The relationship between personality throughout adolescence and social anxiety disorder in young adulthood. A longitudinal twin study.

This study examined the longitudinal relationship between a range of personality related variables measured throughout adolescence, and social anxiety disorder (SAD) in young adulthood. In addition, we examined to what degree the phenotypic associations between personality and SAD could be attributed to shared genetic and environmental factors, respectively. A total of 3394 twins (56% females), consisting of seven national birth cohorts from Norway, participated in the study. Personality was measured with self-report questionnaires at three times throughout adolescence, and SAD was measured with a diagnostic interview in early adulthood (M = 19.1 years, SD = 1.2). Correlation and regression analyses were performed to examine phenotypic associations between personality and SAD. We then created four composite scores of personality, in which the personality variables from four different ages throughout adolescence were weighted relative to their importance for SAD. Finally, a series of Cholesky decomposition models were used to examine the underlying genetic and environmental influences on the phenotypic associations between composite scores of personality and SAD. The results showed that especially higher neuroticism, lower extraversion, higher levels of loneliness, and lower levels of resilience, self-efficacy and sense of coherence, were associated with SAD. The phenotypic correlations between composite scores of personality and SAD increased from 0.42 when personality was measured 6-7 years prior to the assessment of SAD, to 0.52 when personality was measured shortly before the assessment of SAD. These phenotypic associations were mainly due to genetic influences, indicating that personality in adolescence predicts SAD in early adulthood due to shared genetic influences rather than having direct 'causal' effects on SAD.

The longitudinal relationship between life events and loneliness in adolescence: A twin study.

The aim of the study was to examine associations between life events and self-assessed loneliness in adolescence. We used data from a Norwegian population-based twin sample including seven birth cohorts (N = 2,879, 56% females). The participants completed self-report questionnaires three times throughout adolescence, with 2 years in between (i.e., 12-18 years old at Wave 1). By using a random intercept cross-lagged panel model (RI-CLPM), we were able to separate stable influences in the measured constructs from the within-person changes at each measurement occasion. In addition, using data from twins allowed us to examine to what degree the associations between life events and loneliness were genetic and/or environmental in nature. The results showed moderate stability of both loneliness and aggregation scores of life events throughout adolescence. The life events were assigned to clusters based on their independence (i.e., events considered dependent or independent on a person's behavior) and desirability (i.e., positive or negative). The time-stable between-person variance in all three measures, loneliness and person-dependent positive and negative life events, could almost exclusively be accounted for by genetic factors. However, as expected, also shared environmental factors influenced person-independent life events. The associations between time-stable between-person variance in loneliness and life events were small, and nearly exclusively due to shared genetic influences. Furthermore, life events do not seem to predict changes in loneliness or vice versa. In conclusion, the self-reported levels of loneliness throughout adolescence seems to be independent of life events. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Clustering psychopathology in male anabolic-androgenic steroid users and nonusing weightlifters.

INTRODUCTION: Prior research has demonstrated that personality disorders and clinical psychiatric syndromes are common among users of anabolic-androgenic steroids (AAS). However, the prevalence, expression, and severity of psychopathology differ among AAS users and remain poorly understood. In this study, we examine the existence of potential clinically coherent psychopathology subgroups, using cluster procedures. METHODS: A sample of 118 male AAS users and 97 weightlifting nonusers was assessed using the Millon Clinical Multiaxial Inventory-III (MCMI-III), measuring personality disorders and clinical syndromes. Group differences in MCMI-III scales were assessed using Wilcoxon-Mann-Whitney tests and Fisher's exact test. Agglomerative hierarchical clustering was used to identify clusters based on MCMI-III scale scores from the whole sample. RESULTS: AAS users displayed significantly higher scores on all personality disorder (except narcissistic) and clinical syndrome scales compared to nonusing weightlifters. The clustering analysis found four separate clusters with different levels and patterns of psychopathology. The "no psychopathology" cluster was most common among nonusing weightlifters, while the three other clusters were more common among AAS users: "severe multipathology," "low multipathology," and "mild externalizing." The "severe multipathology" cluster was found almost exclusively among AAS users. AAS users also displayed the highest scores on drug and alcohol dependence syndromes. CONCLUSIONS: AAS users in our sample demonstrated greater psychopathology than the nonusing weightlifters, with many exhibiting multipathology. This may pose a significant challenge to clinical care for AAS users, particularly as there appears to be significant variation in psychopathology in this population. Individual psychiatric profiles should be taken into consideration when providing treatment to this group. SIGNIFICANT OUTCOMES: As a group, AAS users displayed markedly greater psychopathology than nonusing weightlifters. Multipathology was common among AAS users. Four different subgroups of personality profiles were identified with distinct patterns of pathology and severity. LIMITATIONS: The cross-sectional nature of the study precludes inferences about causality. The study is limited by possible selection bias, as participants choosing to be involved in research may not be entirely representative for the group as a whole. The study is vulnerable to information bias, as the results are based on self-report measures and interviews.

