**6. Perspectives**

performance in patients with mild to moderate AD, when compared with placebo [95]. However, diverse studies conducted in healthy volunteers have showed that AChEIs lightly improve verbal memory after semantic processing of words, attention memory, information

Memantine is a psychostimulant used to treat moderate to severe AD. It acts on the glutamatergic system by antagonizing N-methyl-d-aspartate (NMDA) receptors. This drug has been showed to slightly improve cognitive functions as monotherapy of AD [97]. There are few studies about the cognitive-enhancing capacity of memantine on healthy volunteers. The studies published were tested with acute single dose of memantine, finding that this drug

Modafinil is a psychostimulant indicated in the treatment of narcolepsy, shift work sleep disorder and excessive daytime sleepiness [98]. Since approval by FDA, in 1998, modafinil has been widely used not only to treat wakefulness disorders, but also to increase alertness and enhance cognition. Modafinil exhibits advantages among other psychostimulants, including the lack of unwanted side effects (e.g., tolerance, abuse potential, sleep rebound and locomotor excitability) [99], and, in most countries, it is not a controlled substance; therefore, it can be easily purchased online. Modafinil exerts its actions through an unknown mechanism. Still, it is recognized that modafinil inhibits dopamine and noradrenaline uptake, elevates catecholamine's levels, therefore raises extracellular serotonin, glutamate, histamine and orexin and reduces GABA's concentration [100]. Although the effects of modafinil as a wakefulness promoter have been proven [101], its properties as cognitive enhancer are still controversial. In sleep-deprived individuals, modafinil improves attention, memory and executive function [102], while the effects of modafinil in non–sleep-deprived adolescents are limited [103]. Other reports have found that modafinil actually improves several cognitive functions [104]. Interestingly, modafinil has showed to enhance mental performance of subjects with low

MPH (Ritalin©) is a psychostimulant approved for the treatment of attention deficit/hyperactivity disorder (ADD/ADHD) [106]. Additionally, MPH is one of the most effective cognitive enhancers used by healthy people [107], because it acts through a mechanism analogous to that of cocaine: increases the levels of the catecholamines, dopamine, norepinephrine and serotonin, by blocking their transport [108]. This drug improves working memory, speed of processing, verbal learning and memory and attention [102]. Nevertheless, MPH effects are not restricted to spatial problems, since it also improves digit span test score [109]. Although MPH has demonstrated to be effective and safe in most of the patients when used in the short term, several side effects have been reported: decrease of appetite, insomnia, headache, irritability, weight loss, sadness, abdominal pain, nausea, somnolence, dizziness, among others.

processing, executive function and memory mood [96].

does not increase mental performance significantly [96].

baseline performance or IQ on several tasks evaluated [105].

**5.3. Methylphenidate (MPH)**

*5.1.2. Memantine*

70 Health and Academic Achievement

**5.2. Modafinil**

Drug abuse and addiction to legal and illegal substances have become a major challenge in western developed and developing societies. Growing evidence has shown that the onset age of drug consumption is around 15 years. At this age, the central nervous system is still under maturation. Childhood and adolescence are critical stages for neural and social development. Therefore, worldwide increasing prevalence of drug abuse among teenagers will certainly have an effect on scholar performance. All the evidence described in the present review suggests that teenagers that consume drugs risk deleterious consequences in their academic growth, since the neural mechanisms targeted by these drugs may have long-term impacts on cognitive functions. Therefore, prevention initiatives and public health programs must be implemented in schools to protect children and teenagers from escalating drug use.
