Original Investigation

Psychopharmacology

, Volume 190, Issue 4, pp 517-530

Profile of executive deficits in cocaine and heroin polysubstance users: common and differential effects on separate executive components

  • Antonio Verdejo-GarcíaAffiliated withDepartment Personalidad, Evaluación y Tratamiento Psicológico, Universidad de GranadaInstitute of Neurosciences F. Olóriz, Universidad de Granada Email author 
  • , Miguel Pérez-GarcíaAffiliated withDepartment Personalidad, Evaluación y Tratamiento Psicológico, Universidad de GranadaInstitute of Neurosciences F. Olóriz, Universidad de Granada

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Abstract

Objectives

Structure of executive function was examined and we contrasted performance of substance dependent individuals (polysubstance users) and control participants on neuropsychological measures assessing the different executive components obtained. Additionally, we contrasted performance of polysubstance users with preference for cocaine vs heroin and controls to explore possible differential effects of the main substance abused on executive impairment.

Methods

Two groups of participants were recruited: abstinent polysubstance users and controls. Polysubstance users were further subdivided based on their drug of choice (cocaine vs heroin). We administered to all participants a comprehensive protocol of executive measures, including tests of fluency, working memory, reasoning, inhibitory control, flexibility, and decision making.

Results

Consistent with previous models, the principal component analysis showed that executive functions are organized into four separate components, three of them previously described: updating, inhibition, and shifting; and a fourth component of decision making. Abstinent polysubstance users had clinically significant impairments on measures assessing these four executive components (with effect sizes ranging from 0.5 to 2.2). Cocaine polysubstance users had more severe impairments than heroin users and controls on measures of inhibition (Stroop) and shifting (go/no go and category test). Greater severity of drug use predicted poorer performance on updating measures.

Conclusion

Executive functions can be fractionated into four relatively independent components. Chronic drug use is associated with widespread impairment of these four executive components, with cocaine use inducing more severe deficits on inhibition and shifting. These findings show both common and differential effects of two widely used drugs on different executive components.

Keywords

Updating Inhibition Shifting Decision making Cocaine Opiates