1. aker, L.A., Barton, M., & Raine, A. (2002). The Southern California Twin Register at USC. Twin Research, 5, pp 456-459.  PMID 12537876  Overview of the Southern California Twin Register, result of efforts to recruit twins of all ages in Los Angeles and surrounding areas. Register includes ethnically diverse sample of twin pairs (over 2600 at the time), drawn primarily from computerized records of enrollments in local public school districts. The register sample appears comparable in sex and ethnic distributions to general public school population of greater Los Angeles.
  2. Baker, L.A., Bezdjian, S., & Raine, A. (2006).  Behavioral Genetics:  The Science of Antisocial Behavior, Law and Contemporary Problems, 69(1-2): 7-46.  PMID: 18176636  Extensive literature review of genetic studies of ASB and the externalizing spectrum.
  3. Baker, L.A., Barton, M., Lozano, D.I., Raine, A., Fowler, J. H. (2006).  The Southern California Twin Register at the University of Southern California:  II.  Twin Research  Overview of the expanded USC Twin Register (over 5000 pairs), based on both school and voter record data. Also describes RFAB, based on 605 twin pairs who are participating in a longitudinal study of behavioral problems during childhood and adolescence. Baseline rates of conduct problems, depression and anxiety disorders, and attention-deficit/hyperactivity disorder diagnoses in RFAB are shown to be comparable to non-twins in this age range.
  4. Zumberge, A., Baker, L.A. & Manis, F.R. (2007). Focus on words: Genetic and environmental influences in reading and inattention. Beh Gen 37:284–293. PMID 17265136  Moderate and significant phenotypic correlations among reading, inattention and IQ, but not between impulsivity and the other variables. A and C largely account for variation in reading, inattention, and IQ and their covariation, whereas specific environmental influences contribut primarily to variation in impulsivity. Acting through a common factor, a portion of the genetic influences on reading ability appeared to be shared with influences affecting IQ as well as those affecting inattention. Contribution of phonological awareness to remaining unique genetic influences on reading was explored through additional analyses, which showed a.two-common-factor model, with a strongly genetic general cognitive ability factor affecting affecting reading, inattention, and IQ, and an equally strongly genetic second common factor, which captured variability in reading ability that was related specifically to phonological processing. The processes involved in reading, therefore, seem to involve genetic and environmental influences that are part of both a general cognitive system and a system more specific to reading and phonology.
  5. Baker, L.A., Jacobson, K.C., Raine, A., Lozano, D.I., & Bezdjian, S.  (2007). Genetic and environmental bases of antisocial behavior in children:  I. A multi-informant twin study.  Journal of Abnormal Psychology, 116 (2): 219-235.  PMID: 17516756  Multivariate genetic analysis of multi-rater (child, teacher, parent) measures of ASB—based on symptom counts for conduct disorder, ratings of aggression, delinquency, and psychopathic traits–revealed a highly heritable (96%) common ASB factor across informants. The best fitting multivariate model required informant-specific genetic, environmental, and rater effects for variation in observed ASB measures. The results suggest that parent, children, and teachers have only a partly “shared view” and that the additional factors that influence the “rater-specific” view of the child’s antisocial behavior vary for different informants. This is the first study to demonstrate strong heritable effects on ASB in ethnically and economically diverse samples, andhighlights the importance of a broad, general measure obtained from multiple sources as a plausible construct for future investigations of specific genetic mechanisms in ASB.
  6. Baker, L.A. (2007).  Biology of family relationships:  What behavior genetic studies tell us.  DePaul Law Review, 56(3): 857-866.
  7. Baker, L.A., Raine, A., Liu, J-H., & Jacobson, K.C. (2008) Differential genetic and environmental influences on reactive and proactive aggression in children.  Journal of Child Abnormal Psychology 36(8):1265–1278. PMID: 18615267  Demonstrated strong fit for phenotypic two-factor model of reactive and proactive aggression, which held across gender and three informant sources (child, caregiver, teacher). Genetic and shared environmental influences were evident for both forms of aggression (ACE fit best for both caregiver and teacher reports, with males=females), but genetic correlations between reactive and proactive aggression were less than unity, further suggesting at least partial etiological independence.  Gene-environment influences also varied across informant, with sex differences being significant in child self reports (AE in boys; CE in girls) for both Reactive and Proactive forms.  Males exhibit greater aggression than females in both forms for all raters; ethnic/race differences were also apparent for both reactive (Black>White>Asian) and proactive aggression (Black>White=Asian).
  8. Tuvblad, C., Zheng, M., Raine, A., & Baker, L.A.  (2009) A common genetic factor explains the covariation among ADHD ODD and CD symptoms in 9-10 year old boys and girls.  Journal of Child Abnormal Psychology, 37:153-167.  PMID: 19015975  A latent externalizing behavior factor can explain covariance among ADHD, ODD and CD symptoms. Genetic influences explained more than half of the variance in this externalizing factor in both boys and girls. There were also unique genetic and environmental influences in each set of symptoms, suggesting some etiological independence of the three disorders.
