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Introduction
The idea of using any substance to enhance alertness or cognitive performance in healthy people is very attractive. Since decades ago, people have been using distinct drugs with this purpose, however, recently, their use in teenagers and young adults has gained a lot of popularity1. Central nervous system stimulant drugs (SDs) are all neuroactive substances that increase certain brain neurotransmitters, in particular catecholamines (noradrenaline, dopamine, and adrenaline), although, they can increase other neurotransmitters too like serotonin, histamine, and glutamate1,2. Stimulants are a diverse group of substances that include from natural molecules like caffeine, to a synthetic drug such as methylphenidate, modafinil or amphetamine, and its derivatives3.
There are a lot of publications about possible positive effects with the use of SD in alertness or cognitive functions in healthy people, however, to the date, there is no consensus about its utility as the positive observed effects continue being marginal or inconsistent between studies4. In spite of the lack of evidence on positive effects, its use has increased in the last years in healthy young individuals, particularly in college students5,6.
In addition to the lack of evidence on its positive effects on cognition, there is a certain concern about the safety and risk of addiction to SD with repeated or chronic use7. Furthermore, there is an increasing controversy on the bioethical aspects related to the undiscriminated use of SD on healthy individuals, as is still in discussion if its use should be regularized by health authorities or if it should be considered a form of fraud or brain doping that must be prohibited in educational institutions and other areas8.
There are a great number of studies that explore the frequency of use of SD and risk factors related in healthy individuals, however, comparatively, there are few studies that have explored the public opinion on it use and regulation9,10. On this matter, one study that conducted three surveys in 1400 individuals about their opinion on SD use showed that its acceptance is greater when it is reflected in other person, and also acceptance depended on the context of the use by each study11. Another study performed only in medicine students regarding the use of methylphenidate showed that more than 70% had the perception that methylphenidate could increase their cognitive performance, however, 66% of them were worried with the legality of its use and more than 90% thought that it could be dangerous for their health12. On the other hand, a study conducted by specialists of different medical-biological and social areas showed that depending on the profession, there is great variability on the opinion about the legality of its use13.
Finally, although there are some studies about the frequency of use of SD in Latin America, to the best of our knowledge, there are no prior studies about the general opinion of the use of SD in this population, therefore, the objective of the present study was to get to know the opinion and frequency of the use of SD in a sample of open population in Mexico.
Method
Survey
A clinical transversal descriptive and analytic study was developed. Furthermore, an anonymous survey in an electronic format was developed, in first instance, the survey was applied in pilot group of 50 persons to evaluate the performance and reliability of each question and its adequate understanding by participants; after applying the necessary adjustments, the final version of the survey included 11 multiple-choice questions: six dichotomic answer questions (yes/no) and five with four possible responses, in addition to demographic information and other variables of the participants (sex, age, scholarship, religion, birthplace, chronic diseases, etc.), Questions explored if participants had prior knowledge on SD, if they have used any substances to enhance alertness (like caffeine or tobacco) or to enhance the cognitive functions, as well as their opinion on their safety, if these drugs should be regulated by health authorities, if they are in favor of further research, and finally, a hypothetical scenario was presented on the use of SD: where an individual uses a SD during a job examination and apparently this gives him and advantage over the other applicants obtaining at the end the job in dispute. In this context, the participant was asked if he/she considers the situation fair or unfair and why he/she thinks the individual in the scenario got the job. These two questions have the purpose to discover their opinion on the situation from the ethical perspective.
Participants
The application of the survey had place from August 3 to November 5 of 2021. The link for the survey was sent electronically and the invitation was spread by social media to any person who accepted to answer the survey completely, the inclusion criteria were as follows: people over 18 years old, of any gender and residence place. The only exclusion criteria considered were uncompleted or repeated registered surveys. As the survey was conducted completely anonymous and no confidential information of the participants was managed, the authorization for inclusion in study was requested electronically only.
A more detailed description of the method used in the development and application of the survey is presented in table 1, following the recommendations of the Checklist for Reporting Results of Internet E-Surveys (CHERRIES)14.
