| 1. |
- Gustafsson, Per, et al.
(författare)
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Heritability of cortisol regulation in children.
- 2011
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Ingår i: Twin research and human genetics : the official journal of the International Society for Twin Studies. - : Australian Academic Press. - 1832-4274 .- 1839-2628. ; 14:6, s. 553-61
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Tidskriftsartikel (refereegranskat)abstract
- The normal development of cortisol regulation during childhood is thought to be influenced by a complex interplay between environmental and genetic factors.
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| 2. |
- Holmberg, K., et al.
(författare)
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Impact of asthma medication and familial factors on the association between childhood asthma and attention-deficit/hyperactivity disorder: a combined twin- and register-based study
- 2015
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Ingår i: Clinical and Experimental Allergy. - Stockholm : Wiley. - 0954-7894 .- 1365-2222. ; 45:5, s. 964-973
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Tidskriftsartikel (refereegranskat)abstract
- BackgroundAsthma and attention-deficit/hyperactivity disorder (ADHD) are prevalent in childhood and may cause functional impairment and stress in families. Previous research supports an association between asthma and ADHD in children, but several aspects of this relationship are unclear. ObjectiveOur aim was to study whether the association between asthma and ADHD is restricted to either the inattentive or the hyperactive/impulsive symptoms of ADHD, to explore the impact of asthma severity and asthma medication and the contribution of shared genetic and environmental risk factors on the asthma-ADHD relationship. MethodsData on asthma, ADHD, zygosity and possible confounders were collected from parental questionnaires at 9 or 12years on 20072 twins through the Swedish Twin Register, linked to the Swedish Medical Birth Register, the National Patient Register and the Prescribed Drug Register. The association between asthma and ADHD, the impact of asthma severity and medication, was assessed by generalized estimating equations. Cross-twin-cross-trait correlations (CTCT) were estimated to explore the relative importance of genes and environment for the association. ResultsAsthmatic children had a higher risk of also having ADHD [odds ratio (OR) 1.53, 95% confidence interval (CI): 1.16-2.02]. The association was not restricted to either of the two dimensions of ADHD. The magnitude of the association increased with asthma severity (OR 2.84, 95% CI: 1.86-4.35) for 4 asthma attacks in the last 12months and was not affected by asthma treatment. The CTCTs possibly indicate that the genetic component in overlap of the disorders is weak. Conclusions and Clinical RelevanceChildhood asthma, especially severe asthma, is associated with ADHD. Asthma medication seems not to increase the risk of ADHD. Clinicians should be aware of the potential of ADHD in asthma. Optimal asthma care needs to be integrated with effective evaluation and treatment of ADHD in children with co-existing disorders.
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| 3. |
- Jonsson, Lina, 1982, et al.
(författare)
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Association between ASMT and autistic-like traits in children from a Swedish nationwide cohort
- 2014
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Ingår i: Psychiatric Genetics. - Stockholm : Lippincott Williams & Wilkins. - 0955-8829 .- 1473-5873. ; 24:1, s. 21-27
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Tidskriftsartikel (refereegranskat)abstract
- Individuals with autism spectrum disorders often show low levels of melatonin, and it has been suggested that this decrease may be because of the low activity of the acetylserotonin O-methyltransferase (ASMT), the last enzyme in the melatonin-synthesis pathway. Also, genetic variants in ASMT have been associated with autism, as well as with low ASMT activity and melatonin levels, suggesting that the low ASMT activity observed in autism may partly be because of variations within the ASMT gene. In this study, we present a symptom-based approach to investigate possible associations between ASMT and autistic-like traits in the general population. To this end, continuous measures of autistic-like traits were assessed in a nationally representative twin cohort (n=1771) from Sweden and six single nucleotide polymorphisms (SNPs), and a duplication of exons 2-8 in ASMT were genotyped. Our results show a nominally significant association, in girls, between one single nucleotide polymorphism (rs5949028) in the last intron of ASMT and social interaction impairments. No significant association, however, was observed with traits related to language impairment or restricted and repetitive behavior. In conclusion, our results support the possible involvement of the ASMT gene in autism spectrum disorders, and our finding that only one of the three traits shows association suggests that genetic research may benefit from adopting a symptom-specific approach to identify genes involved in autism psychopathology.
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| 4. |
- Larsson, Henrik, 1975-, et al.
(författare)
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Childhood attention-deficit hyperactivity disorder as an extreme of a continuous trait: a quantitative genetic study of 8,500 twin pairs.
- 2012
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Ingår i: Journal of child psychology and psychiatry, and allied disciplines. - : Wiley. - 1469-7610 .- 0021-9630. ; 53:1, s. 73-80
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Tidskriftsartikel (refereegranskat)abstract
- Although the clinical utility of categorically defined attention-deficit hyperactivity disorder (ADHD) is well established, there is also strong evidence supporting the notion of ADHD as an extreme of a continuous trait. Nevertheless, the question of whether the etiology is the same for different levels of DSM-IV ADHD symptoms remains to be investigated. The aim of this study was to assess genetic links between the extreme and the subthreshold range of ADHD symptoms.