  9. Tuvblad, C., Raine, A., Zheng, M. & Baker, L.A. (2009). Genetic and environmental stability differs in reactive and proactive aggression. Agg Beh, 35(6): 437-452. PMID:  19688841 Genetic and environmental stability in reactive and proactive aggression (parent ratings) appear stable from 9–10 to 11–13 years old (r = .50-.54). Stability in reactive aggression appears due to genetic and non-shared environmental influences, whereas the continuity in proactive aggression is primarily genetically mediated. Sex diffs in means but not ACE. Results further support distinction between reactive and proactive forms of aggression.
  10. Isen, J. D., Baker, L.A. & Raine A., Bezdjian, S.  (2008).  Genetic and environmental influences on the Junior Temperament and Character Inventory in a preadolescent twin sample. Behavior Genetics, 39:36–47. PMID: 19043782 PMCID: PMC2609904. Shared environmental influences on Cooperativeness were substantial. Significant heritability estimates were obtained for Self-directedness and Harm Avoidance, but not Novelty Seeking, Reward Dependence or Persistence. With the exception of Harm Avoidance, each of the scales failed to show measurement invariance with respect to sex, suggesting these scales may differ in meaning for boys and girls at this age.
  11. Gao, Y., Baker, L. A., Raine, A., Wu, H., & Bezdjian, S. (2009). Brief report: Interaction between social class and risky decision-making in children with psychopathic tendencies. Journal of Adolescence, 32(2), 409-414. PMID: 18986696 doi:10.1016/j.adolescence.2008.09.001 Preadolescent community twins (N  = 298) were assessed on decision-making (Iowa Gambling) and behavior inhibition (Porteus Maze) tasks, while psychopathic tendencies and socioeconomic status were assessed by the child’s caregiver. A significant interaction was observed whereby risky decision-making was associated with psychopathic tendencies only in children from benign home environments. Findings support a biosocial interaction perspective on child psychopathy, suggesting that risky decision-making may particularly predispose to psychopathic traits in children from benign home backgrounds.
  12. Gao, Y., Tuvblad, C., Raine, A., Lozano, D.I., & Baker, L.A. (2009). Genetic and environmental influences on frontal EEG asymmetry and alpha power in 9-10 year old twins. Psychophysiology, 46(4): 787–796, PMID: 19386046 Resting frontal asymmetry and alpha power were examined in 951 9–10-year-old twins. Both males and females showed (1) modest but significant genetic variance in frontal asymmetry (11–28%) with additional non-shared environmental influences, and (2) high heritability of alpha power (71–85%). The genetic architecture of frontal asymmetry and alpha power in late childhood appears similar to that in adulthood. The high non-shared environmental influences on frontal asymmetry may reflect environmentally influenced individual differences in the maturation of frontal cortex as well as state-dependent influences on specific measurements.
  13. Bezdjian, S., Baker, L., Lozano, D.I. & Raine, A.  (2009).  Assessing inattention and impulsivity in children in the Go/NoGo task. British Journal of Developmental Psychology, 27: 365-383. PMID:  19812711 Behavioral performance in Go/NoGo was compared with caregiver and teacher reports of inattention and hyperactivity-impulsivity at age 9-10 years old.  NoGo errors correlated with hyperactivity-impulsivity, while Go errors correlated with inattention (both caregiver and teacher reports).  H-I and INATT were highly intercorrelated, however, for both teacher and caregiver reports, and there were significant cross correlations with Go and NoGo errors (which were virtually uncorrelated).  Highlights difficulty disentangling H-I and INATT in surveys, and suggests lab tasks such as NoGo may more clearly distinguish these constructs.
  14. Baker, L., Tuvblad, C., Reynolds, C., Zheng, M. & Raine, A.  (2009).  Resting heart rate and the development of antisocial behavior from age 9-14:  Genetic and environmental influences. Development and Psychopathology 21: 939–960. PMID: 19583891 A novel finding from this research involves a genetic analysis of the well-established negative association between low-resting heart rate and antisocial behavior. While replicating this inverse relationship in RFAB (low resting heart rate measured at ages 9–10 correlates negatively with ASB at both ages 9-10 and 11–13), genetic analyses revealed that this relationship is explained entirely explained by genetic covariation. Although the heritable component of heart rate explained only a small portion (1–4%) of the substantial genetic variance in ASB, children with low-resting heart rate appear genetically predisposed toward externalizing behavior problems as early as 9 years old.
