesively with the many different functions it controls.
Remember, everything you do is directed by the brain, this can include movement, taste, feel, thought, and emotions.
The National Institute on Aging  breaks cognitive health into three simple points.
- Motor function
- Emotional function
- Sensory function
Let's look at those in a bit more depth.
All of your movements are a result of motor functioning.
If you want to pick up a glass of water and drink it, motor function is controlling that movement.
Dancing, terribly or not is down to motor function.
If someone cannot move smoothly and quickly or unaided in what we may consider a 'normal' way, then they have an issue with their motor functioning.
This could be due to a disease such as Parkinson's.
According to the National Health Service Parkinson's disease is the result of progressive damage to parts of the brain which takes place over a period of years. 
The brain is not functioning correctly, and this is an example of cognitive impairment. 
It was Arnold Schwarzenegger in the film Terminator 2 that asked the question to John Connor, “why do you cry?”.
Earlier in the film, the person he was sent to protect (John Connor) screamed at him, “you just can't go 'round killing everyone!”
The Terminator responded with, “why?” on two occasions. John Connor couldn't give an explanation other than, “you just can't!”.
It is hard to explain emotional functioning, but it is what constitutes as a healthy functioning human being.
Whilst in Terminator 2, the Cyberdyne Systems Model 101 looked human, the telltale signs were that he didn't respond to emotional situations as a human.
After all, it had living tissue over a metal endoskeleton, but it didn't have a human brain. It had a CPU chip.
This provides a great example of emotional functioning that only the brain is really capable of, and how the Terminator is easily identified as not being human to the audience watching the film, regardless of its appearance.
That emotional response of crying, of beaming with joy or taking pity on a person that needs help is your brain interpreting and responding with emotion.
The condition of schizophrenia, where a person is lacking normal emotional response and function, is a feature of cognitive dysfunction. 
Have you ever screamed as you accidentally burned your skin on a hot pan, or grumbled to yourself as you managed to get caught on a stinging nettle whilst out walking?
These are good examples of your sensory function operating. It is your brain's response to touch, temperature, pressure, and pain.
A loss of this functioning is associated with cognitive decline as it is the cumulative effects of brain changes including decreased nerve conduction, gray matter changes, and a decreased density of Meissner's and Pacinian corpuscles which help identify vibrations, touch, and pressures. 
What is Cognitive Enhancement?
The term cognitive enhancement is not necessarily associated with treating any level of cognitive decline or deteriorating brain health.
Instead, it is a word that is associated with a term called 'biohacking'.
What is Biohacking?
Literature published by Capella University states that biohacking is merely anything that we do to our bodies to increase longevity, health, or performance. 
This can be anything ranging from a healthier diet to wearable technology – think Fitbits or other devices that track energy expenditure, your heartbeat, and how far we have walked.
However, while there are very tame, simple and proven ways you can improve your health (eating more nutritious food for instance) on the other end of the spectrum, biohacking can include electronic implants, chips, sensors and even injecting DNA – almost like becoming a cyborg...and getting closer to becoming the Terminator. 
This is all in the name of biological enhancement and improvement, to 'upgrade' yourself. Just like fitting your car with a high flow exhaust and air filter system.
However, the concern regarding biohacking is that in many cases it is merely 'do it yourself' biology, science, or even medicine. 
Worse still, it appears to be peddled and pushed by people, guru's, or even self-professed experts that are not medically qualified.
While the concept of biohacking conjures up images from a science fiction film, cognitive enhancement in its basic form is very accessible and now part of the mainstream as people seek to improve their mental performance by using natural and alternative medicines. 
Therefore, while the term and concept of cognitive enhancement are broad, taking into account many different approaches and methods, it is simply the goal to improve the way you perform and enhance human brain function. 
This could be for, but not limited to the following reasons:
- Improve concentration and focus
- Be more alert
- Improve confidence
- Enhance memory and learning
At the end of the day, many people want to excel in what they perceive a competitive environment, which could be sport or employment.
Whilst taking in to account the different ways of enhancing brain function, it is the use of non-pharmaceutical means which is considered the actual method of cognitive enhancement according to an article published in the ACS Chemical Neuroscience Journal of March 2019. 
How to Improve Cognitive Performance
You may have watched the documentary Take Your Pills.
