Methylphenidate was accepted into medical practice in 1960 as a way to treat narcolepsy and ADHD. It works by inhibiting the reuptake of dopamine and norepinephrine into the nervous system, causing a flooding of dopamine and norepinephrine in the synapse between the nerves, which in turn leads to amplified signaling between neurons. It’s been said that these effects are basically the same as those of amphetamines (see more details below), which are synthetic, addictive, mood-altering drugs, used illegally in sports as a stimulant and also legally as a prescription drug – like Ritalin – to treat children with ADD and adults with narcolepsy.
Amongst the brain focus supplements that are currently available in the nootropic drug market, Modafinil is probably the most common focus drug used by people, and it’s actually touted to be the best nootropic available today.  It is a powerful cognitive enhancer that is great for boosting your overall alertness with least side effects.  However, to get your hands on this drug, you require a prescription.
It can easily pass through the blood-brain barrier, and is known to protect the nerve tissues present in the brain. There is evidence that the acid plays an instrumental role in preventing strokes in adults by decreasing the number of free radicals in the body.  It increases the production of acetylcholine , a neurotransmitter that most Alzheimer’s patients are deficit in.
Cognizin– this is a derivative of citicoline. It increases* the levels of acetylcholine neurotransmitters, dopamine, and noradrenaline in the brain. These are neurotransmitters essential for brain functioning. Besides this, Cognizin maintains the functioning and stamina of neuronal cell membranes and enhance* energy production from the frontal cortex. With this, you will have increased mental reaction time, expanded focusing ability, improved* immediate and short-term verbal memory and augment the brain’s metabolism.
Alex's sense of who uses stimulants for so-called "non-medical" purposes is borne out by two dozen or so scientific studies. In 2005 a team led by Sean Esteban McCabe, a professor at the University of Michigan, reported that in the previous year 4.1% of American undergraduates had taken prescription stimulants for off-label use - at one school the figure was 25%, while a 2002 study at a small college found that more than 35% of the students had used prescription stimulants non-medically in the previous year.
Piracetam is used to increase memory, learning, and concentration. It is not reported to be toxic even at high doses, but healthy people are reported to not get that much of a boost from it, and it is understood to be most effective for older people. It’s been found to reduce the chances of a breath-holding spell in children, enhance cellular membrane fluidity, and prevent blood clotting on par with aspirin.

There are many studies that suggest that Creatine helps in treating cognitive decline in individuals when combined with other therapies. It also helps people suffering from Parkinsons and Huntingtons disease. Though there are minimal side effects associated with creatine, pretty much like any nootropic, it is not  absolutely free of side-effects. An overdose of creatine can lead to gastrointestinal issues, weight gain, stress and anxiety.
The use of cognition-enhancing drugs by healthy individuals in the absence of a medical indication spans numerous controversial issues, including the ethics and fairness of their use, concerns over adverse effects, and the diversion of prescription drugs for nonmedical uses, among others.[1][2] Nonetheless, the international sales of cognition-enhancing supplements exceeded US$1 billion in 2015 when global demand for these compounds grew.[3]