  15. Tuvblad, C., Jacobson, K.C., Isen, J.., Lozano, D.I, Raine, A.,. Baker, L.A., (2010). Genetic and environmental etiology of sympathetic arousal and parasympathetic activation in children. Behavior Genetics:  40(4): 452-466.  PMID: 20162348 Nearly all of the genetic and environmental influences on respiratory sinus arrhythmia, heart rate, skin conductance level, and NS-SCRs. were accounted for by two latent factors, supporting the validity of separate sympathetic (A=.27, C=.28 in males; A=.231, C-.41 in females) and parasympathetic constructs (A=.27, C=.23 in males; A=.35, C=.18 in female). Some measure specific A in RSA and SCL, and measure specific C in SCL
  16. Isen, J., Raine, A., Baker, L.A., Dawson, M. Lozano, D.I. & Bezjian, S. (2010).  Sex-specific association between psychopathic traits and electrodermal reactivity in children. Journal of Abnormal Psychology, 119(1): 216-225.  PMID: 20141258 Reduced skin conductance response (SCR) magnitude (hyporeactivity) is characteristic of boys with higher psychopathic scores, suggesting that it is a biological marker of a manipulative and deceitful orientation in males. No association was found between SCRs and psychopathic personality in girls, suggesting sex-specific etiologies of these traits in childhood.
  17. Yeh, M., Jacobson, K., Baker, L.A. & Raine, A. (2011) Child psychopathic traits moderate relationships between parental affect and child aggression. Journal of the American Academy of Child and Adolescent Psychiatry, 50(10): 1054-1064. PMID: 21961779 Negative parenting has less impact on ASB among children who are high on psychopathic personality traits. Children low on psychopathy scores showed decreasing aggressive and conduct disorder symptoms as positive affect increased. Children high on psychopathy scores showed elevated aggressive and conduct disorder symptoms regardless of affect level. This interaction was not found for negative affect. Results imply that negative parenting detrimentally affects children’s problem behavior regardless of existing psychopathic traits, while children high on psychopathy scores may be less responsive to ineffective parenting.
  18. Ericson, M., Tuvblad, C., Raine, A., Young-Wolff, K., Baker, L.A.  (2011). The heritability and longitudinal stability of schizotypal traits during adolescence. Behavior Genetics, 41 (4): 499-511. PMID: 21369821; PMCID: PMC3123391 The 22-item Schizotypal Personality Questionnaire-Child version (SPQ-C) was found to be factorially similar to the adult version of this instrument, with three underlying factors (Cognitive-Perceptual, Interpersonal-Affective, and Disorganization). Each factor was heritable at age 11–13 years (h2  = 42–53%) and 14–16 years old (h2  = 38–57%). Additive genetic and unique environmental influences acted through a single common latent factor, with additional genetic effects specific to both Interpersonal-Affective and Disorganization subscales at each occasion. The longitudinal correlation between the latent schizotypy factor was r  = 0.58, and genetic influences explained most of the stability in this latent factor over time (81%). These longitudinal data demonstrate significant genetic variance in schizotypal traits, with moderate stability between early to middle adolescence. In addition to common influences between the two assessments, there were new genetic and non-shared environmental effects that played a role at the later assessment, indicating significant change in schizotypal traits and their etiologies throughout adolescence.
  19. Bezdjian, S., Raine, A., Baker, L.A.  & Lynam, D.  (2011) Psychopathic personality in children: Genetic and environmental influences. Psychological Medicine, 41 (3): 589-600. PMID: 20482945; PMCID:  PMC3113684 Confirmatory factor analyses of CPS subscales revealed an optimal two-factor solution (callous/disinhibited and manipulative/deceitful). Bivariate genetic modeling of the two computed factor scores revealed significant genetic as well as unique environmental influences on psychopathic personality traits in both boys and girls, with heritability estimates of 0.64 and 0.46, respectively, in boys and 0.49 and 0.58, respectively, in girls. No shared environmental influences on psychopathic personality traits were found. The relationship between the two CPS factors appears mediated by both genetic and unique environmental factors common to both traits.
  20. Bezdjian, S., Tuvblad, C., Raine, A., & Baker, L.A. (2011). The genetic and environmental covariation among psychopathic personality traits, reactive and proactive aggression in childhood.  Child Development, 82(4): 1267–1281. PMID: 21557742 Significant common genetic influences are shared by psychopathic personality traits and aggressive behaviors using both caregiver (mainly mother) and child self-reports. Significant genetic and non-shared environmental influences specific to psychopathic personality traits and reactive and proactive aggression were also found, suggesting etiological independence among these phenotypes. Additionally, the genetic relation between psychopathic personality traits and aggression was significantly stronger for proactive than reactive aggression when using child self-reports.
  21. Bezdjian, S., Baker, L.A., & Tuvblad, C. (2011).  Genetic and environmental influences on impulsivity:  A meta-analysis of twin, family and adoption studies. Clinical Psychology Review, 31: 1209-1223.  PMID: 21889436 Meta-analysis of twin, family and adoption studies estimated magnitude of gene and environmental influences on impulsivity. Best fitting model for 41 key studies (58 independent samples from 14 month old infants to adults; N=27,147) included equal proportions of variance due to G (0.50) and E (0.50) influences, with genetic effects being both A (0.38) and D (0.12) and no effect of C. Age, sex, and study design (twin vs. adoption) were all significant moderators of gene-environmental effects. Relative contribution of genes (broad heritability) and unique environmental effects were important from childhood to adulthood, with total genetic effects being stronger in children and stronger in males than in females.