It is aired on Netflix and follows a number of people who are going through different stages of their lives who use prescription stimulants to help improve their cognitive function.
In the majority of cases, it seems like the people who the documentary focuses on use stimulant medications to help them be more competitive – to learn more and perform at a higher level.
So is that it?
To work 'harder', focus more, and be a 'better' you, the key is a prescription stimulant?
Let's take a look...
What are cognitive enhancement drugs?
In the documentary, users of prescription stimulants complain of a 'hypercompetitive' study and work environment where people are pushed harder than ever to get into the best colleges, achieve the highest grades, and then work longer hours to be a success when they get a job.
Many feel that without prescription stimulants they cannot perform as required, and need them to enhance their performance and keep up.
So what are these drugs?
Adderall is probably the most well known, followed by Ritalin.
Both are central nervous stimulants and they increase brain activity.
Adderall vs Ritalin
They both have a similar result, but the characteristics are slightly different, with Adderall acting more slowly and having a longer effect while Ritalin acts more quickly but does not last as long.
They are prescribed to people who are diagnosed with attention deficit hyperactivity disorder and can help reduce impulsive behavior whilst helping the user concentrate and focus on tasks more easily.
It's important to remember that Adderall and Ritalin are the marketing names for these drugs.
The generic name for Adderall is amphetamine/dextroamphetamine (a combination of two amphetamine enantiomers).
Whereas the generic name for Ritalin is methylphenidate.
Both are Schedule II controlled substances and require a prescription.
Both Adderall and Ritalin are amphetamines as classified by the United States Drug Enforcement Administration. 
They are classified as medical drugs but with a caveat.
That is, “...drugs with a high potential for abuse, with use potentially leading to severe psychological or physical dependence. These drugs are also considered dangerous.” 
Amphetamine Health Risks
The Food and Drug Administration (FDA) lists a number of potential dangers that are associated with the use of amphetamines. 
These can include:
- Cardiovascular risk of death
- Visual issues
Due to their legal status, selling or giving away these drugs is illegal.
So, as we can see, improving your cognitive performance is risky, and potentially illegal if you are not actually prescribed the drugs.
This doesn't sound very positive.
Data from 2015 collated by the National Survey on Drug Use and Health estimated that 17.2 million people in the United States used prescription stimulants and 5.3 million misused them, by misuse, it is meant that the user had no medical grounds to use them. 
Alarmingly, 75.8% of users reported the main reasons for taking stimulants was to:
- Stay awake
- Help with study
Stimulant Use Disorder
Prescription stimulant abuse statistics report that 426,000 of stimulant users were categorized by having a 'disorder', by which this means using the drug has caused issues with the law, work, study or home life, problems with tolerance, withdrawal and being placed in dangerous situations.
It is now that we look at safer, alternatives, which do not require a prescription.
Natural Cognitive Enhancers
Clearly there are risks to taking prescription amphetamines, especially if you do not warrant a prescription.
However, there are natural and alternative ways to improve your cognitive function that are legal and safe.
Let's look at nootropics.
Often coined as 'smart drugs', memory enhancers, or brain performance boosters nootropics are substances that are marketed as improving brain function. 
Nootropics are meant to increase and improve mental stimulus.
They are often used by already healthy adults who are looking to become more competitive, they tend to be sold as a dietary supplement and do not require a prescription.
That said, there are two types of nootropics.
Those created in a lab which are synthetic and those that are natural herbal remedies.
However, we will discuss the non-pharmaceutical, natural nootropics.
How do Nootropics Work?
Your brain requires a balance of nutrients to operate effectively.
A natural nootropic supplement works by filling any nutrient deficiencies as well as providing a variety of herbal compounds that can increase mental function. 
This can include the following:
- Memory recall
A nootropic can help with the function of the dopaminergic pathways and the cholinergic system. These mechanisms are explained in a little more detail below.
There are three dopaminergic pathways we would like to discuss. These are:
These pathways are responsible for movement, emotion, and controlling the movement of hormones through a system of blood vessels at the base of the brain. 
The cholinergic synapses are present throughout the central nervous system . They are considered to be important for the operation of the brain functions such as:
So, how does a natural nootropic work?
The brain requires different nutrients to operate effectively and healthily. Therefore, nootropics may include vitamins and minerals to feed the brain.
Furthermore, nootropics can help dilate the blood vessels and improve blood flow. This increases the oxygen and energy supplies to the organ.