Psychopathology among anabolic-androgenic steroid using and non-using female athletes in Norway.

Anabolic-androgenic steroids (AAS) are primarily used to improve physical appearance and increase lean muscle mass. Due to their masculinizing properties, the majority of people using AAS are men; however, AAS use among females may increase with changing body ideals trending towards a more muscular appearance. AAS use among males have been associated with risk-taking behavior, and increased prevalence of personality disorders and psychopathology. As a result of low perceived prevalence and stigma among females who use AAS, the relationship between AAS use and psychopathology in this population is not well-known. AAS using women (n = 16) and weight-lifting controls (WLC) (n = 16) completed questionnaires regarding AAS use, health and training information. Psychopathology was evaluated using the Millon Clinical Multiaxial Inventory-III (MCMI-III). Group differences on demographic variables and scores on MCMI-III scales were evaluated with Mann-Whitney U tests. The clinical cut-off was then applied to all MCMI-III scales and groups were compared using Fisher's exact test. AAS consumers demonstrated significantly greater psychopathology than WLC on several scales. Externalizing personality disorder scales were elevated among those who use AAS relative to controls, such as borderline (p < 0.001), antisocial (p = 0.007) and sadistic (p = 0.002), and in addition depressive (p = 0.012), negativistic (p = 0.001) and masochistic (p = 0.029) personality disorders scales. Furthermore, all clinical syndromes were elevated among AAS consumers. AAS consumers thus demonstrated multi-pathology, and 56% (n = 9) of the group met the clinical criteria for six or more disorders. Females who use AAS experience in general increased levels of psychopathology compared to WLC. Clinicians should be aware of these traits and the challenges they present in providing care to this population.

The role of sense of coherence and loneliness in borderline personality disorder traits: a longitudinal twin study.

BACKGROUND: Borderline personality disorder (BPD) implies having problems with identity and relations with other people. However, not much is known about whether these indications of BPD are present in adolescence, i.e., before personality disorders usually are diagnosed. In this study, we examined the prediction of an aspect of identity (i.e., sense of coherence [SOC]) and social relations (i.e., perceived loneliness) throughout adolescence on BPD traits in young adulthood. In addition, we examined to what degree the predictive ability could be attributed to genetic and environmental factors. We also examined whether life events in adolescence were related to BPD traits. METHODS: Three thousand three hundred ninety-one twins, consisting of seven national birth cohorts from Norway, participated in the study. SOC, loneliness and life events were measured three times throughout adolescence with self-report questionnaires, with 2 years in between measurements. BPD traits were measured at the end of adolescence around the age of 19 with a structured interview. Regression analyses were performed to examine the prediction of SOC, loneliness and life events on BPD traits. Cholesky decomposition models were then used to determine to what degree the associations were due to genetic and environmental influences. RESULTS: The prediction of SOC and loneliness on BPD traits increased from R = .25 (when measured 6 years prior to the assessment of BPD traits) to R = .45 (when measured shortly before the assessment of BPD traits). In addition, negative life events considered dependent on a person's behavior were related to BPD traits. Negative independent and positive dependent life events did not contribute to the prediction of BPD traits. Cholesky decomposition models showed that SOC and loneliness were associated with BPD traits mainly due to shared genetic influences (i.e., the proportion due to genetic influences ranged from 71 to 86%). Adding negative dependent life events to the prediction of BPD traits did not change these percentages. CONCLUSIONS: These findings indicate that the weaker SOC, the stronger feelings of loneliness, and the negative life events associated with BPD traits are mainly consequences of the genetic aspects of BPD traits, rather than having direct effects on levels of BPD symptoms.