  22. Yang, Y-L., Joshi, A.A., Joshi, S.H., Baker, L.A., Narr, K.L., Raine, A., Thompson, P.M., & Damasio, H.  (2012). Genetic and environmental influences on cortical thickness among 14 year old twins.  Neuroreport, 22;23(12):702-6. PMID: 22713927 Analyzed structural MRI data from a subset of W3 participants: 108 14-year-old healthy twins (54 females/54 males) to determine relative contributions of genes and environment toward regional variations in gray matter thickness across the cortex. ACE models fit to cortical thickness values obtained at a high spatial resolution showed considerable regional variability in A on cortical thickness after controlling for sex. Regions with A> 80% in prefrontal cortex, predominantly bilateral dorsolateral and mesial superior frontal regions. No region showed prominent C effects, but E effects over 80% were found in parietal association regions.
  23. Wang, P., Baker, L.A., Gao, Y., Raine, A., Lozano, D.I. (2012). Psychopathic traits and physiological responses to aversive stimuli in children aged 9-11 years.  Journal of Abnormal Child Psychology, 40(5):759-69; PMID: 22228313 Autonomic response anomalies (larger HR acceleration and fewer NS (non-specifi)c SCRs) were associated with psychopathic traits (age 9-10) during anticipation of signaled white-noise bursts N=843 at Wave 1. Atypical electrodermal and cardiovascular response patterns in psychopathic individuals may be biological indicators of fearless and disinhibition. However, two divergent patterns appeared for HR and SCR: (1) larger HR acceleration was specific to callousness-disinhibition factor of psychopathic traits while reduced NS-SCR was only associated with manipulative-deceitfulness factor; 2) negative association between manipulative/deceitfulness factor and NS-SCR was only found in boys but not in girls. These findings replicated what has been found in psychopathic adults, suggesting that autonomic deficits present in children at risk may predispose them to later psychopathy. The divergent findings across psychopathic facets and sexes raised the possibility of different etiologies underlying psychopathy, which may in turn suggest multiple treatment strategies for boys and girls.
  24. Tuvblad, C., Gao, Y., Isen, J., Botwick, T., Raine, A., Baker, L.A. (2012). The heritability of the skin conductance orienting response: A longitudinal twin study.  Biological Psychology, 89 (1) 47-53.  PMID: 21945549 Examined gene-environmental etiology of skin conductance orienting response (SCOR) at ages 9–10, 11–13, and 14–16 years. The SCOR is an autonomic response to novel stimuli and indirectly reflects how much a person attends to and processes novel stimuli in the environment. SCOR deficits have been linked to a variety of externalizing problems, including psychopathy, ASB, and ADHD. Genetic influences explained 55%, 82%, and 48% of the total variance in SCOR at Waves 1, 2, and 3, respectively, with the remaining variance explained by non-shared environment. SCOR was moderately stable phenotypically across ages (r = .38 to .51). Genetic influences contributed between 7% and 30% to the stability of SCOR. The genetic correlations among the three waves were high, ranging between 0.53 and 0.90, indicating substantial continuity in genetic influences from ages 9 to 16.
  25. Niv, S., Tuvblad, C., Raine, A., Baker, L. A. (2012) Heritability and longitudinal stability of impulsivity in adolescence. Behavior Genetics, 42: 378–392. PMID: 22089391Genetic and environmental stability of impulsivity was investigated using data from the Barratt Impulsiveness Scale (BIS) in Waves 2 and 3. Univariate genetic analyses for the three sub-scales (inattention, motor, and non-planning impulsivities) yielded moderate heritability estimates of 38–55% at ages 11–13, and 31–37% at ages 14–15. Multivariate genetic analyses at each wave suggest a latent common impulsivity factor, with 72% of the stability between these two latent impulsivity factors accounted for by genetic effects.
  26. Wang, P., Niv, S., Tuvblad, C., Raine, A & Baker, L.A. (2013). The genetic and environmental overlap between aggressive and non-aggressive antisocial behavior using the Self-report Delinquency Interview for Children and Adolescents. Journal of Criminal Justice 41(5):277-284. PMID: 24465061Psychometric and genetic analysis (cross-sectional) of SR-DI from Waves 1, 2, and 4. Sex differences in mean levels of ASB. Diverse change patterns of genetic and environmental emerged, as a function of sex and form of ASB, during the development from childhood to adolescence. Although there was some overlap in etiologies of aggressive and non-aggressive ASB, predominantly in C, their genetic overlap was moderate and the overlap in E was low. Results reinforced importance of sex differences and differentiating forms of ASB. AGG & Non-Agg correlate .5-.6 within each wave, and show moderate stability across waves.