It is important to note that the brain requires far more oxygen than is proportional to its mass compared to the body.
The brain weighs approximately 3% of total body weight, yet requires 15% of oxygen and blood supply to be nourished. 
In addition, some ingredients can help reduce inflammation and toxicity  which can help prevent aging of the brain as well as stimulating the neuronal cell to increase and enhance brain activity. 
There are lots of ingredients that can be found in natural nootropics that are able to enhance cognitive function.
We want to touch upon those that are clinically proven, safe, and have beneficial properties that can aid your everyday functioning.
Vitamins and minerals for cognitive function
Our body needs vitamins. They perform multiple vital roles within the body.
The Journal of International Medical Research explains their role includes bone strength, wound healing, repair cell damage, convert foods into energy, prevent fatigue, and improve the immune system. 
Our research and compiled list only contain vitamins that show a significant and strong connection between cognitive health.
An abstract from the Scandinavian Journal of Clinical Laboratory Investigation of 2012 state that they found two large studies which indicate that low levels of vitamin D may increase the risk of cognitive decline. 
A later review published in 2014 from the Clinical Interventions in Aging journal identify that a number of, '... recent studies have confirmed an association between cognitive impairment, dementia, and vitamin D deficiency...'. 
Various studies have identified the importance of the retinoid signaling pathway to ensure healthy and functional brain development.
This link is further established with observations of the deterioration of the retinoid-signaling pathway and cognitive decline, notwithstanding the development of Alzheimer's disease. 
The National Health Service of the United Kingdom also published findings that demonstrated those people with lower blood vitamin A levels also showed a higher level of cognitive impairment. 
It has been documented that an increased intake of vitamin K has resulted in improved cognition among older people. 
There's also evidence that vitamin K demonstrates anti-inflammatory action and protects against oxidative stresses whilst contributing to brain function. 
Various studies have concluded that there is a positive correlation between vitamin E supplementation and healthy brain function whilst slowing cognitive decline.
Furthermore, high doses over a long period of time have proven to be safe and free of unwanted side effects. 
The Neuropsychiatric Disease and Treatment journal concludes that iron supplementation improves cognitive function, even if that person is not deficient in iron. 
Similar results were found from studies of different aged school children who were given iron supplements. All groups showed improvements in cognitive function. 
A large study published by the British Journal of Nutrition involving nearly 400 healthy adults comparing a placebo, 15mg and doses of 30mg of zinc saw that those who were supplementing with zinc scored higher on the Cambridge Automated Neuropsychological Test Battery. 
Boron has demonstrated to improve memory recall and overall performance.
Furthermore, a restriction of boron in the diet has resulted in an adverse effect of brain function as reported by Integrative Medicine: A Clinician's Journal. 
A review of boron by the United States Department of Agriculture, Agricultural Research Service notes that there is a significant difference in cognitive performance between those with a high and low boron intake. 
Herbal Cognitive Enhancers
There are many plant compounds that are effective at reducing inflammation, toxins, and have clinical evidence demonstrating numerous biological benefits that may have a role in the prevention of diseases. 
Some botanicals have been identified as having a positive effect on brain health and function.
This itchy seed known as Velvet Bean has demonstrated in clinical trials to have a positive effect on the management of Parkinson's Disease as identified by the Journal of Neurology, Neurosurgery, and Psychiatry. 
This effect is due to mucuna pruriens containing high levels of levodopa. Levodopa is a direct precursor to dopamine which is a neurotransmitter.
It is dopamine which has a major role in cognitive function, as well as behavior along with mood, and it is mucuna pruriens that increase dopamine. 
An eight-week study using 600mg of Ashwagandha generated significant improvements for adults suffering from mild cognitive impairment.
The results saw that the ashwagandha improved memory, executive function, attention, and the speed of which information is processed. 
A further study also identifies ashwagandha as having anti-stress properties due to the believed moderating effects on the hypothalamus‐pituitary‐adrenal axis. 
It is reported that d-aspartic acid plays a pivotal role in both the central nervous system and the neuroendocrine system. 
Thus, the central nervous system can signal and send messages for hormones to be produced and released.
In 2008 the Journal of Neuroscience found evidence that highlights the use of this amino acid as a therapeutic agent for treating schizophrenia-related symptoms. 