Childhood trauma and borderline personality disorder traits: A discordant twin study.

A discordant twin design was utilized to examine the potentially causal effects of childhood trauma (CT; i.e., emotional abuse, physical abuse, sexual abuse, and witnessing violence) on borderline personality disorder traits (BPD traits) in early adulthood. The participants were 2,808 twins between 17 and 23 years from the Oslo University Adolescent and Young Adult Twin Project. BPD traits were assessed by the Structured Interview for DSM-IV Personality (SIDP-IV), and CT was assessed using the Childhood Trauma Interview (CTI). BPD traits (h² = .50) and CT (h² = .33-.69) were both found to be moderately heritable. Small but statistically significant associations between CT and BPD traits were found in the total sample. After controlling for shared environmental and genetic factors in the discordant twin pairs, the analyses showed little to no evidence for causal effects of CT on BPD traits. The results indicated that the associations between CT and BPD traits stem from common genetic influences. These findings are inconsistent with the widely held assumption that CT causes the development of BPD. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Severity of anabolic steroid dependence, executive function, and personality traits in substance use disorder patients in Norway.

INTRODUCTION: Anabolic androgenic steroids (AAS), including testosterone and synthetic derivatives, are typically used to increase muscle mass. Many users develop a dependence on these substances, contributing to worsened physical and mental health outcomes. Aspects of personality and executive dysfunction may represent underlying vulnerabilities for developing dependence. OBJECTIVE: To identify levels of AAS dependence within substance use disorder (SUD) treatment patients and assess the relationship between dependence severity and personality traits and executive function (EF). METHODS: Data were collected from patients at 38 SUD treatment facilities in Norway. Questionnaires were completed for measures of personality and EF. Measures of symptoms of AAS dependence were used in latent class analysis to identify sub-groups of patients, which were evaluated for association with EF and personality traits, and compared with a group of non-AAS using SUD patients. RESULTS: Three classes were identified; largely reflecting low, moderate, and high symptoms of dependence. Multinomial regression analyses indicated that moderate and high symptoms were associated with several measures of EF and personality traits, particularly self-monitoring, antagonism, disinhibition, and rigid perfectionism while users with low symptoms exhibited higher capacities for emotional control and shift, and lower negative affectivity, relative to non-AAS using SUD patients. Backward stepwise regressions indicated antagonism, and decreased self-monitoring as key personality and cognitive characteristics of SUD patients with severe AAS dependence. CONCLUSION: Our findings indicate that specific executive dysfunctions and personality features, particularly those associated with poor emotional control, reduced empathy, and impulsivity are associated with more severe AAS dependence in the SUD population.

The Oslo University Adolescent and Young Adult Twin Project: Recruitment and Attrition.

The Oslo University Adolescent and Young Adult Twin Project started in 2006 with the first of three questionnaire data collection waves, 2 years apart. All twins from the birth cohorts 1988-1994 were invited to participate, and both the twins and their parents were asked to sign consent forms. The twins were 12-18 years old at Wave 1, at which time parents were asked to complete similar questionnaires. The parents' questionnaire enquired about the parents' ratings of their twin's traits. In addition, the parents answered questions regarding their own education, demographics and socioeconomic situation. When the twins were 18 years old, they were invited to a face-to-face interview and two new questionnaires were presented. The questionnaires for the waves included a number of personality scales, internalization and externalization traits, affective and behavioral problems, as well as measures of environment and coping. The most common DSM-IV mental disorders and all personality disorders were covered in the interview. Zygosity was established both by questionnaire and gene markers. The original sample consisted of 5374 twin families, and among these, 4668 pairs were alive and living in Norway. Of these, 2486 families (53.3%) consented to participate. Of these, again 1538 twin families (61.9%) actually participated in at least one wave and twins from 1422 pairs (57.3%) participated in the interview. Female gender, but not zygosity, predicted staying in the project. Moreover, having a planning, structured personality (being more conscientious, open to experience [i.e., curious and interested in learning], having higher resilience and better school habits) increased the chance of carrying on in the project. Interestingly, the attrition did not seem to bias the heritability estimates.