  27. Tuvblad, C., Gao, Y., Wang, P., Botwick, T., Raine, A., & Baker, L.A.  (2013)  Heritability of the Iowa Gambling Task, A longitudinal twin study on decision making. Journal of Adolescence, 36(2):245-55. PMID: 23261073 Gene-environment etiology of decision-making in Iowa Gambling Task at waves 2-4 (ages 11-18). Variance across five 20-trial blocks could be explained by a latent decision-making factor within each wave, with genes explaining 35%, 20% and 46% of the variance in W2, W3 W4, respectively.. Block-specific non-shared environmental influences were also observed. The stability of decision-making was modest across development (r=.2 to .3), and genetic correlations between waves was low—rE explained more of stability. Youth showed a trend to choose less risky decks at later ages, suggesting some improvement in task performance across development. Similar to results on impulsivity, results highlight importance of unique experiences on individual differences.
  28. Tuvblad, C., Bezdjian, S., Raine, A., Baker, L.A. (2013). Psychopathic personality and negative parent-to-child affect: A longitudinal cross-lag twin study. Journal of Criminal Justice, 41(5): 331-341. Examined the direction and the genetic and environmental etiology of the association between negative parent-to-child affect and psychopathic personality from ages 9–10 to 14–16 years. Negative parent-to-child affect at ages 9–10 years influenced psychopathic personality at ages 14–16 years (both caregiver and youth reports). Both genetically and environmentally mediated parent-driven effects were important in development of psychopathic personality. Psychopathic personality at ages 9–10 years influenced negative parent-to-child affect at ages 14–16 years (caregiver reports only). Thus, children’s genetically influenced psychopathic personality seemed to evoke parental negativity at ages 14–16 years, These results illustrate the importance of investigating bi-directional relationships between parenting and the development of psychopathic personality.
  29. Niv, S., Tuvblad, C., Raine, A., & Baker, L.A. (2013). Aggression and rule-breaking: Heritability and stability of antisocial behavior problems in childhood and adolescence. Journal of Criminal Justice 41(5): 285-291. Examined the structure of gene-environmental influences on aggression and rule-breaking and their stability from childhood to mid-adolescence (Waves 1 and 3). Aggression and rule-breaking were influenced by a latent common factor of antisocial behavior (ASB) within each wave. During childhood, the common ASB factor was influenced by 41% A, 40% C and 19% E. In adolescence, 41% of variance in the common factor was novel (i.e., independent of childhood) and entirely genetic, while the remainder of variance was stable across time. Both aggression and rule-breaking within each wave had unique influences which were not common across subscales or waves, highlighting specificity of genetic and environmental effects on different problem behaviors at both ages .Future research into interventions for antisocial behavior problems in youth could focus on adolescence-specific environmental influences.
  30. Liu, J., Tuvblad, C., Li, L., Raine, A., Baker, L.A. (2013) Medical Record validation of Maternal Recall of Pregnancy and Birth Events from a Twin Cohort, Twin Research and Human Genetics: 16(4):845-60. PMID: 23725849 Assesses validity of maternal recall for perinatal variables 8–10 years after pregnancy in RFAB twins. Retrospective information collected 8–10 years after the delivery event in mothers (N = 611) and compared with medical records. Recall of most variables showed substantial to perfect agreement (r = 0.60–1.00), except for specific medical problems during pregnancy (r ≤ 0.40) and substance use when mothers provided continuous data (e.g., number of cigarettes per day; r ≤ 0.24). With exception of delivery method, neonatal intensive care unit admission, birth weight, neonatal information, and post-delivery complications were also recalled with low accuracy. For mothers of twins, maternal recall is generally a valid measure for perinatal variables 10 years after pregnancy. However, caution advised regarding variables such as SU, medical problems, birth length, and post-delivery complications.
  31. Liu, J., Tuvblad, C., Raine, A., and Baker, L. A. (2013).  Genetic and environmental influences on nutrient intake. Genes and Nutrition, 8(2):241-52. PMID 23055091. Structural equation modeling of Wave 2 (age 11-13) 3-day food diaries for N=358 twins revealed genetic influences accounted for a significant portion of the total variance in total energy (48 %), macronutrients (35–45 %), minerals (45 %), and vitamins (21 %). Consistent with previous studies, the shared environment appeared to contribute little to nutritional intake.
  32. Baker, L.A., Tuvblad, C., Wang, P., Gomez, K., Bezdjian, S., Niv, S.,  & Raine, A. (2013) The Southern California Twin Register at the University of Southern California: III. Twin Research. 16(1):336-43PMID 23394193 Provides an overview of USC RFAB sample and study design for Waves 1-5 (N=780 families; 1569 twins/triplets). Summarizes key findings to date, regarding (a) relationships of ASB with biological risk factors, especially autonomic deficits including low resting heart-rate, reduced skin conductance responses; (b) relationships of ASB with social risk factors, including reduced positive affect in parents; (d) longitudinal stability of ASB and its various social and biological risk factors; (e) genetic effects on externalizing behavior problems and their relationships to biological and social risk factors.
