Driving under the influence of psychostimulant drugs: Effects on cognitive functioning among truck drivers in Brazil

Introduction: Brazil has one of the highest traffic accident rates in the world. Cargo vehicles are the second most common type of vehicle involved in these accidents. Driving under the influence of drugs increases the risk of truck drivers being involved in road traffic injuries or fatalities. Psychostimulant drug use among truck drivers is of particular interest, as they use these drugs to maintain their occupational performance. Aim: The aim of this study is to identify the prevalence of psychostimulant drug use among truck drivers through toxicological analyses of urine and saliva samples and to evaluate its effects on the drivers' performance on attention level and executive functioning tests. Methods: A nonprobabilistic sample of 684 truck drivers was recruited at truck stops along three highways in Sao Paulo, Brazil. Participants were requested to answer questions on personal information and work-related matters via a structured research instrument. Afterwards, they were asked to perform four cognitive tests and to complete other questionnaires on confounding variables. Strict exclusion criteria were enforced. Descriptive and inferential analyses were performed in the Minitab 18.1 and R programs, version 3.5.3. Then, the variables from the cognitive performance tests were included as response variables in the generalized linear regression models, separately, correcting for the effects from confounding variables. Results: 504 drivers were excluded from the data analysis due to health conditions that prevented them from safely participating in a cognitive performance evaluation. Therefore, 180 drivers remained in the sample; among them, 44 participants were categorized as users, and 136 were categorized as nonusers. The drug users performed better than the nonusers in almost all the cognitive tests in the univariate analysis. However, after controlling for the effects of confounding variables, we observed that despite drug users being faster at performing some tests, they committed more errors and had lower precision rates than nonusers in other measures. Moreover, users dealt with tasks that involved alternate and divided attention more poorly than nonusers. Conclusion: Psychostimulant drug use may initially seem advantageous to truck drivers since it allows users to maintain their attention for longer periods of time; however, the onus related to that use is much larger and should therefore be avoided by truck drivers and policed by competent authorities. (C) 2019 Elsevier Ltd. All rights reserved.