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| 5. |
- Lichtenstein, P., et al.
(författare)
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Associations between conduct problems in childhood and adverse outcomes in emerging adulthood: a longitudinal Swedish nationwide twin cohort
- 2020
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Ingår i: Journal of Child Psychology and Psychiatry and Allied Disciplines. - : Wiley. - 0021-9630 .- 1469-7610. ; 61:7, s. 798-806
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Tidskriftsartikel (refereegranskat)abstract
- Background We examined whether childhood conduct problems predicted a wide range of adverse outcomes in emerging adulthood and whether the association with internalizing problems remained after adjusting for general comorbidity and externalizing problems. Methods Participants were 18,649 twins from the Child and Adolescent Twin Study in Sweden. At age 9/12, parents rated their children on eight conduct problems. Adverse outcomes were retrieved from national registers in emerging adulthood (median follow‐up time = 9.2 years), including diagnoses of six psychiatric disorders, prescriptions of antidepressants, suicide attempts, criminality, high school ineligibility, and social welfare recipiency. We estimated risk for the separate outcomes and examined if conduct problems predicted an internalizing factor above and beyond a general comorbidity and an externalizing factor. We used twin analyses to estimate genetic and environmental contributions to these associations. Results On the average, each additional conduct symptom in childhood was associated with a 32% increased risk of the adverse outcomes in emerging adulthood (mean hazard ratio = 1.32; range = 1.16, 1.56). A latent childhood conduct problems factor predicted the internalizing factor in emerging adulthood (βboys = .24, standard error, SE = 0.03; βgirls = .17, SE = 0.03), above and beyond its association with the externalizing (βboys = 0.21, SE = 0.04; βgirls = 0.17, SE = 0.05) and general factors (βboys = 0.45, SE = 0.03; βgirls = 0.34, SE = 0.04). These associations were differentially influenced by genetic and environmental factors. Conclusions It is important to monitor boys and girls with conduct problems not only for future externalizing problems, but also for future internalizing problems. Prevention of specific outcomes, however, might require interventions at different levels.
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| 6. |
- Lundström, Sebastian, et al.
(författare)
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Autism spectrum disorders and autistic like traits: similar etiology in the extreme end and the normal variation.
- 2012
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Ingår i: Archives of General Psychiatry. - Chicago, USA : American Medical Association (AMA). - 0003-990X .- 1538-3636. ; 69:1, s. 46-52
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Tidskriftsartikel (refereegranskat)abstract
- CONTEXT: Autism spectrum disorders (ASDs) have been suggested to represent the extreme end of a normal distribution of autisticlike traits (ALTs). However, the evidence of this notion is inconclusive. OBJECTIVE: To study whether there are similar genetic and/or environmental etiologies behind ASDs and ALTs. DESIGN: A nationwide twin study. PARTICIPANTS: Consenting parents of all Swedish twins aged 9 and 12 years, born between July 1, 1992, and December 31, 2001 (n = 19 208), were interviewed by telephone to screen for child psychiatric conditions, including ASDs. MAIN OUTCOME MEASURES: Two validated cutoffs for ASDs, 2 cutoffs encompassing the normal variation, and 1 continuous measure of ALTs were used with DeFries-Fulker extreme-end analyses and standard twin study methods. RESULTS: We discerned a strong correlation between the 4 cutoffs and the full variation of ALTs. The correlation was primarily affected by genes. We also found that the heritability for the 4 cutoffs was similar. CONCLUSION: We demonstrate an etiological similarity between ASDs and ALTs in the normal variation and, with results from previous studies, our data suggest that ASDs and ALTs are etiologically linked.
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| 7. |
- Magnusson, Patrik K. E., et al.
(författare)
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The Swedish Twin Registry : establishment of a biobank and other recent developments
- 2013
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Ingår i: Twin Research and Human Genetics. - Cambridge, United Kingdom : Cambridge University Press. - 1832-4274 .- 1839-2628. ; 16:1, s. 317-329
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Tidskriftsartikel (refereegranskat)abstract
- The Swedish Twin Registry (STR) today contains more than 194,000 twins and more than 75,000 pairs have zygosity determined by an intra-pair similarity algorithm, DNA, or by being of opposite sex. Of these, approximately 20,000, 25,000, and 30,000 pairs are monozygotic, same-sex dizygotic, and opposite-sex dizygotic pairs, respectively. Since its establishment in the late 1950s, the STR has been an important epidemiological resource for the study of genetic and environmental influences on a multitude of traits, behaviors, and diseases. Following large investments in the collection of biological specimens in the past 10 years we have now established a Swedish twin biobank with DNA from 45,000 twins and blood serum from 15,000 twins, which effectively has also transformed the registry into a powerful resource for molecular studies. We here describe the main projects within which the new collections of both biological samples as well as phenotypic measures have been collected. Coverage by year of birth, zygosity determination, ethnic heterogeneity, and influences of in vitro fertilization are also described.
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| 8. |
- Pettersson, Erik, et al.