  33. Tuvblad, C., Bezdjian, S., Schug, R., Ericson, M., Raine, A., Baker, L.A. (2014). The heritability of psychopathic personality in 14 to 15 year old twins: A multi-rater, multi-measure approach, Psychological Assessment (3):705-716. PMID: 4155407 Multivarate genetic analysis of three psychopathy measures at Wave 3: The Child Psychopathy Scale (CPS) and the Antisocial Process Screening Device (APSD) (youth and caregiver report) and Psychopathy Checklist: Youth Version (PCL:YV) scored by trained testers. A one-factor common pathway model fit best. Genes explained 69% of the variance in the latent psychopathic personality factor, while non-shared environmental influences explained 31%. Measurement-specific genetic effects accounted for between 9% and 35% of the total variance in each of the measures, except for PCL:YV where all genetic influences were in common with the other measures. Measure-specific non-shared environmental influences were found for all measures, explaining between 17% and 56% of the variance. These findings provide further evidence of the heritability in psychopathic personality among adolescents, although these effects vary across the way in which these traits are measured, in terms of both informant and instrument used.
  34. Bezdjian, S., Wang, P., Tuvblad, C., Raine, A., Baker, L.A. (2014). Motor impulsivity during childhood and adolescence: A longitudinal biometric analysis of the Go/NoGo task in 9-18 year old twins. Developmental Psychology, 50 (11), 2549-57. doi/10.1037/a0038037  PMID: 25347305 Examined stability and heritability of one component of the multifaceted impulsivity construct, namely, motor impulsivity, based on errors of commission from the visual Go/NoGo task in Waves 1-4 (age 9-18). Phenotypically, average performance improved across age (i.e., fewer no-go errors during later assessments). Results provide evidence that common genetic effects influence motor impulsivity in childhood, and these effects remain important throughout adolescence (heritability ranges from 22-41% across waves). Additionally, nonshared environmental effects were also greatly important across development and contributed both to common factors as well as to unique specific factors. This may be attributable to the accumulation of unique experiences across childhood and adolescence, highlighting the importance of learning and individual environmental factors in the development of impulse control across development.
  35. Gao, Y., Tuvblad, C., Schell, A., Raine, A., & Baker, LA. (2015).  Skin conductance fear conditioning impairments and aggression: A longitudinal study.  Psychophysiology 52: 288-295; published online Sept 1 2014. PMID: 25174802. Investigates association between fear conditioning (Wave 4) and reactive and proactive aggression in males and females when aged 10, 12, 15, and 18 years old (Waves 1-4). Individuals persistently high on proactive aggression measures had significantly poorer conditioned responses at 18 years old when compared to others. This association was not found for reactive aggression. Consistent with prior literature, findings suggest that persistent antisocial individuals have unique neurobiological characteristics and that poor autonomic fear conditioning is associated with the presence of increased instrumental aggressive behavior.
  36. Wang, P., Gao, Y., Tuvblad, C., Raine, A., Baker, L.A. (2015). Genetic Covariance between Psychopathic Traits and Anticipatory Skin Conductance Responses to Threat: Evidence for a Potential Endophenotype.  Development and Psychopathology, Published online: 09 January 2015 DOI: http://dx.doi.org/10.1017/S0954579414001424. Investigated heritability of two SCR measures (anticipatory SCRs to impending aversive stimuli and unconditioned SCRs to the aversive stimuli themselves) in Wave 1 countdown (752 twins). Also investigated the genetic and environmental sources of the covariance between these SCR measures and two psychopathic personality traits: impulsive/disinhibited (reflecting impulsive–antisocial tendencies) and manipulative/deceitful (reflecting the affective–interpersonal features). For anticipatory SCRs, 27%, 14%, and 59% of the variation was due to A, C and E, respectively, while percentages for unconditioned SCRs were 44%, 2%, and 54%. The manipulative/deceitful (not impulsive/disinhibited) traits were negatively associated with both anticipatory SCRs (r . –.14, p , .05) and unconditioned SCRs (r . –.17,p , .05) in males only, with the former association significantly accounted for by genetic influences (rg . –.72). Reduced anticipatory SCRs represent a candidate endophenotype for the affective–interpersonal facets of psychopathic traits in males. NOTE the change in how we refer to the CPS factors in this paper, as per Chris Patrick recommendations in reviews.
  37. Niv, S. Ashrafulla, S., Tuvblad, C., Jackson, N., Raine, A., Baker, L.A. (2015). Childhood EEG frontal alpha power as a predictor of adolescent antisocial behavior: A twin heritability study, Journal of Biological Psychology, 105C, 72-76.  PMID: 25456277 High EEG frontal alpha power (FAP) is thought to represent a state of low arousal in the brain, which has been related in past research to antisocial behavior (ASB). We investigated a longitudinal sample of 900 twins in two assessments in late childhood (W1) and mid-adolescence (W3) to verify whether relationships exist between FAP and both aggressive and nonaggressive ASB as measured by the CBCL. FAP was calculated using connectivity analysis methods that used principal components analysis to derive power of the most dominant frontal activation. Significant positive predictive relationships emerged in males between childhood FAP and adolescent aggressive ASB using multilevel mixed modeling, although no concurrent relationships were found. Using bivariate biometric twin modeling analysis, the relationship between childhood FAP and adolescent aggressive ASB in males was found to be entirely due to genetic factors, which were correlated r = 0.22.
