Cognitive impulsivity in cocaine and heroin polysubstance abusers.
BACKGROUND
Chronic abuse of psychoactive substances produces significant deficits in executive control functions (ECF). These deficits are prominent in different domains associated with cognitive impulsivity, including response inhibition and decision-making. The extent and nature of these deficits may depend on the principal substance of abuse.


OBJECTIVE
To analyse response inhibition and decision-making performance in abstinent polysubstance abusers (PSA) of cocaine and heroin, and healthy participants.


METHODS
We used univariate and multivariate analyses of variance to compare the performances of cocaine and heroin PSA and healthy controls on several well-validated measures of response inhibition (Stroop, 5-Digit Test and Go/No Go Task) and decision-making (Iowa Gambling Task). Post-hoc exploratory analyses of the results from the Go/No Go task were conducted to examine specific effects of task switching on the pattern of omission/commission errors in the PSA groups.


RESULTS
Cocaine but not heroin PSA showed significant deficits on several measures of response inhibition, when compared to controls. Reversal of task contingencies in the Go/No Go task primarily altered the commission error rate in cocaine PSA, and the omission error rate in heroin PSA. In contrast, both cocaine and heroin PSA showed poorer performance on decision-making compared to controls.


CONCLUSIONS
Assuming the relevance of polysubstance involvement, cocaine abuse seems to differentially correlate with motor impulsivity skills, while both substances seem to be equally linked to the inability to decide advantageously in complex decision-making tasks. Possible discrepancies in the neurological and psychological effects of these drugs are discussed.
Verdejo-García
Antonio J
AJ
Dept. Personalidad, Evaluación y Tratamiento Psicológico, Universidad de Granada, Campus de Cartuja, s/n, 18071 Granada, Spain. averdejo@ugr.es
Perales
José C
JC
Pérez-García
Miguel
M
D000328:Adult; D000704:Analysis of Variance; D019970:Cocaine-Related Disorders / Q000523:psychology*; D003071:Cognition; D003657:Decision Making; D006556:Heroin Dependence / Q000523:psychology*; D006801:Humans; D007175:Impulsive Behavior / Q000523:psychology*; D007266:Inhibition, Psychological; D009483:Neuropsychological Tests; D011597:Psychomotor Performance; D011930:Reaction Time