Interesting findings published in 2019 by the Multiple Sclerosis Journal saw that daily oral ingestion of d-aspartic acid enhances synaptic plasticity which contributes to learning and memory. 
Research regarding fenugreek and cognitive function has unearthed anti-Alzheimer's benefits as it has neuroprotective effects.
This study highlights the potential use of fenugreek in the treatment of Alzheimer's disease. 
A meta-analysis of literature surround fenugreek and its therapeutic properties have confirmed that the herb, also known as Trigonella foenum-graecum, does exert neuroprotection, antidepressant, antianxiety and other benefits toward cognitive function. 
This is also known as lion's mane mushroom.
The available research states that a 3g daily dose of this mushroom over a period of 4 months resulted in an improvement of those suffering from mild cognitive impairment. 
A daily dose of 400mg appears to be the sweet spot according to a meta-analysis of the studies. However, even just 200mg has demonstrated to help improve mood and cognition after one month's use.
Although at 200mg, after two months the benefits seem to wear off. 
This is a very popular extract from the leaves of a tree. And, considering the number of studies, it is no wonder that the extracts are found in many supplements.
It has shown benefit to those suffering from dementia by improving cognitive and neuropsychiatric symptoms according to the Pharmacopsychiatry journal. 
An additional study recorded that after six weeks of daily intake there were improvements in memory and processing speeds for people of 45 years or older. 
The European Journal of Clinical Pharmacology published a study that noted the benefits of reaction time and memory from just 40mg daily. 
A further study saw that after just 30 days of use that their attention, concentration, and speech improved. 
There have been positive findings after research demonstrated that clubmoss showed improvements among a number of cognitive parameters for those suffering from Alzheimer's disease. 
While the functions are not entirely understood, studies have shown that a daily dose of 750mg does help reduce the impact of age-related cognitive decline and mood disorders. 
Bacopa is a popular herb found in some specific nootropic supplements. According to the studies, it is easy to understand why.
Even for people with no signs of cognitive decline, a daily dose of 300mg for three months saw improvements in attention, depression, and anxiety symptoms. 
An amino acid that derives from glycine.
When thirty-one schizophrenic patients were tested with a six-week dose of d-serine, their symptoms as well as cognitive performance improved. 
Derived from soybean, a six-month trial showed that for older people who have slight cognitive impairment their memory functions improved. 
The effectiveness of this herb on a number of different cognitive parameters was tested amongst young, healthy physicians.
The study found that within two weeks there was a significant improvement of these cognitive functions such as memory, calculation, concentration associative thinking, and speed of audio-visual perception. 
It is hard to separate information from credible sources and that from the marketeers.
However, having already touched upon how nootropics work, we can see there are already clear clinically proven benefits for some compound, vitamins, minerals, and herbal extracts that are the result of:
- Reduce inflammation and toxicity
In return, this means that a person can think with more clarity, their working memory is improved, concentration is better, anxiety and depressive symptoms can be reduced whilst areas such as speech, attention, and learning benefit.
These are all key areas that are proven by the clinical results as listed in the references section at the footer of the article.
Let's step back and have a think about nootropics and cognitive enhancers, or 'smart drugs'.
In this article, we have separated the prescription products from natural nootropics.
The prescription 'smart drugs' do carry many unwanted side effects that can be a hazard to a person's health.
This is why they are prescription use only.
A medical professional has to assess the person, understand their medical history, and then weigh up the safety aspects for that person to safely be administered the drug based upon a cognitive defect being present.
Prescription medication can carry a number of risks, particularly if that person has no medical requirement for them.
For instance, a prescription drug called Modafinil can cause some very serious side effects such as:
- Psychiatric disorders
- Cardiovascular issues
- Skin and multi-organ hypersensitivity
It has been reported that almost half of the reported side effects were through misuse of the drug. 
Another potential side effect of taking a prescribed pharmaceutical cognitive drug is the legal risk.
These are controlled substances in places such as Europe and the USA. Therefore, buying or selling a prescription drug could lead to criminal proceedings.
Are Nootropics Safe?
We have discussed prescription cognitive enhancers, these come with both medical and legal risks if not used in accordance with a medical professional's guidance.
However, natural nootropic supplements that include vitamins, minerals, amino acids, and herbal extracts are on the whole very safe and risk-free.