  38. Tuvblad, C., Wang, P., Bezdjian, S., Raine, A., & Baker, L. A. (2015). Psychopathic personality development from ages 9 to 18: Genes and environment. Development and Psychopathology. May 5:1-18 (Epub ahead of print) PMID: 25990131 doi:10.1017/S0954579415000267 Biometric latent growth model for CPS Waves 1-4, using piecewise model for G1 (all four waves) and G2 (waves 3-4 to account for a turning point from childhood to adolescence. Variations in levels and both change scores were mainly due to genetic (A) and nonshared environmental (E) influences (i.e., AE structure for G0, G1, and G2). No sex differences were found except on the mean values of level and change scores. Based on caregiver ratings, about 81% of variance in G0, 89% of variance in G1, and 94% of variance in G2 were explained by genetic factors, whereas for youth self-reports, these three proportions were 94%, 71%, and 66%, respectively. The larger contribution of genetic variance and covariance in caregiver ratings than in youth self-reports may suggest that caregivers considered the changes in their children to be more similar as compared to how the children viewed themselves.
  39. Young-Wolff, K., Wang, P., Tuvblad, C., Baker, L.A., Raine, A., & Prescott, C.A. (2015). Drinking experience uncovers genetic influences on alcohol expectancies across adolescence.  Addiction 110(4): 610-8. PMID: 25586461.Investigates whether drinking onset moderates gene-environment contributions to alcohol expectancies across adolescence. Longitudinal genetic analysis of Waves 1, 2, 3 (1292 male and female twins) of social behavioral (SB) subscale from the Alcohol Expectancy Questionnaire for adolescents (AEQ-A). Drinking onset defined as >1 full drink of alcohol. Alcohol expectancies increased over age, more rapidly increasing following onset of drinking. The importance of gene- environmental influences on SB scores varied with age and drinking status: variation prior to drinking onset was attributed solely to environmental influences, whereas all post-onset variation was attributed to genetic influences. (no sex differences)Only environmental factors explain beliefs about the social and behavioral consequences of alcohol use prior to drinking onset, whereas genetic factors explain an increasing proportion of the variance in these beliefs after drinking onset.
  40. Park, A.E., Huynh, P., Schell, A.M. & Baker, L.A. (2015). Relationship between obesity, negative affect, and basal heart rate in predicting heart rate reactivity to psychological stress among adolescents.  Int. J. Psychophysiol., Aug: 97(2):139-44. PMID: 26049136. Examined the separate effects of obesity and negative affect on both cardiovascular and skin conductance responses to stress (e.g., during a serial subtraction math task) in adolescents, while controlling for baseline levels of autonomic activity during rest. Both obesity and negative affect had independent and negative associations with cardiovascular reactivity, such that reduced stress responses were apparent for obese adolescents and those with high levels of negative affect. In contrast, neither obesity nor negative affect was related to skin conductance responses to stress, implicating specifically noradrenergic mechanisms rather than sympathetic mechanisms generally as being deficient. Moreover, baseline heart rate was unrelated to obesity in this sample, which suggests that heightened baseline of sympathetic activity is not necessary for the reduced cardiovascular reactivity to stress.
  41. Jelenkovic, A., Yokoyama, Y., et al. (2015) Zygosity differences in height and body mass index of twins from infancy to old age: A study of the CODATwins Project.  Twin Res. Human. Genet., Oct; 18(5):557-570.  doi: 10.1017/thg.2015.57. Epub 2015 Sep 4. PMID: 26337138 Analyzed zygosity differences in mean values and variances of height and body mass index (BMI) among male and female twins from infancy to old age. Based on an international database of 54 twin cohorts participating in the COllaborative project of Development of Anthropometrical measures in Twins (CODATwins), and included 842,951 height and BMI measurements from twins aged 1 to 102 years. DZ twins were consistently taller than MZ twins (2.0 cm in childhood and adolescence; 0.9 cm in adulthood), had 1.7% greater height and 1.9% greater BMI than MZ twins; these percentage differences were largest in middle and late childhood and decreased with age in both sexes. The variance of height was similar in MZ and DZ twins at most ages. In contrast, the variance of BMI was significantly higher in DZ than in MZ twins, particularly in childhood. In conclusion, DZ twins were generally taller and had greater BMI than MZ twins, but the differences decreased with age in both sexes.
  42. Silventoinen, K., Jelenkovic, A., et al. (2015).  The CODATwins Project: The cohort description of collaborative project of development of anthropometrical measures in twins to study macro-environmental variation in genetic and environmental effects on anthropometric traits.  Twin Res. Hum. Genet., Aug; 18(4):348-60.  doi: 10.1017/thg.2015.29.  PMID 26014041Introduces the CODATwins Project, which includes 67 twin studies, including both monozygotic (MZ) and dizygotic (DZ) twins. Involves individual level data on height and weight including repeated measurements, birth related traits, background variables, education and smoking. By the end of 2014, 48 projects participated. Together, we have 893,458 height and weight measures (52% females) from 434,723 twin individuals, including 201,192 complete twin pairs (40% monozygotic, 40% same-sex dizygotic and 20% opposite-sex dizygotic) representing 22 countries.