Etiological influences on continuity and co-occurrence of eating disorders symptoms across adolescence and emerging adulthood.

OBJECTIVE: The role of common and symptom-specific genetic and environmental influences in maintaining eating disorder symptoms across development remains unclear. This study investigates the continuity and change of etiological influences on drive for thinness, bulimia, and body dissatisfaction symptoms and their co-occurrence, across adolescence and emerging adulthood. METHOD: In total, 2,629 adolescent twins (mean age = 15.20, SD = 1.95) reported eating disorders symptoms across three waves of data collection. Biometric common pathways model was fitted to estimate genetic and environmental contributions to the continuity of each symptom over time, as well as time- and symptom-specific influences. RESULTS: Drive for thinness and body dissatisfaction symptoms showed a pattern of high continuity across development and high correlations with each other, whereas bulimia symptoms were moderately stable and less associated with the other two symptoms. Latent factors reflecting continuity of each symptom were largely under genetic influence (Al = 0.60-0.82). New genetic influences contributing to change in the developmental course of symptoms were observed in emerging adulthood. Genetic influences correlated considerably between the three symptoms. Non-shared environmental influences were largely time-and symptom-specific, but some contributed moderately to the continuity across development (El = 0.18-0.40). The etiological overlap was larger between drive for thinness and body dissatisfaction symptoms than with bulimia symptoms. DISCUSSION: The results provide preliminary evidence that stable as well as newly emerging genetic influences contribute to the co-occurrence of drive for thinness, bulimia, and body dissatisfaction symptoms across adolescence and emerging adulthood. Conversely, environmental influences were less stable and contributed to change in symptoms over time.

Associations of children's Big Five personality with eating behaviors.

OBJECTIVE: Our aim is to examine the associations of the Big Five personality factors with eating behaviors in children using a cross-sectional study in 1543 randomly Norwegian 7-12 year olds. RESULTS: Mothers rated the hierarchical personality inventory for children, and the child eating behaviour questionnaire to describe her child. Personality and eating behaviors were substantially associated in bivariate correlations and multivariate analyses of variance. The strongest predictors of eating behaviors were neuroticism, followed by agreeableness and conscientiousness. Neuroticism correlated the highest with slow eating, emotional undereating, food responsiveness, and emotional overeating, and showed minor associations with satiety responsiveness, and fussiness. Neuroticism was not associated with enjoyment of food. Agreeableness was associated with low fussiness, low emotional undereating, low food responsiveness and low emotional overeating, conscientiousness was associated with low satiety responsiveness, and food responsiveness, and extraversion and imagination were associated with high enjoyment of food.

Interrater Reliability of the Structured Clinical Interview for the DSM-5 Alternative Model of Personality Disorders Module i: Level of Personality Functioning Scale.

The fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) presents an alternative model for personality disorders in which severity of personality pathology is evaluated by the Level of Personality Functioning Scale (LPFS). The Structured Interview for the DSM-5 Alternative Model for Personality Disorders, Module I (SCID-5-AMPD I) is a new tool for LPFS assessment, but its interrater reliability (IRR) has not yet been tested. Here we examined the reliability of the Norwegian translation of the SCID-5-AMPD I, applying two different designs: IRR assessment based on ratings of 17 video-recorded SCID-5-AMPD I interviews by five raters; and test-retest IRR based on interviews of 33 patients administered by two different raters within a short interval. For the video-based investigation, intraclass correlation coefficient (ICC) values ranged from .77 to .94 for subdomains, .89 to .95 for domains, and .96 for total LPFS. For the test-retest investigation, ICC ranged from .24 to .72 for subdomains, .59 to .90 for domains, and .75 for total LPFS. The test-retest study revealed questionable reliability estimates for some subdomains. However, overall the level of personality functioning was measured with a sufficient degree of IRR when assessed by the SCID-5-AMPD I.

Borderline personality disorder.