In fact, it has been said by Professor Corneliu E. Giurgea who coined the term, 'nootropic', which means enhancement of learning and memory, that they should have little side effects and possess low toxicity. 
By that end, the natural cognitive ingredients we have listed are safe and are tolerable for human consumption, because each one has clinical studies involving humans, rather than just anecdotal internet chatter considered as 'proof'.
In fact, a deficiency of the micronutrients could lead to an impairment of both physical and mental well-being. 
Before you use any natural cognitive ingredient or nootropic product you must ensure that you research the ingredients to ensure they are safe and legal as there is no 'standard' for a dietary supplement.
This means cross-referencing with studies, checking the manufacturer, and ensuring they comply with safety regulations with associated certifications.
Cognitive Impairment Causes
We have looked at the options for cognitive impairment, and the prescription drugs available plus the natural vitamins, minerals, amino acids and herbal extracts that also have clinical proof that they can help improve a number of parameters.
What are the causes of cognitive impairment?
There are established medical diagnoses for disease-related cognitive issues. The University Hospital Southampton list a number of conditions that they treat. 
- Alzheimer's disease
- Behavioral arient frontotemporal dementia
- Corticobasal degeneration
- Huntington's disease
- Lewy body dementia
- Mild cognitive impairment
- Primary progressive aphasia
- Progressive supranuclear palsy
- Vascular dementia
Some of the conditions do not have an obvious cause.
Whereas others can be attributed to poor blood flow due to damaged blood vessels in the brain, abnormal clumps of proteins, damage to brain lobes, other brain disorders or even being hereditary.
However, sometimes we have 'senior' moments and suffer from 'brain fog' – periods of forgetfulness, misjudgment with a lack of focus and concentration.
With this, sometimes there is a much simpler cause that can be easily rectified.
The Harvard Medical School has published a guide to help ward off potential cognitive decline. 
Thankfully these are simple, and can easily be incorporated into your daily life.
Let's take a look at what they suggest:
- Mental stimulation
Let's take a look at each one individually.
Cognition and exercise
Physical exercise is lauded with being a gene modulator that can help produce functional and functional brain changes which help with cognitive functioning and well-being.
Exercise is also recommended to help reduce neurodegeneration. 
Cognitive effects of sleep deprivation
We have mentioned in another one of our articles that a lack of sleep can have a negative effect on cognitive function amongst other areas of your general health.
It has been observed by a published report in the Neuropsychiatric Disease and Treatment journal that sleep deprivation affects memory, attention, and decision making. 
Alcohol and cognitive decline
There is evidence that even moderate alcohol consumption is detrimental to brain health. 
While it is often speculated that 'moderate' drinking is not a risk, quantities or timescales and the risk of cognitive decline is not always agreed upon. 
However, the Journal of Public Health concludes that drinking more than one (UK) standard unit of alcohol does have a negative effect which is then more evident in older people. 
Why is mental stimulation important?
Like physical exercise, mental exercise is good for the brain. Simple tasks such as crossword puzzles, reading, or using mental arithmetic are all recommended by governing and health bodies to improve and maintain cognitive health. 
Social interaction and cognitive development
In a study involving over 1100 people, it was discovered that those who were more socially active suffered from less cognitive decline.
In fact, those who were socially active saw up to a decrease of 47% of cognitive decline compared to those who were less sociable. 
Diet and cognition
Nutrition and diet play an important role in cognitive health.
Highly nutritious foods, typical of a Mediterranean diet, are associated with less cognitive decline, and diseases such as dementia or Alzheimer's. 
Diet for Cognitive Health
It was covered within the 'Cognitive Ingredients' section that the body requires a number of vitamins and minerals to function optimally.
This also includes cognitive function.
Where possible, you should always seek to ensure that you fulfill your micronutrient requirements from a variety of food sources, because, your body cannot produce them itself. 
A lack of nutritional food sources can lead to malnutrition.
UNICEF states that malnutrition is responsible for the majority cases of ill-health with every country across the globe being affected in one way or another.
Furthermore, there are high incidences of iron and vitamin A deficiencies across the world, two micronutrients that are included in MilitaryMuscle to help ensure you are topped up  with an iron deficiency having a particularly negative effect on cognition and motor skills. 
Therefore, foods such as eggs, beef liver, fish, cheese, butter, carrots, spinach, pumpkin, and sweet potatoes are great for vitamin A.
