| 1. |
- Taylor, M. J., et al.
(författare)
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Is There a Female Protective Effect Against Attention-Deficit/Hyperactivity Disorder? Evidence From Two Representative Twin Samples
- 2016
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Ingår i: Journal of the American Academy of Child and Adolescent Psychiatry. - Stockholm : Elsevier BV. - 0890-8567 .- 1527-5418. ; 55:6, s. 504-512
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Tidskriftsartikel (refereegranskat)abstract
- Objective: Attention-deficit/hyperactivity disorder (ADHD) is more frequent in males than in females. The "female protective effect" posits that females undergo greater exposure to etiological factors than males in order to develop ADHD, leading to the prediction that relatives of females with ADHD will display more ADHD behaviors. We thus tested whether cotwins of females displaying extreme ADHD traits would display more ADHD traits than cotwins of males displaying extreme ADHD traits. Method: Parents of approximately 7,000 pairs of nonidentical twins in Sweden, and approximately 4,000 pairs of twins in England and Wales, completed dimensional assessments of ADHD traits. Probands were selected on the basis of scoring within the highest 10% of the distribution in each sample. Dimensional scores of cotwins of probands, as well as the categorical recurrence rate, were investigated by proband sex. Results: Cotwins of female probands displayed higher mean ADHD trait scores (mean = 0.62-0.79) than cotwins of male probands (mean = 0.38-0.55) in both samples. This trend was significant in the Swedish sample (p <.01) and when the 2 samples were merged into a single, larger sample (p <.001). When the samples were merged, there was also a significant association between proband sex and cotwin's categorical status, with more cotwins of female probands also being probands than cotwins of male probands. Conclusion: These findings support a female protective effect against ADHD behaviors, suggesting that females require greater exposure to genetic and environmental factors associated with ADHD in order to develop the condition.
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| 2. |
- Bolhuis, Koen, et al.
(författare)
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Disentangling Heterogeneity of Childhood Disruptive Behavior Problems Into Dimensions and Subgroups
- 2017
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Ingår i: Journal of the American Academy of Child and Adolescent Psychiatry. - : Elsevier. - 0890-8567 .- 1527-5418. ; 56:8, s. 678-686
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Tidskriftsartikel (refereegranskat)abstract
- Objective: Irritable and oppositional behaviors are increasingly considered as distinct dimensions of oppositional defiant disorder. However, few studies have explored this multidimensionality across the broader spectrum of disruptive behavior problems (DBPs). This study examined the presence of dimensions and distinct subgroups of childhood DBPs, and the cross-sectional and longitudinal associations between these dimensions.Method: Using factor mixture models (FMMs), the presence of dimensions and subgroups of DBPs was assessed in the Generation R Study at ages 6 (n = 6,209) and 10 (n = 4,724) years. Replications were performed in two population-based cohorts (Netherlands Twin Registry, n = 4,402, and Swedish Twin Study of Child and Adolescent Development, n = 1,089) and a clinical sample (n = 1,933). We used cross-lagged modeling in the Generation R Study to assess cross-sectional and longitudinal associations between dimensions. DBPs were assessed using mother-reported responses to the Child Behavior Checklist.Results: Empirically obtained dimensions of DBPs were oppositional behavior (age 6 years), disobedient behavior, rule-breaking behavior (age 10 years), physical aggression, and irritability (both ages). FMMs suggested that one-class solutions had the best model fit for all dimensions in all three population-based cohorts. Similar results were obtained in the clinical sample. All three dimensions, including irritability, predicted subsequent physical aggression (range, 0.08-0.16).Conclusion: This study showed that childhood DBPs should be regarded as a multidimensional phenotype rather than comprising distinct subgroups. Incorporating multidimensionality will improve diagnostic accuracy and refine treatment. Future studies need to address the biological validity of the DBP dimensions observed in this study; herein lies an important opportunity for neuro-imaging and genetic measures.
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| 3. |
- Brikell, Isabell, et al.