Caretakers are often intimidated or alienated by patients with borderline personality disorder (BPD), compounding the clinical challenges posed by the severe morbidity, high social costs and substantial prevalence of this disorder in many health-care settings. BPD is found in ∼1.7% of the general population but in 15-28% of patients in psychiatric clinics or hospitals and in a large proportion of individuals seeking help for psychological problems in general health facilities. BPD is characterized by extreme sensitivity to perceived interpersonal slights, an unstable sense of self, intense and volatile emotionality and impulsive behaviours that are often self-destructive. Most patients gradually enter symptomatic remission, and their rate of remission can be accelerated by evidence-based psychosocial treatments. Although self-harming behaviours and proneness to crisis can decrease over time, the natural course and otherwise effective treatments of BPD usually leave many patients with persistent and severe social disabilities related to depression or self-harming behaviours. Thus, clinicians need to actively enquire about the central issues of interpersonal relations and unstable identity. Failure to correctly diagnose patients with BPD leads to misleading pharmacological interventions that rarely succeed. Whether the definition of BPD should change is under debate that is linked to not fully knowing the nature of this disorder.

Emotional Lability in Preschoolers With Symptoms of ADHD.

OBJECTIVE: The aim of this study was to examine occurrence of emotional lability (EL) in preschoolers with ADHD symptoms versus controls. METHOD: The study was part of the Norwegian Mother and Child Cohort Study (MoBa) at the Norwegian Institute of Public Health. In the present study, 495 preschoolers were clinically examined. Symptoms of ADHD, anxiety, and oppositional defiant disorder (ODD) were measured with the Preschool Age Psychiatric Assessment Interview. An EL measure was obtained from the Emotional Control subscale of the Behavior Rating Inventory of Executive Function-Preschool Version (BRIEF-P), which parents and teachers completed. RESULTS: EL was significantly more frequent in the ADHD group compared with controls (25% vs. 7%, p < .001). By parent report, EL correlated significantly with ADHD-, anxiety-, and ODD symptoms. By teacher report, EL was significantly correlated only with hyperactivity-impulsivity. CONCLUSION: EL appears identifiable in young preschoolers and was particularly associated with ODD in children with ADHD symptoms.

The genetic and environmental architecture of substance use development from early adolescence into young adulthood: a longitudinal twin study of comorbidity of alcohol, tobacco and illicit drug use.

AIMS: To investigate how use of alcohol, illicit drugs and tobacco come from substance-specific pathways and from pathways general to all three substances through adolescent development. DESIGN: Analysis of population-based survey. Adolescent twins reported alcohol use (AU), tobacco use (TU) and illicit drug use (IDU) in three waves (2006, 2008, 2010). Restructuring data by age allowed for variance decomposition into age- and substance-specific and common genetic and environmental variance components. SETTING: Norway. PARTICIPANTS: Seven national twin birth cohorts from 1988 to 1994, totalling 1483 pairs (558 monozygotic; 925 dizygotic, same and opposite sex). MEASUREMENTS: Six-point Likert scores of AU, TU and IDU on items from the Monitoring the Future Study. FINDINGS: Substance use was found to be highly heritable; a2  = 0.73 [95% confidence interval (CI) = 0.61-0.94] for AU, a2  = 0.36 (CI = 0.18-0.52); d2  = 0.49 (95% CI = 0.29-0.62) for IDU and a2  = 0.46 (95% CI = 0.23-0.54); d2  = 0.05 (95% CI = 0.00-0.07) for TU during the whole adolescence period. General substance use (GSU) was also highly heritable at each age and averaged a2  = 0.57 (95% CI = 0.48-0.66). There was a high genetic carry-over from earlier age to later age. Genetic effects on GSU at ages 12-14 years were still detectable 4 years later. New substance (general and specific)-genetic effects also appeared. IDU demonstrated significant non-additive genetic effects (ages 12-14 years). Shared environment had a small impact on AU only. There was almost no non-shared environmental carry-over from age to age, the effect probably due partly to reliability deficiency. Common genetic effects among substance and substance-specific genetic effects were observed at each age-period. CONCLUSIONS: Among Norwegian adolescents, there appear to be strong genetic effects on both substance-specific and comorbid use of alcohol, illicit drugs and tobacco; individual differences in alcohol use can be explained partially by family background.

Personality disorders and Axis I comorbidity in adolescent outpatients with ADHD.