Table 1 Summary of Checklist for Reporting Results of Internet E-Surveys (CHERRIES)
| CHERRIE (Checklist Items) | Description |
|---|---|
| 1. Design of survey | Target population: open population, adults over 18 years of age, of both sexes. Convenience sample. |
| 2. Institutional Review Board | Research project was approved by the bioethics committee of the National Institute of Rehabilitation LGII, with registration number 54/17. The survey was conducted completely anonymous and no confidential information of the participants was managed; the informed consent for inclusion was requested in electronic format. Digital information was encrypted to guarantee confidentiality and to prevent unauthorized access. |
| 3. Development and pre-test | Survey was developed by clinical neuroscience research experts and in first instance was applied in pilot group of 50 participants to evaluate the performance and reliability of each question. |
| 4.Recruitment process and description of the sample having access to the questionnaire | Link for the survey (Google Forms) was sent electronically and the invitation was spread by social media in person-to-person manner, to any person who accepted to answer the survey completely, the inclusion criteria were people over 18 years old, of any gender and any residence place. |
| 5.Survey administration | Invitation was made by social networks (WhatsApp or Facebook), participation was completely voluntary; there was no randomization in the questions; the final version included 11 multiple-choice questions: six dichotomic answer questions (yes/no) and five with four possible responses, in addition to demographic information and other variables of the participants (sex, age, scholarship, religion, birthplace, chronic diseases, etc.). Survey was applied between August 3 and November 5 of 2021. |
| 6. Response rates | The electronic format of the survey could only be answered once, and no question could be left unanswered. No estimate of the percentage of participation was made. |
| 7. Preventing multiple entries from the same individual | The survey was linked to a valid email address and could only be answered once per email address. |
| 8. Analysis | Only fully answered surveys were analyzed; there was no limit of time to complete the survey and no weighting was done within the questions of the questionnaire. |
Statistical analysis
The data were concentrated in a database, and in first term, descriptive statistic was used with mean, median and range to present the general characteristics of the population; in second term, a Fisher’s exact test and/or a Chi-square test were used to evaluate the association between the prior use of SD and the participants demographic variables. For the analysis, the GraphPad Prism software version 6.0 was used. p < 0.05 was considered statistically significant.
Results
There were a total of 526 opinion surveys completed. Two hundred and seventy-one participants were male (51.5%) and 249 females (47.3%), the rest did not specify (6 = 1.1%). The average age of all participants was 29 years old (± 14 years). The age groups distribution was as follows: 18-20 years old: 187 (35.5%); 21-30 years old: 192 (26.5%); 31-40 years old: 46 (8.7%); 41-50 years old: 46 (8.7%); and 51-85 years old: 55 (10.4%). The average scholarship in total sample was 12.7 years (± 2.29 years), the distribution by school grade was as follows: elementary and middle school concluded: 47 (8.9%); high school concluded: 306 (58.1%); university concluded: 151 (28.7%); and masters or PhD: 22 (4.1%). On religion, the most frequent one was catholic in 289 participants (54.9%), other religion: 63 (11.9%), and none in 174 (33%). About place of residence, the majority was from Sinaloa (n = 264, 50.1%), 126 from Mexico City or Estado de Mexico (23.5%), and other federal entities 135 (26.6%). About their occupation: 261 were students (49.6%), workers from health areas: 41 (7.7%), other jobs: 169 (32.1%), and unemployed: 55 (10.4%). On chronic diseases, 470 (89.3%) did not suffer any chronic disease and 56 (10.6%) did.
About the prior knowledge on SD, 75.6% of participants answered yes and 24.3% answered no. On the prior use of SDs, 72 (13.6%) participants responded yes, 37 of them were male and 35 were female, from the 72 participants that answered yes, only 37 (51.3%) of them used a drug that actually possesses stimulant properties (examples: methylphenidate, Adderall, modafinil, atomoxetine, armodafinil, nicotine, and caffeine), and 38.8% mentioned used other types of drugs or substances that are not considered stimulants (examples: multivitamins, antidepressants, melatonin, and anxiolytics). On the other hand, 79% of participants (n = 416) confirmed their use of any substance (caffeine, tobacco, energy drinks, etc.) to maintain or enhance their alertness. Of them 30% (n = 125) consume it daily, 20.4% (n = 85) use it from 1 to 3 times/week and 49.5% (n = 206) consume it sporadically, 63.3% (n = 333) said “I don’t know” and 10.2% (n = 54) don’t answered. In the question, where participants were asked if they considered that SD should be controlled by health authorities: 463 (88%) answered positively. Finally, in the hypothetical scenario, 153 (29%) considered the scenario as “fair;” 76 (14.4%) mentioned that the situation was “unfair” and 227 (63.8%) gave other responses. On the same hypothetical scenario, 54 (10.2%) participants attribute the success of person in hypothetical scenario to the use of SD and 63.8% (n = 336) attribute it to other causes different from the SD.
When performing the analysis of association of variables, three variables associated significantly with prior SD use, the age group between 18 and 30 years old (p = 0.0376), scholarship above high school (p = 0.0493), and practicing a religion different from catholic or have no religion (p = 0.0041).
Discussion
The use of SD for different purposes has been popularized in the past few years, particularly in young and healthy individuals, however, it is difficult to establish exact reliable prevalence as there are many variables that influence the results of the studies2.
