Elizabeth C. Long, Radka Kaneva, Georgi Vasilev, F. Gerard Moeller and Jasmin Vassileva* Pages 586 - 598 ( 13 )
Background: The differential utility of neurocognitive impulsivity and externalizing/ internalizing traits as putative endophenotypes for dependence on heroin vs. amphetamine is unclear.Objective: This exploratory study aims to determine: (1) whether neurocognitive impulsivity dimensions and externalizing/internalizing traits are correlated between siblings discordant for heroin and amphetamine dependence; and (2) which of these associations are common across substances and which are substance- specific. Methods: Pearson correlations between individuals with ‘pure’ heroin and amphetamine dependence and their unaffected biological siblings (n = 37 heroin sibling pairs; n = 30 amphetamine sibling pairs) were run on 10 neurocognitive measures, 6 externalizing measures, and 5 internalizing measures. Sibling pair effects were further examined using regression. Results: Siblings discordant for heroin dependence were significantly correlated with delay aversion on the Cambridge Gambling Task, risk-taking on the Balloon Analogue Risk Task, sensation seeking, and hopelessness. Siblings discordant for amphetamine dependence were significantly correlated on the quality of decision-making on the Cambridge Gambling Task, discriminability on the Immediate Memory Task, commission errors on the Go/No Go Task, trait impulsivity, ADHD and anxiety sensitivity. Conclusion: Dimensions of impulsivity and externalizing/internalizing traits appear to aggregate among siblings discordant for substance dependence. Risk-taking propensity, sensation seeking and hopelessness were specific for heroin sibling pairs. Motor/action impulsivity, trait impulsivity, and anxiety sensitivity were specific to amphetamine sibling pairs. Decisional/choice impulsivity was common across both heroin and amphetamine sibling pairs. These findings provide preliminary evidence for the utility of neurocognitive impulsivity and externalizing/ internalizing traits as candidate endophenotypes for substance dependence in general and for substance-specific dependencies.
Addiction, Impulsivity, Externalizing, Internalizing, Endophenotypes, Discordant siblings.
Edna Bennett Pierce Prevention Research Center, Pennsylvania State University, University Park, PA, Department of Medical Chemistry and Biochemistry, Sofia Medical University, Sofia, Bulgarian Addictions Institute, Sofia, Institute for Drug and Alcohol Studies, Virginia Commonwealth University, Richmond, VA, Institute for Drug and Alcohol Studies, Virginia Commonwealth University, Richmond, VA