(författare)
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Relative Immaturity in Childhood and Attention-Deficit/Hyperactivity Disorder Symptoms From Childhood to Early Adulthood : Exploring Genetic and Environmental Overlap Across Development
- 2016
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Ingår i: Journal of the American Academy of Child and Adolescent Psychiatry. - : Elsevier. - 0890-8567 .- 1527-5418. ; 55:10, s. 886-895
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Tidskriftsartikel (refereegranskat)abstract
- Objective: Attention-deficit/hyperactivity disorder (ADHD) has been linked to immaturity relative to peers in childhood, yet it is unclear how such immaturity is associated with ADHD across development. This longitudinal twin study examined the genetic and environmental contributions to the association between parents' perception of their child's immaturity relative to peers (RI) in childhood and ADHD symptoms across development.Method: 1,302 twin pairs from the Swedish Twin Study of Child and Adolescent Development were followed prospectively from childhood to early adulthood. Parent ratings of RI were collected at 8 to 9 years and parent and self-ratings of ADHD symptoms were collected at 8 to 9, 13 to 14, 16 to 17, and 19 to 20 years using the Child Behavior Checklist Attention Problems scale. In addition, ADHD symptoms corresponding to DSM criteria were used for sensitivity analysis. Analyses were conducted using longitudinal structural equation modeling with multiple raters.Results: RI-related etiologic factors, predominantly influenced by genes, explained 10-14% of the variance in ADHD symptoms from 8 to 9 up to 16 to 17 years. The influence of these RI-related factors on ADHD symptoms attenuated to 4% by 19 to 20 years of age. The remaining variance in ADHD symptoms was primarily explained by genetic factors independent of RI, which remained relatively stable across development, explaining 19% to 30% of the variance in ADHD symptoms from 13 to 14 up to 19 to 20 years.Conclusion: The results show that RI is significantly associated with ADHD symptoms, particularly during childhood and adolescence, and that the association is primarily explained by a shared genetic liability. Nevertheless, the magnitude of associations across development was modest, highlighting that RI is merely one aspect contributing to the complex etiology of ADHD symptoms.
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| 4. |
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| 5. |
- Colins, Olivier F., et al.
(författare)
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The Prognostic Usefulness of Multiple Specifiers for Subtyping Conduct Problems in Early Childhood
- 2023
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Ingår i: Journal of the American Academy of Child and Adolescent Psychiatry. - : Elsevier. - 0890-8567 .- 1527-5418. ; 62:10S, s. S160-S161
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Objectives: Better descriptions and treatment of children with conduct problems (CP) grandiose-manipulative (GM) and daring-impulsive (DI) traits are proposed for subtyping CP, instead of only using a callous-unemotional (CU) specifier. Unfortunately, the acclaimed benefits of having multiple specifiers for CP remain largely untested and, therefore, highly speculative. To fill this gap, we tested longitudinal relations between these 3 specifiers and developmental outcomes in childhood and adolescence, independent of early childhood CP.Methods: We relied on longitudinal data from 2 community studies. Teacher-ratings were used to measure CP and the specifiers in 3- to 5-year-olds from Sweden (N = 2064) and Spain (N = 2055). Developmental outcomes were assessed by multiple informants (ie, teachers, parents, and children) 1 to 8 years later.Results: Early childhood CP were predictive of all outcomes. CU traits predicted low levels of social competence and prosocial behavior, independent of CP (and age, gender, and socioeconomic status). GM and DI traits were predictive of aggression and violent delinquency, respectively, independent of CP, but also of higher levels of prosocial behavior or social competence.Conclusions: The 3 specifiers are predictive of different outcomes, independent of CP, which is thought to form the basis for developing specifiers for CP. Findings tentatively challenge the centrality of CU traits for subtyping CP, but it is premature to conclude that GM and DI specifiers are needed in future revisions of the DSM and ICD. Efforts to systematically evaluate the utility of these specifiers should be welcomed to inform ongoing debates on this matter.
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| 6. |
- Faraone, Stephen V., et al.