BACKGROUND: Attention deficit hyperactivity disorder (ADHD) is a lifelong condition which carries great cost to society and has an extensive comorbidity. It has been assumed that ADHD is 2 to 5 times more frequent in boys than in girls. Several studies have suggested developmental trajectories that link ADHD and certain personality disorders. The present study investigated the prevalence of ADHD, common Axis I disorders, and their gender differences in a sample of adolescent outpatients. We also wanted to investigate the relationship between ADHD and personality disorders (PDs), as well as how this relationship was influenced by adjustment for Axis I disorders, age and gender. METHODS: We used a sample consisting of 153 adolescents, aged 14 to 17 years, who were referred to a non-specialized mental health outpatient clinic with a defined catchment area. ADHD, conduct disorder (CD) and other Axis I conditions were assessed using the Mini International Neuropsychiatric Interview (MINI). PDs were assessed using the Structured Interview for DSM-IV Personality (SIDP-IV). RESULTS: 13.7 % of the adolescents met diagnostic criteria for ADHD, with no significant gender difference. 21.6 % had at least one PD, 17.6 % had CD, and 4.6 % had both ADHD and a PD. There was a significantly elevated number of PD symptoms in adolescents with an ADHD diagnosis (p = 0.001), and this relationship was not significantly weakened when adjusted for age, gender and other Axis I disorders (p = 0.026). Antisocial (χ (2) = 21.18, p = 0.002) and borderline (χ (2) = 6.15, p = 0.042) PDs were significantly more frequent in girls than in boys with ADHD. CONCLUSIONS: We found no significant gender difference in the prevalence of ADHD in a sample of adolescents referred to a general mental health outpatient clinic. Adolescent girls with ADHD had more PDs than boys, with antisocial and borderline PDs significantly different. The present study suggests that ADHD in girls in a general outpatient population may be more prevalent than previously assumed. It especially highlights the importance of assessing antisocial and borderline personality pathology in adolescent girls presenting with ADHD symptoms.

Substance abuse and personality disorder comorbidity in adolescent outpatients: are girls more severely ill than boys?

BACKGROUND: Substance use disorders (SUDs) constitute a major health problem and are associated with an extensive psychiatric comorbidity. Personality disorders (PDs) and SUDs commonly co-occur. Comorbid PD is characterized by more severe addiction problems and by an unfavorable clinical outcome. The present study investigated the prevalence of SUDs, PDs and common Axis I disorders in a sample of adolescent outpatients. We also investigated the association between PDs and SUDs, and how this association was influenced by adjustment for other Axis I disorders, age and gender. METHODS: The sample consisted of 153 adolescents, aged 14-17 years, who were referred to a non-specialized mental health outpatient clinic with a defined catchment area. SUDs and other Axis I conditions were assessed using the mini international neuropsychiatric interview. PDs were assessed using the structured interview for DSM-IV personality. RESULTS: 18.3 % of the adolescents screened positive for a SUD, with no significant gender difference. There was a highly significant association between number of PD symptoms and having one or more SUDs; this relationship was practically unchanged by adjustment for gender, age and presence of Axis I disorders. For boys, no significant associations between SUDs and specific PDs, conduct disorder (CD) or attention deficit hyperactivity disorder (ADHD) were found. For girls, there were significant associations between SUD and BPD, negativistic PD, more than one PD, CD and ADHD. CONCLUSIONS: We found no significant gender difference in the prevalence of SUD in a sample of adolescents referred to a general mental health outpatient clinic. The association between number of PD symptoms and having one or more SUDs was practically unchanged by adjustment for gender, age and presence of one or more Axis I disorders, which suggested that having an increased number of PD symptoms in itself may constitute a risk factor for developing SUDs in adolescence. The association in girls between SUDs and PDs, CD and ADHD raises the question if adolescent girls suffering from these conditions may be especially at risk for developing SUDs. In clinical settings, they should therefore be monitored with particular diligence with regard to their use of psychoactive substances. Trial registration The regional committee for medical research ethics for eastern Norway approved the study protocol in October 2004 (REK: 11395). Address correspondence and reprint requests to: Hans Ole Korsgaard, The Nic Waal Institute, Lovisenberg Diakonale Hospital, P.O. Box 2970 Nydalen, N-0440 Oslo, Norway; E-mail hansole.korsgaard@tele5.no.

Constructing a short form of the hierarchical personality inventory for children (HiPIC): the HiPIC-30.