In this sense, one of the aspects that limit the veracity of surveys is that the use of SD can be seen as something forbidden, dishonest, or unethical, therefore, many people usually do not tell the truth about it15. For this reason, results very important to know the opinion and attitudes of the general population toward SD use in healthy subjects. To the best of our knowledge, this is the first opinion survey on this theme conducted in our country.
In the present survey, one of the aspects to highlight about the studied population characteristics is that the majority of participants were young with an average age of 39 years old which could be due to different factors, being the most probable the easy access to electronic social media, which was the way by the survey was spread in all the age groups16. In relation to the youth of the population, we also found a very small percentage of participants with chronic diseases (10.6%). In addition, other aspect to highlight is that the education level of the included sample was high with an average of 12.7 years, which is higher that general average scholarship reported in Mexico, being it the highest in Mexico city with 12 years, and the lower in Chiapas with 8 years17. This could be due to the same reason that was previously indicated and also the fact that the great majority of our individuals were students or have a job.
About the participants responses, there was a high prevalence of previous knowledge about SD (75.6%), which could be due to the high scholarship and age of the participants, which is precisely the population where these drugs are the most popular1,2. On the other hand, in spite of the high frequency of knowledge about SD, the frequency of prior use of SD for cognition was only 13.6%, however, it is difficult to contrast this number with other studies as there is a great variability in the reported prevalence, which range from 1% to 20%18. The reasons for this variability are diverse, from the way, the surveys are conducted (anonymous, electronically, personally, etc.), the type of population studied (university students, professionals, open population, etc.), the definition of SD used, if it refers to current or previous use, if it includes the medical prescription of SD, etc.3. Other important factor to consider is that not every participant has the same concept of what is considered a SD, as the 72 participants that confirmed prior use of them, only 37 (44%) were actually using a drug that is considered a stimulant, which means that more than half of the participants attribute stimulant properties to other substances being the most common the vitamin supplements; this is highly related with the extended myth that vitamins have positive effects in alertness, energy, vitality, or even enhance the appetite19. In contrast, results interesting that 79% of individuals reported using any substance to increase or maintain alertness, being caffeine the most popular. This highlights the fact that the knowledge of “stimulant” concept is ambiguous in general population, as many people consume coffee or nicotine (both considered stimulants) as part of their daily life without pretending necessarily a specific stimulant effect20. About the opinion on the safety of SD, most participants said that they could result dangerous (most think that only in excess), this opinion coincide well with previous studies that point a latent concern in users and non-users on security and risk of addiction to these drugs21. However, some recent clinic studies have only showed adverse effects with the moderate use of these drugs22. On the other hand, most participants (88%) confirmed to believe necessary the control and regulation of SD by health authorities, this could be due to the possible risks and ethical dilemmas that have been related to its use21. In practice, the majority of these drugs are sold only with medical prescription, there are some of them without this regulation like modafinil in Mexico. In spite of these concerns on the use of SD, the great majority of participants (89%), they were in favor of promote the research to develop SD more effective and safer; on this matter, we did not find other prior survey that explored the same issue, but it is possible that because the majority of the participants are young students, they are more in favor of further research son these drugs. About the ethical-hypothetical scenario presented, it is interesting that 30% considered the situation fair, however, almost 64% considered that the benefits were not related with the use of the drug. This suggests that apparently not all participants are convinced that SDs have significant effects increasing the cognitive performance in real life23. Finally, the association analysis showed that the age group between 18 and 30 years old, a scholarship above high school, and the practice of a religion different to Catholicism or non-practicing any religion were related factors with the prior use of SD. This profile of young high school or university students is the same profile that is related with the use of SD in the most previous studies, whereby it matches well with the reported in international literature2,18. About religion, other authors have observed similar results, where the religious environment tends to associate to less use of stimulant substances, even more if they are illegal drugs24. In another similar study carried out in a rural population, it was observed that religiosity was related to a lower propensity to consume illicit drugs such as cocaine and methamphetamine25.
To finalize, it is very important to highlight the identified limitations and biases in the present study, being the most important the electronic distribution of the survey in social media that can sometimes be reached only by a small part of the open population (mostly young people), whereby this study cannot be totally representative of the opinion in the general population, as it was discussed before this could influence both the frequency of use and the opinions on SD; thus, in the future, it will be necessary to develop more extensive similar surveys including population above 50 years old, with more diverse levels of education and socioeconomic status to be able to have a more general vision on the use and opinion about SD in healthy subjects.
Conclusion
In the present electronic anonymous survey, whose majority of participants were young adults, mainly students, a prevalence of the use of SD was 13.6%, with a frequency of 80% of the use of stimulants for alertness. Majority of participants have doubts on the safety of the stimulants, are in favor of their regulation by health authorities, but are in favor of continuing with further research on this type of drugs. Finally, the use of stimulants was associated with the age between 18 and 30 years old, a scholarship over high school and the absence of religious beliefs.