  43. Sobhani, M., Baker, L.A., Martins, B., Tuvblad, C., Aziz-Zadeh, L. (2015).  Psychopathic traits modulate microstructural integrity of right uncinated fasciculus in a community population.  NeuroImage: Clinical.  8:32-38. doi: 10.1016/j.nicl.2015.03.012. PMID: 26106525 Young-adult follow-up MRI study of a subset of RFAB twins identified as having high and low levels of psychopathy, to investigate whether psychopathic traits modulate microstructural integrity of uncinate fasciculus (UF), and whether this relationship is dependent upon levels of trait anxiety, which is sometimes used to distinguish subtypes of psychopathy. Reveaedl a negative association between psychopathic traits and microstructural integrity of UF, supporting previous findings that individuals with psychopathy possess emotional and behavioral abnormalities. However, no moderation of the relationship by trait anxiety was discovered. Findings provide further support for the notion of altered amygdala–VMPFC connectivity in association with higher psychopathic traits.
  44. Jackson, N., Isen, J., Khoddam, R., Irons, D., Tuvblad, C., Iacono, W., McGue, M., Raine, A., & Baker, L.A. (2016) The impact of adolescent marijuana use on intelligence: Results from two longitudinal twin studies.  Proceedings of the National Academy of Sciences, 13(5): E500-508. PMID: 26787678  Examined associations of marijuana use with changes in intellectual performance in two longitudinal studies of adolescent twins (n = 789 and n = 2,277). Used a quasiexperimental approach to adjust for participants’ family background characteristics and genetic propensities, helping us to assess the causal nature of any potential associations. Standardized measures of intelligence were administered at ages 9-12 y, before marijuana involvement, and again at ages 17-20 y. Marijuana use was self-reported at the time of each cognitive assessment as well as during the intervening period. Marijuana users had lower test scores relative to nonusers and showed a significant decline in crystallized intelligence between preadolescence and late adolescence. However, there was no evidence of a dose-response relationship between frequency of use and intelligence quotient (IQ) change. Furthermore, marijuana-using twins failed to show significantly greater IQ decline relative to their abstinent siblings. Evidence from these two samples suggests that observed declines in measured IQ may not be a direct result of marijuana exposure but rather attributable to familial factors that underlie both marijuana initiation and low intellectual attainment.
  45. Isen, J., Baker, L.A., Kern, M., Raine, A., and Bezdjian, S. (2018). Unmasking the association between psychopathic traits and adaptive functioning in children.  Pers. Individ. Dif. 124, April, pp 57-65.  doi:10.1016/j.paid.2017.11.043
  46. Fullerton, A.F., Jackson, N., Tuvblad, C., Raine, A., Baker, L.A. (2019). Early childhood head injury attenuates declines in impulsivity and aggression across adolescent development in twins.  Neuropsychology, https://psycnet.apa.org/doi/10.1037/neu0000570 .
  47. Tuvblad, C., Wang, P., Patrick, C.J., Berntsen, L., Raine, A., Baker, L.A. (2019). Genetic and environmental influences on disinhibition, boldness, and meanness as assessed by the triarchic psychopathy measure in 19-20 year old twins.  Psychological Medicine, 49(9): 1500-1509. DOI:10.1017/S0033291718002052
  48. Silventoinen, K., Jelenkovic, A., et al. (2019).  Parental education and genetics of BMI from infancy to old age: A pooled analysis of 29 twin cohorts. Obesity 27(5): 855-686. https://doi-org.libproxy2.usc.edu/10.1002/oby.2245
  49. Silventoinen, K., Jelenkovic, A., et al. (2019). The CODATwins Project:  Current status and recent finding from the Collaborative project of Development of Anthropometrical measures in Twins.  Twin Res. Hum. Genetics, 1-9. doi:10.1017/thg.2019.35
  50. Bertoldi, B., Perkins, E., Tuvblad, C., Oskarsson, S., Kramer, M., Latzman, R., Baker, L.A., Raine, A., Patrick, C. (2021). Pursuing the developmental aims of the triarchic model of psychopathy: Creation and validation of triarchic scales for use in the USC: RFAB https://doi.org/10.1017/s0954579420002060J
  51. elenkovic, A., Sund, R., Yokoyama, Y., Latvala, A., Sugawara, M., Tanaka, M., …Baker, L.A., …Sientoinen, K. (2020). Genetic and environmental influences on human height from infancy through adulthood at different levels of parental education. Scientific Reports, 10(1), 7974. https://doi.org/10.1038/s41598-020-64883-8
  52. Isen, J., Tuvblad, C., Younan, D., Ericson, M., Raine, A., Baker, L.A. (2021).  Developmental Trajectories of Delinquent and Aggressive Behavior: Evidence for Differential Heritability. Child Psychiatry Hum Dev  https://doi.org/10.1007/s10578-020-01119-w