(författare)
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The Familial Co-Aggregation of Attention-Deficit/Hyperactivity Disorder and Intellectual Disability : A Register-Based Family Study
- 2017
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Ingår i: Journal of the American Academy of Child and Adolescent Psychiatry. - : Elsevier. - 0890-8567 .- 1527-5418. ; 56:2, s. 167-174.e1
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Tidskriftsartikel (refereegranskat)abstract
- Objective: Although many studies document an association between attention-deficit/hyperactivity disorder (ADHD) and intellectual disability (ID), little is known about the etiology of this comorbidity and how it should be addressed in clinical settings. We sought to clarify this issue.Method: All individuals born in Sweden between 1987 and 2006 (n = 2,049,587) were identified using the Medical Birth Register (MBR). From this we selected 7 cohorts of relatives: 1,899,654 parent-offspring pairs, 4,180 monozygotic twin pairs, 12,655 dizygotic twin pairs, 914,848 full sibling pairs, 136,962 maternal half-sibling pairs, 134,502 paternal half-sibling pairs, and 2,790,164 full cousin pairs. We used within-individual and within-family analyses to assess the association between ADHD and ID.Results: Individuals with ID were at increased risk for ADHD compared to those without ID, and relatives of participants with ID were at increased risk of ADHD compared with relatives of those without ID. The magnitude of this association was positively associated with the fraction of the genome shared by the relative pair and was lower for severe compared with mild and moderate ID. Model-fitting analyses demonstrated that 91% of the correlation between the liabilities of ADHD and ID was attributable to genetic factors.Conclusion: These data provide evidence that nearly all of the comorbidity between ADHD and ID can be attributed to genetic factors, which has implications for diagnostic practice.
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| 7. |
- Hultman, Christina, et al.
(författare)
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Birth weight and attention-deficit/hyperactivity symptoms in childhood and early adolescence : A prospective Swedish twin study
- 2007
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Ingår i: Journal of the American Academy of Child and Adolescent Psychiatry. - : Elsevier BV. - 0890-8567 .- 1527-5418. ; 46:3, s. 370-377
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: To determine whether low birth weight increases the risk of attention-deficit/hyperactivity disorder (ADHD) in childhood and early adolescence. METHOD: In a population-based sample of 1,480 twin pairs born in the period 1985-1986 ascertained from the Swedish Twin Registry, birth weight was collected prospectively through the Medical Birth Registry. ADHD symptoms were measured with a 14-item checklist covering DSM-III-R criteria (parental rating) at age 8 to 9 years and 13 to 14 years. We used both a dichotomous approach for birth weight (>400 g or 15% weight difference) and ADHD (eight or more symptoms) and continuous measures to investigate between- and within-twin pair effects. RESULTS: Our results showed that low birth weight was a risk factor for symptoms of ADHD and the associations did not diminish when we controlled for genetic influence. The lighter twin in birth weight-discordant pairs had on average 13% higher ADHD symptom score at age 8 to 9 years (p = .006) and 12% higher ADHD score at age 13 to 14 years (p = .018) compared with the heavier twin. The genetic correlations suggest modest or no genetic overlap between birth weight and ADHD. CONCLUSIONS: The hypothesis that low birth weight is associated with the development of ADHD symptoms was supported in this prospective twin study. Fetal growth restriction seems to represent a modest but fairly consistent environmental influence on the development of ADHD symptoms.
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| 8. |
- Khalife, Natasha, et al.
(författare)
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Childhood Attention-Deficit/Hyperactivity Disorder Symptoms Are Risk Factors for Obesity and Physical Inactivity in Adolescence
- 2014
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Ingår i: Journal of the American Academy of Child and Adolescent Psychiatry. - : Elsevier BV. - 0890-8567 .- 1527-5418. ; 53:4, s. 425-436
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Tidskriftsartikel (refereegranskat)abstract
- Objective: To prospectively investigate the association and directionality between attention-deficit/hyperactivity disorder (ADHD) symptoms and obesity from childhood to adolescence in the general population. We examined whether obesogenic behaviors, namely, physical inactivity and binge eating, underlie the potential ADHD symptom obesity association. We explored whether childhood conduct disorder (CD) symptoms are related to adolescent obesity/physical inactivity. Method: At 7 to 8 years (n = 8,106), teachers reported ADHD and CD symptoms, and parents reported body mass index (BMI) and physically active play. At 16 years (n = 6,934), parents reported ADHD symptoms; adolescents reported physical activity (transformed to metabolic equivalent of task [MET] hours per week) and binge eating; BMI and waist hip ratio (WHR) were measured via clinical examination. Obesity was defined using the International Obesity Task Force (IOTF) cut-offs for BMI and the 95th percentile cut-off for WHR. Results: Childhood ADHD symptoms significantly predicted adolescent obesity, rather than the opposite. Inattention-hyperactivity symptoms at 8 years were associated with indices of obesity at 16 years (obese BMI: odds ratio [OR] = 1.91, 95% confidence interval [CI] = 1.10-3.33; 95th percentile WHR: OR = 1.71, 95% CI = 1.05-2.78), adjusted for gender, baseline BMI, physical activity, family structure change, and maternal education. Child CD symptoms associated with indices of adolescent obesity. Reduced physically active play in childhood predicted adolescent inattention (OR = 1.61,95% CI = 1.16-2.24). Childhood ADHD and CD symptoms were linked with physical inactivity in adolescence (inattention-hyperactivity; OR = 1.60, 95% CI = 1.20-2.13), but not binge eating. Physical inactivity mediated the associations. Conclusions: Children with ADHD or CD symptoms are at increased risk for becoming obese and physically inactive adolescents. Physical activity may be beneficial for both behavior problems and obesity.