Children's personality traits are invaluable predictors of concurrent and later mental and physical health. Several validated longer inventories for assessing the widely recognized Five-Factor Model of personality in children are available, but short forms are scarce. This study aimed at constructing a 30-item form of the 144-item Hierarchical Personality Inventory for Children (HiPIC) (Mervielde & De Fruyt, ). Participants were 1543 children aged 6-12 years (sample 1) and 3895 children aged 8 years (sample 2). Sample 1 completed the full HiPIC, from which we constructed the HiPIC-30, and the Child Behaviour Checklist (Achenbach, ). Sample 2 completed the HiPIC-30. The HiPIC-30 personality domains correlated over r = .90 with the full HiPIC domains, had good Cronbach's alphas and correlated similarly with CBCL behaviour problems and gender as the full HiPIC. The factor structures of the HiPIC-30 were convergent across samples, but the imagination factor was not clear-cut. We conclude that the HiPIC-30 is a reliable and valid questionnaire for the Five-Factor personality traits in children. Copyright © 2016 John Wiley & Sons, Ltd.

Sex differences in genetic and environmental contributions to alcohol consumption from early adolescence to young adulthood.

AIMS: To estimate genetic and environmental contributions to alcohol consumption from early adolescence to young adulthood, and test whether gender moderates these effects. DESIGN: Longitudinal twin cohort design. SETTING: Population-based sample from Norway. PARTICIPANTS: A total of 2862 male and female twins, aged 14-22 years, were assessed at one (n = 881), two (n = 898) or three (n = 1083) occasions. The percentage of females was between 56 and 63 in the different age groups (in the different waves). MEASUREMENTS: Alcohol consumption was measured by two questionnaire items about frequency of alcohol use and frequency of being drunk. FINDINGS: Additive genetic effects showed low to moderate contributions [proportion estimate, 95% confidence interval (CI) = range from 0.03 (0.00-0.14) to 0.49 (0.37-0.59) in males and from 0.09 (0.00-0.57) to 0.41 (0.24-0.58) in females] from adolescence to young adulthood, while environmental influences shared by twin pairs and contributing to twin similarity were moderate to highly influential during this developmental period [proportion estimate, 95% CI = range from 0.04 (0.00-0.13) to 0.45 (0.26-0.60) in males for shared environment in common with females, from 0.25 (0.09-0.42) to 0.54 (0.06-0.78) for shared environment specific to males and from 0.36 (0.20-0.52) to 0.51 (0.37-0.71) in females]. There was evidence of qualitative sex differences with shared environmental influences being largely sex-specific from middle adolescence onwards. CONCLUSIONS: Alcohol consumption from early adolescence to young adulthood appears to be influenced to a small to moderate degree by genetic factors and to a moderate to high degree by shared environmental factors (e.g. rearing influences, shared friends). The shared environmental factors influencing alcohol consumption appear to be largely gender-specific.

Common Etiological Sources of Anxiety, Depression, and Somatic Complaints in Adolescents: A Multiple Rater twin Study.

Somatic complaints in children and adolescents may be considered part of a broader spectrum of internalizing disorders that include anxiety and depression. Previous research on the topic has focused mainly on the relationship between anxiety and depression without investigating how common somatic symptoms relate to an underlying factor and its etiology. Based on the classical twin design with monozygotic and dizygotic twins reared together, our study aimed to explore the extent to which the covariation between three phenotypes in adolescent girls and boys can be represented by a latent internalizing factor, with a focus on both common and specific etiological sources. A population-based sample of twins aged 12-18 years and their mothers and fathers (N = 1394 families) responded to questionnaire items measuring the three phenotypes. Informants' ratings were collapsed using full information maximum likelihood estimated factor scores. Multivariate genetic analyses were conducted to examine the etiological structure of concurrent symptoms. The best fitting model was an ACE common pathway model without sex limitation and with one substantially heritable (44%) latent factor shared by the phenotypes. Concurrent symptoms also resulted from shared (25%) and non-shared (31%) environments. The factor loaded most on depression symptoms and least on somatic complaints. Trait-specific influences explained 44% of depression variance, 59% of anxiety variance, and 65% of somatic variance. Our results suggest the presence of a general internalizing factor along which somatic complaints and mental distress can be modeled. However, specific influences make the symptom types distinguishable.