This study showed that the consumption of illicit drugs was higher in young drivers, smokers, and those who frequently consumed alcohol and who had a higher average number of daily driving hours. The prevalence of the use of illicit drugs and alcohol consumption found in the present study is within the average found in the literature for studies based on reports by truck drivers.9 The percentages of consumption of amphetamine, marijuana and cocaine vary from 0.9% to 70%, 0.2 to 29.9% and 0.1% to 8.3%, respectively. This great variation between study results is probably due to methodological differences, sample variations and different geographic regions in which the research was carried out.
Amphetamine, known as “rebite” among Brazilian drivers, is used mainly as a stimulant to combat tiredness10, as its main effects are increased alertness, decreased fatigue, elevated mood, euphoria and increased motor activity27-29. In Brazil, due to side effects, the potential to cause addiction and the tendency toward indiscriminate use,
the sale, production and prescription of the substance has become prohibited in accordance with resolution RDC 52/201130,31. However, amid controversies among doctors and health agents, in 2017, a bill was approved for them to be produced, marketed and consumed under prescription again32.
Leyton and colleagues point out that the legislation may have caused a change in consumption patterns of amphetamine stimulants during the years in which it was in effect.33 Between 2009 and 2016, the analysis of 4,110 biological samples from drivers also showed an increase, although not statistically significant, in cocaine consumption. Amphetamine use changed over the years, with high consumption in 2010 (8.9%) but a decline in 2011 and 2012 (1.7% to 2.0%), followed by a stable period from 2013 to 2015 (ranging from 2.9% to 4.1%). In this research, it was found that such drugs were mainly used to combat fatigue in long-distance drivers, but the possibility of recreational use in drivers working shorter hours is not ruled out.
During the period of this study (2010 to 2016), although the medication was prohibited, 33.33% of the drivers who declared consumption of other illicit drugs also reported the use of amphetamine as a stimulant. The amount is significantly higher than the 16.38% who reported having used amphetamine stimulants but did not report the use of other illicit drugs. Amphetamines exert peripheral sympathomimetic actions, producing elevated blood pressure, death of cardiac muscle cells, coronary insufficiency, increased heart rate and other cardiovascular changes resulting from increased concentration of norepinephrine in synapses34.
Cocaine acts on the nervous system by inhibiting the reuptake of norepinephrine, dopamine and serotonin through interaction with its transporters, resulting in prolongation and overactivity of the sympathetic nervous system. Another possible effect is the blocking of sodium/potassium channels, causing cardiovascular changes, which may present increased and prolonged risks when there is an association between cocaine and alcohol.17 In a review including a range of studies on the effects of the drug, it was found that its frequent use may be strongly associated with an increased risk of acute cardiovascular complications, such as hypertension, coronary aneurysms, arrhythmias and myocardial infarction16-18.
Cocaine and its metabolites also affect behavior regarding food intake and suppress appetite, which can lead to the disruption of metabolic and neuroendocrine regulation, resulting in an increased risk of developing body weight problems, diabetes and metabolic syndrome17. Studies with humans have also shown anorexigenic effects of cocaine, and the low caloric intake, together with abnormal metabolic and gastrointestinal functions, can lead to malnutrition among drug users17.
In this study, body fat and hypertension were significantly related to the reported consumption of illicit drugs, and the lower percentage of fat for users of illicit drugs is consistent with what was found in the literature, since amphetamine and cocaine have proven effects on metabolic functions and are anorectic agents17,30,34. Although the prevalence of hypertension found among those who declared they had already used illicit drugs (9.8%) was lower than that found among those who had never used illicit drugs (15.2%), it should be considered that this factor may also be directly linked to a low percentage of body fat and the young average age.
According to the Brazilian cardiovascular prevention guidelines (BCPG) 38, SAH is one of the most important risk factors for the development of coronary artery disease, heart failure, cerebral vascular disease, chronic kidney disease and atrial fibrillation.35 The BGPC also show that 22 studies found a prevalence of SAH in the adult population of between 22.3% and 43.9% (average of 32.5%), being higher than the 50% prevalence identified in individuals between 60 and 69 years old and 75% in those over 70 years old; that is, there is a lower occurrence in younger individuals, and there is a visible progressive increase according to age.
Although there is evidence of an association between marijuana use and acute cardiovascular problems, it was not possible to assess the long-term chronic effects of using this drug18. The first study to link ischemic stroke in humans with marijuana use was done in the United States, and even after adjusting for other substances of abuse and eliminating confounding variables, it was found that the association persisted, showing that it is independent of other factors17.
There is evidence that marijuana users who are also smokers are more likely to develop ischemic heart disease, a fact that was also reproduced by Singh and colleagues in a study review36. In view of the increase in drug use and the alarming number of new cardiovascular events related to it in recent decades, it is important to emphasize that there is a need to increase scientific work on this relation that is underestimated and underreported36.
The variable “illicit drugs”, which had a positive association with the independent variables “age”, “smoking”, “alcohol consumption” and “marital status”, provided us with a profile of consumption that showed that younger drivers, with an average age younger than 40 years; singles; and individuals who smoke and consume alcohol are those most likely to use psychoactive substances. In addition, among drivers who reported having consumed substances of this type, the majority, when compared to non-users, had less time in the profession, drove for more hours during the day and traveled longer distances.
Girotto et al reported similar results in truck drivers from the port of Paranagua, concluding that those most susceptible to the use of illicit psychoactive substances were those who were younger, who had irregular working hours, who were single and who normally traveled long distances.15 Additionally, Bombana et al found that drivers who travel in the main highways in the state of São Paulo and consume illicit drugs are younger, have less experience in the profession and have a habit of driving for longer distances.14
Alcohol consumption and smoking were more prevalent among drivers who reported drug use at some point in life37. This is in line with what was previously found in the literature9. In a study carried out in Japan, alcohol appears to be associated with a younger average age, smoking, high blood pressure and a lower average BMI39.
Strengths and weaknesses of the study
This observational cross-sectional study individually estimated the effect of illicit drugs with respect to health and occupational risk factors. Our study used a large and population representative data of truck drivers that allowed a detailed analysis of the association between illicit drugs and demographic and cardiovascular risk factors. Nevertheless, due to its cross-sectional nature, the ability to elucidate causal relationships between the use of illicit drugs and health risk factors is limited.
The scarcity of studies targeting health-related risk factors of truck drivers is a limiting factor for queries and comparisons to be made with other percentages and prevalence values found prior to this research. There is a great need to develop new research in this sector, mainly in Brazil, where the population of truck drivers is large.
Another limitation is the dependence on the reliability of the interviewees' report, who may omit information, especially with regard to drug use. On the other hand, when compared to studies based on toxicological tests, which may underestimate the use of illicit drugs because they only indicate the use of drugs in a short period prior to the examination, studies based on reports may be more comprehensive.