Short communicationIncreased electroencephalographic activity in crack-cocaine users visualizing crack cues
Introduction
A growing amount of evidence suggests that electroencephalographic activity increases when cocaine users are exposed to pictures of cocaine compared to neutral images (Bauer and Kranzler, 1994, van de Laar et al., 2004, Dunning et al., 2011). Functional magnetic resonance imaging (fMRI) analyses showed a significant increase in the activation of prefrontal, limbic and parietal lobe brain regions of cocaine users as the cocaine cues were being viewed (Garavan et al., 2000a). Studies on other drugs of abuse also reported electroencephalographic activity changes related to cognitive dysfunction reinforcing the ERP as a relevant tool in psychiatry (Oscar-Berman, 1987, De Cesarei et al., 2006, Petit et al., 2015).
The event-related potential (ERP) has emerged as an important technique to study the cognitive potentials underlying the presentation of a stimulus (i.e., cue) (Brandeis and Lehmann, 1986, Picton et al., 2000). Using scalp surface electrodes, neural activity can be recorded in response to a variety of sensory stimuli, and much information can be obtained from these electrodes after a given task. The ERPs consist of a series of waves or components with positive and negative voltage deflections that can be named numerically or according to their latency, where the letters “P” or “N” are traditionally used to indicate positive-going and negative-going peaks, respectively. The first peaks after averaging the stimuli are indicative of an exogenous sensory response that is influenced mainly by stimulus parameters. These peaks are followed by later or endogenous ERP components that have been considered to be associated with cognitive processes (Luck, 2005).
Here, we examined the electroencephalographic activity of crack-cocaine abusers during the cue-reactivity paradigm. All data were compared to healthy control subjects with the hypothesis that crack-dependent individuals are sensitized for crack-related cues.
Section snippets
Subjects
This study included eighteen male participants: nine healthy male control subjects (aged 25.2 ± 4.2 SD) and nine male crack-cocaine users (aged 30.4 ± 5.6 SD). The inclusion criteria for this study were: (1) patients between the age of 18 and 60 years; (2) met criteria for crack-cocaine dependence according to the Diagnostic and Statistical Manual of Mental Disorders, fourth edition, as determined by clinical evaluation; (3) no more than 31 days of abstinence; and (4) in stable clinical
Results
The sample of crack-cocaine users consisted of patients with 5.3 ± 2.7 years of drug use and no more than one month of abstinence (13 ± 10.3 days) and 51.6 ± 46.1 rocks smoked per week. The Electroencephalographic data were obtained in the whole brain through a 32-channel system according to Fig. 1.
The scalp topography clearly shows that the difference between crack-related and neutral image activity was greater in crack-cocaine users group compared wit control healthy subjects (Fig. 2A).
Discussion
In this brief data, we observed that crack-cocaine users are more likely to show higher brain activity measured electroencephalographically, notably in the frontal lobe region, when processing crack-related images.
Cocaine dependence has been frequently associated with low activation in the frontal, parietal and temporal cortical regions, especially during conditions requiring high cognitive control, such as in decision making (Barros-Loscertales et al., 2011). Such conditions may lead
Declaration of interest
The authors have no conflict of interest to declare.
Role of funding source
Equipment and softwares were acquired with financial support by Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq).
Contributors
There are no contributors to declare.
Acknowledgement
We thank all patients and participants. This work was supported by Conselho Nacional de Desenvolvimento Científico e Tecnológico.
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