For iron intake, red meats, poultry, eggs, green vegetables, and fruits are great sources.
Low levels of zinc have also been identified as a major health issue, with some studies available that demonstrate superior neuropsychological performance associated with zinc supplementation. 
As with iron and vitamin A, foods such as red meat, seafood, poultry, and nuts are ideal.
Varied Nutritional Sources
It may come as no surprise to learn that a diet high in green vegetables and lean meats is associated with fewer instances of cognitive decline, dementia, or Alzheimer's disease. This is known as the Mediterranean diet. 
This is because a mainly plant-based diet includes many antioxidants that combat oxidative stress which can protect the brain while also being high in Omega-3 polyunsaturated fatty acids from seafood sources such as salmon and oysters. 
These Omega-3 fats are important because they help with brain development and studies have found they can help reduce the risk of cognitive impairment. 
The Mediterranean diet also includes olive oil. It is known that extra olive oil includes nutrients like vitamin K and E but also high amounts of oleic acid which can reduce inflammation and contains antioxidants. 
Cognitive performance and dehydration
Whilst there is a lot of talk about nutrients, we often forget about water.
Water is extremely important, and like sleep, if we do not get enough of it, it can impair our cognitive functioning.
There's lots of information available that declares the brain is about 75% water, therefore, let's not become dehydrated as this can have a negative impact on the way it operates. 
This is especially true when we learn that water helps dissolve vitamins and minerals so the body can utilize them effectively.
In addition, water also carries nutrients and oxygen to cells. 
Studies into the effect of dehydration have noted that lots of people are unaware of their own hydration requirements which can lead to sustained dehydration. 
A study initially published in 1987 looked into how heat and dehydration would affect the mental performance of eleven subjects who were in the tropics.
Even with just 2% body dehydration, the subjects displayed a significant decline in mental functioning. 
It has been concluded by a group of researchers from the University of Reading (UK) that dehydration does cause cognitive defects whilst causing mood disturbances.
They also discovered that hydration can improve mood and visual attention. 
The recent knowledge regarding hydration, its positive effects on bodily and cognitive function has led the European Food Safety Authority to set guidelines between 2000 and 2500ml of water to be consumed.  
Military and Cognitive Studies
It has been established that an iron deficiency has a negative effect on physical and cognitive performance for female soldiers during basic training.
Studies have found that mood is increased as were running times for those who received an iron supplement of 100mg. 
The US Army Medical Journal reports that there is a direct link between nutrition, sleep, and activity.
They call it the 'Performance Triad'.
Their study identifies that sleep quality has an impact on nutrition and cognitive function, whereas nutrition affects sleep, recovery, fatigue, physical and cognitive performance.
The third link is that physical activity and fitness affect the other parameters such as cognitive function, mood, social health, and appetite mechanisms.
If one link is broken, it will essentially collapse the structure meaning all of the other parameters can be negatively impacted.
The study concluded that those who consumed a healthy diet, whilst drinking lots of water, used nutritional supplements, and regularly exercised were associated with all dimensions of health, physical fitness, and psychosocial status. 
In this article, we wanted to explore the intrinsic link between nutrition and cognitive function.
We discovered that there is a rate of cognitive impairment across the globe due to an aging population.
It was then established that people have a desire to better themselves, improve their performance, and become more competitive.
This desire is often chased through the use of prescription drugs, regardless of whether there is a genuine (legal) need or not.
With prescription drugs come a higher level of risk, especially if misused, in this case, we mean without an accompanying prescription from a medical professional.
However, there are compounds from varying vitamins, minerals, and botanical sources that are proven to help increase all the parameters of cognitive function and help reduce the risk of developing diseases such as Alzheimer's, Parkinson's, and dementia.
These, in a perfect world, should be sourced predominantly from our diet, essentially the food we eat, notwithstanding the importance of staying hydrated, yet we can also fill any gaps or deficiencies with nutritional supplements. 
Military studies concluded that there is a solid link between those who perform the best both physically and mentally with nutrition, sleep, hydration plus physical exercise.
What we conclude, supported with evidence, that nutrition is merely an intrinsic cog in a large machine that affects numerous functions. 
Yet, without a healthy, varied diet of nutritious foods, other plant sources, and water we have found that it will have a detrimental impact on cognitive health and function.