Trait Impulsivity/Attention-Deficit/Hyperactivity Disorder A Genetic Liability for Criminality

Background: Cocaine-dependent individuals (CDI) display increased impulsivity. However, despite its multifactorial nature most studies in CDI have treated impulsivity monolithically. Moreover, the impact of attention-deficit/hyperactivity disorder (ADHD) has often not been taken into account. This study investigates whether CDI with ADHD (CDI+ADHD) differ from CDI without an ADHD diagnosis and healthy controls (HC) on several impulsivity measures. Methods: Thirty-four CDI, 25 CDI+ADHD and 28 HC participated in this study. Trait impulsivity was assessed with the motor, attentional and non-planning subscales of the Barratt Impulsiveness Scale (BIS-11). Neurocognitive dimensions of impulsivity were examined with the stop signal task (SST), delay discounting task (DDT) and information sampling task (IST). Results: Relative to HC, both CDI and CDI+ADHD scored higher on all BIS-11 subscales, required more time to inhibit their responses (SST) and sampled less information before making a decision (IST). Greater discounting of delayed rewards (DDT) was only found among CDI+ADHD. Compared to CDI without ADHD, CDI+ADHD scored higher on the BIS-11 non-planning and total scale and showed higher discounting rates. Conclusion: CDI score higher on several indices of impulsivity relative to HC, regardless of whether they have concomitant ADHD or not. CDI+ADHD are specifically characterized by a lack of future orientation compared to CDI without ADHD.

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Genetic effects on the variation and covariation of attention deficit-hyperactivity disorder (ADHD) and oppositional-defiant disorder/conduct disorder (ODD/CD) symptomatologies across informant and occasion of measurement

Psychological Medicine ◽

10.1017/s0033291701004792 ◽

2002 ◽

Vol 32 (1) ◽

pp. 39-53 ◽

Cited By ~ 110

Author(s):

T. S. NADDER ◽

M. RUTTER ◽

J. L. SILBERG ◽

H. H. MAES ◽

L. J. EAVES

Keyword(s):

Attention Deficit Hyperactivity Disorder ◽

Conduct Disorder ◽

Oppositional Defiant Disorder ◽

Attention Deficit ◽

Genetic Factors ◽

Multiple Informants ◽

Genetic Liability ◽

Hyperactivity Disorder ◽

Oppositional Defiant ◽

Co Morbidity

Background. Previous studies have shown that the presence of conduct disorder may contribute to the persistence of attention deficit-hyperactivity disorder (ADHD) symptomatology into adolescence; however, the aetiological relationship between the two phenotypes remains undetermined. Furthermore, studies utilizing multiple informants have indicated that teacher ratings of these phenotypes are more valid than maternal reports.Methods. The genetic structure underlying the persistence of ADHD and oppositional-defiant disorder/conduct disorder (ODD/CD) symptomatologies as rated by mothers and teachers at two occasions of measurement was investigated on a sample of 494 male and 603 female same sex adolescent twin pairs participating in the Virginia Twin Study of Adolescent Behavioral Development (VTSABD).Results. Using structural modelling techniques, one common genetic factor was shown to govern the covariation between the phenotypes across informants and occasion of measurement with additional genetic factors specific to ODD/CD symptomatology and persistence of symptomatology at reassessment. Genetic structures underlying the phenotypes were, to some extent, informant dependent.Conclusions. The findings indicate that it is unlikely that the co-morbidity between ADHD and ODD/CD is due to environmental influences that are independent of ADHD. Rather it is likely to be due to a shared genetic liability either operating directly, or indirectly through gene–environment correlations or interactions. The covariation between phenotypes across informants and time is governed by a common set of genes, but it seems that ODD/CD is also influenced by additional genetic factors. Developmentally, different forms of genetic liability control ADHD in males and inattention in females.

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