(författare)
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Birth weight as an independent predictor of ADHD symptoms : a within-twin pair analysis
- 2015
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Ingår i: Journal of Child Psychology and Psychiatry. - Hoboken, USA : Wiley-Blackwell. - 0021-9630 .- 1469-7610. ; 56:4, s. 453-459
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Tidskriftsartikel (refereegranskat)abstract
- Background Studies have found an association between low birth weight and ADHD, but the nature of this relation is unclear. First, it is uncertain whether birth weight is associated with both of the ADHD dimensions, inattentiveness and hyperactivity-impulsivity. Second, it remains uncertain whether the association between birth weight and ADHD symptom severity is confounded by familial factors.Method: Parents of all Swedish 9- and 12-year-old twins born between 1992 and 2000 were interviewed for DSM-IV inattentive and hyperactive-impulsive ADHD symptoms by the Autism - Tics, AD/HD and other Comorbidities (A-TAC) inventory (N = 21,775 twins). Birth weight was collected prospectively through the Medical Birth Registry. We used a within-twin pair design to control for genetic and shared environmental factors.Results: Reduced birth weight was significantly associated with a mean increase in total ADHD (β = -.42; 95% CI: -.53, -.30), inattentive (β = -.26; 95% CI: -.33, -.19), and hyperactive-impulsive (β = -.16; 95% CI: -.22, -.10) symptom severity. These results imply that a change of one kilogram of birth weight corresponded to parents rating their child nearly one unit higher (going from "no" to "yes, to some extent" on a given symptom) on the total ADHD scale. These associations remained within pairs of MZ and DZ twins, and were also present when restricting the analyses to full term births.Conclusions: There is an independent association between low birth weight and all forms of ADHD symptoms, even after controlling for all environmental and genetic confounds shared within twin pairs. These results indicate that fetal growth restriction (as reflected in birth weight differences within twin pairs) and/or the environmental factors which influence it is in the casual pathway leading to ADHD.
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| 9. |
- Quinn, Patrick D., et al.
(författare)
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Childhood attention-deficit/hyperactivity disorder symptoms and the development of adolescent alcohol problems : A prospective, population-based study of Swedish twins
- 2016
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Ingår i: American Journal of Medical Genetics Part B. - Hoboken, USA : John Wiley & Sons. - 1552-4841 .- 1552-485X. ; 171:7, s. 958-970
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Tidskriftsartikel (refereegranskat)abstract
- Children with attention-deficit/hyperactivity disorder (ADHD) are at increased risk of problematic alcohol and other substance use in adolescence. This study used data from an ongoing, prospective, population-based twin study of Swedish children and adolescents to evaluate the extent to which the association between ADHD symptoms and alcohol problems reflects a unique source of genetic or environmental risk related to ADHD versus a broader predisposition to youth externalizing behavior. We used all available data from same-sex monozygotic (MZ) and dizygotic (DZ) twins on ADHD symptoms in childhood (age 9/12; N = 15,549) and alcohol problems in late adolescence (age 18; N = 2,564). Consistent with prior longitudinal studies, the phenotypic association between hyperactive/impulsive ADHD symptoms and alcohol problems was small in magnitude, whereas the association for inattentive symptoms was even weaker. Additive genetic influences explained 99.8% of the association between hyperactive/impulsive symptoms and alcohol problems. Furthermore, we found that the genetic risk specifically associated with hyperactive/impulsive symptoms was attenuated when estimated in the context of externalizing behavior liability during childhood, of which ADHD symptoms were specific expressions. In sensitivity analyses exploring hyperactivity in mid-adolescence, we found a similar pattern of genetic associations. These results are consistent with previous findings of genetically driven overlap in the etiology of ADHD and problematic alcohol use. At least some of this co-occurrence may result from a general predisposition to externalizing behaviors in youth. © 2015 Wiley Periodicals, Inc.
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| 10. |
- Ronald, A., et al.
(författare)
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A twin study of autism symptoms in Sweden
- 2011
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Ingår i: Molecular Psychiatry. - London, United Kingdom : Nature Publishing Group. - 1359-4184 .- 1476-5578. ; 16:10, s. 1039-1047
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Tidskriftsartikel (refereegranskat)abstract
- This study aimed to identify empirically the number of factors underlying autism symptoms-social impairments, communication impairments, and restricted repetitive behaviors and interests-when assessed in a general population sample. It also investigated to what extent these autism symptoms are caused by the same or different genetic and environmental influences. Autistic symptoms were assessed in a population-based twin cohort of >12,000 (9- and 12-year-old) children by parental interviews. Confirmatory factor analyses, principal component analyses and multivariate structural equation model fitting were carried out. A multiple factor solution was suggested, with nearly all analyses pointing to a three-factor model for both boys and girls and at both ages. A common pathway twin model fit the data best, which showed that there were some underlying common genetic and environmental influences across the different autism dimensions, but also significant specific genetic effects on each symptom type. These results suggest that the autism triad consists of three partly independent dimensions when assessed in the general population, and that these different autism symptoms, to a considerable extent, have partly separate genetic influences. These findings may explain the large number of children who do not meet current criteria for autism but who show some autism symptoms. Molecular genetic research may benefit from taking a symptom-specific approach to finding genes associated with autism.
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