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| 9. |
- Larsson, Henrik, 1975-, et al.
(författare)
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Genetic contributions to the development of ADHD subtypes from childhood to adolescence
- 2006
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Ingår i: Journal of the American Academy of Child and Adolescent Psychiatry. - : Lippincott Williams & Wilkins. - 0890-8567 .- 1527-5418. ; 45:8, s. 973-981
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVES: Little is known about how genes influence the development of symptoms included in the DSM-IV subtypes of attention-deficit/hyperactivity disorder (ADHD) from childhood to adolescence. The aim of this study was to examine genetic influences contributing to the development of hyperactive-impulsive symptoms and inattentive symptoms of ADHD from childhood to adolescence.METHOD: The sample included all 1,480 twin pairs born in Sweden between May 1985 and December 1986. Parents responded to mailed questionnaires on three occasions, when the twins were 8 to 9, 13 to 14, and 16 to 17 years old. The authors used dimensional scales of hyperactivity-impulsivity and inattention derived from a checklist of items based on the DSM symptoms of ADHD.RESULTS: Symptoms of hyperactivity-impulsivity declined with increasing age, whereas there was no decline in symptoms of inattention. Persistent genetic influences explain between 45% and 90% of the total genetic variance in hyperactivity-impulsivity and inattention across age. Persistent genetic variance was primarily operating across subtypes, even though persistent subtype-specific influences were also significant.CONCLUSIONS: The finding of persistent cross-subtype (i.e., combined) and persistent subtype-specific genetic influences (i.e., primarily hyperactive-impulsive and primarily inattentive) are in line with a genetic basis for the DSM-IV classification of ADHD subtypes.
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| 10. |
- Larsson, Jan-Olov, et al.
(författare)
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Genetic and environmental contributions to stability and change of ADHD symptoms between 8 and 13 years of age : a longitudinal twin study
- 2004
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Ingår i: Journal of the American Academy of Child and Adolescent Psychiatry. - Philadelphia, USA : Lippincott Williams & Wilkins. - 0890-8567 .- 1527-5418. ; 43:10, s. 1267-1275
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Tidskriftsartikel (refereegranskat)abstract
- Objective: To study the genetic and environmental contributions to stability and change of attention-deficit/hyperactivity disorder (ADHD) symptoms between 8 and 9 and 13 and 14 years of age.Method: The sample included 1,480 twin pairs born in Sweden between May 1985 and December 1986. At wave 1 in 1994, when twins were 8-9 years old, 1,106 (75%) of the parents responded to a mailed questionnaire, and at wave 2 when the twins were 13-14 years old, 1,063 (73%) responded. A checklist with 14 items based on the 14 DSM-III-R symptoms for ADHD was completed. Structural equation modeling was used to analyze the data.Results: A relatively high stability of ADHD symptoms over this 5-year period was found. This continuity was mainly due to the same genetic effects operating at both points in time. Change in symptoms between childhood and early adolescence was to a large extent due to new genetic effects in early adolescence but also due to new nonshared environmental effects that became important during adolescence.Conclusions: The genetic stability highlights the importance of the continuing search for genes and endophenotypes of ADHD.
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