| 1. |
- Brikell, Isabell, et al.
(författare)
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Heritability of attention-deficit hyperactivity disorder in adults
- 2015
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Ingår i: American Journal of Medical Genetics Part B. - Hoboken, USA : Wiley-Blackwell. - 1552-4841 .- 1552-485X. ; 168:6, s. 406-413
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Forskningsöversikt (refereegranskat)abstract
- Attention-deficit/hyperactivity disorder (ADHD) is a common neurodevelopmental disorder. Symptoms often persist into adulthood, with a prevalence of 2.5-5% in adult populations. Twin studies in childhood consistently report high heritabilities of 70-80%, while studies in adult samples show only moderate heritability of 30-40% when estimated from self-ratings. This review summarizes the available research on the heritability of ADHD in adults. Three key findings are outlined: (i) self-ratings lead to relatively low heritability estimates of ADHD, independent of age and whether ratings refer to current or retrospective symptoms; (ii) studies relying on different informants to rate each twin within a pair (i.e., self-ratings and different parents/teachers rating each twin in a pair) consistently yield lower heritability estimates than studies relying on ratings from a single informant; (iii) studies using cross-informant data via either combined parent and self-ratings or clinical diagnoses information suggest that the heritability of ADHD in adults could be as high as 70-80%. Together, the reviewed studies suggest that the previously reported low heritability of ADHD in adults is unlikely to reflect a true developmental change. Instead, the drop in heritability is better explained by rater effects related to a switch from using one rater for both twins in a pair (parent/teacher) in childhood, to relying on self-ratings (where each twin rates themselves) of ADHD symptoms in adulthood. When rater effects are addressed using cross-informant approaches, the heritability of ADHD in adults appears to be comparable to the heritability of ADHD in childhood.
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| 2. |
- Johansson Capusan, Andrea, et al.
(författare)
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Genetic and environmental contributions to the association between attention deficit hyperactivity disorder and alcohol dependence in adulthood : A large population-based twin study
- 2015
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Ingår i: American Journal of Medical Genetics Part B. - Hoboken, USA : Wiley-Blackwell. - 1552-4841 .- 1552-485X. ; 168:6, s. 414-422
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Tidskriftsartikel (refereegranskat)abstract
- Previous research indicates that attention deficit hyperactivity disorder (ADHD) frequently co-occurs with alcohol dependence; however, the extent to which shared genetic risk factors underpin this association remains unclear. The aim of this study is to investigate the relative importance of genetic, shared, and nonshared environmental factors for the overlap between ADHD and alcohol dependence in adults. Almost 18,000 adult twins aged 20-45 years, from more than 12,000 twin pairs (5,420 complete pairs), from the population-representative Swedish Twin Registry, were included. Self-ratings were used to assess symptoms of ADHD and alcohol dependence. Twin analysis was used to determine the role of additive genetic (A), shared (C), and nonshared environmental (E) factors. As a result, we found a significant association between ADHD and alcohol dependence (odds ratio 3.58; 95% confidence interval, 2.85-4.49). Twin analysis suggested that shared genetic risk factors explained 64% of the overlap between ADHD and alcohol dependence. Nonshared environmental factors accounted for the remaining 36%, whereas the contribution of shared environmental factors was minimal. We found no support for statistically significant sex differences in the overlap between ADHD and alcohol dependence. In conclusion the overlap between ADHD and alcohol dependence in adulthood was largely explained by shared genetic risk factors. This is an important step toward understanding the underlying nature of the risk of alcohol dependence in patients with ADHD and suggests that individuals with ADHD and their family members are important targets for alcohol prevention and treatment.
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| 3. |
- Kuja-Halkola, Ralf, et al.
(författare)
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Codevelopment of ADHD and externalizing behavior from childhood to adulthood
- 2015
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Ingår i: Journal of Child Psychology and Psychiatry. - Stockholm : Wiley-Blackwell. - 0021-9630 .- 1469-7610. ; 56:6, s. 640-647
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Attention-Deficit/Hyperactivity Disorder (ADHD) frequently co-occurs with externalizing disorders, but a clear understanding of the etiologic underpinnings is hampered by the limited understanding of the codevelopment of the traits from childhood into early adulthood.METHODS: Using a birth cohort of 2600 twins, the Swedish Twin study of Child and Adolescent Development study, assessed at ages 8-9, 13-14, 16-17, and 19-20, we investigated the codevelopment of ADHD and externalizing behavior from childhood to adulthood. The analyses examined ADHD-like and externalizing traits, as rated by twins and their parents using the Attention Problems scale and Externalizing scale of the Child Behavior Checklist, and estimated cross-lagged effects (one trait at one time-point predicting the other at the next). The covariation between the traits were decomposed into stable (effects carried over from the prior time-points) and innovative (new effects for each time-point) sources; each source was further decomposed into additive genetics, shared and nonshared environment.RESULTS: The analysis suggested that externalizing traits in middle childhood (age 8-9) predicted ADHD-like traits in early adolescence (age 13-14), whereas the reverse association was nonsignificant. In contrast, ADHD-like traits in lateadolescence (age 16-17) predicted externalizing traits in early adulthood (age 19-20). The correlation between ADHD-like and externalizing traits increased over time. At all time-points, innovative sources contributed substantially to maintained comorbidity. Genetic effects explained 67% of the covariation at each time-point; importantly, nearly 50% of these effects were innovative.CONCLUSIONS: This study challenges the belief that ADHD generally precedes externalizing behaviors; rather, change in the etiologic factors across the development is the rule. The effects were due to both new genetic and environmental factors emerging up to young adulthood. Clinicians and researchers needs to consider complex etiologic and developmental models for the comorbidity between ADHD and externalizing behaviors.
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| 4. |
- Latvala, Antti, et al.
(författare)
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A longitudinal study of resting heart rate and violent criminality in more than 700000 men
- 2015
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Ingår i: JAMA Psychiatry. - Stockholm : Karolinska Institutet, Dept of Medical Epidemiology and Biostatistics. - 2168-6238 .- 2168-622X.
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Tidskriftsartikel (refereegranskat)abstract
- IMPORTANCE: Low resting heart rate is a well-replicated physiological correlate of aggressive and antisocial behavior in children and adolescents, but whether low resting heart rate increases the risk of violence and other antisocial and risk-taking behaviors in adulthood has not been studied in representative samples. OBJECTIVE: To study the predictive association of resting heart rate with violent and nonviolent criminality and with fatal and nonfatal injuries owing to assaults and unintentional injuries in the population. DESIGN, SETTING, AND PARTICIPANTS: We conducted a study of data from several Swedish national registers on 710 264 Swedish men in the general population born from 1958 to 1991, with a follow-up of up to 35.7 years. Outcome data were available and analyzed from January 1, 1973, through December 31, 2009. Resting heart rate was measured together with blood pressure at mandatory military conscription testing at a mean (SD) age of 18.2 (0.5) years. MAIN OUTCOMES AND MEASURES: Violent and nonviolent criminal convictions and medical treatments or deaths owing to assaults and unintentional injuries. RESULTS: In models adjusted for physical, cardiovascular, psychiatric, cognitive, and socioeconomic covariates, compared with 139 511 men in the highest quintile of the distribution of resting heart rate ( 83 beats/min), 132 595 men with the lowest quintile (heart rate, 60 beats/min) had a 39% (95%CI, 35%-44%) higher hazard of being convicted of violent crimes and a 25%(95%CI, 23%-28%) higher hazard of being convicted of nonviolent crimes. The corresponding hazard was 39% higher for assault injuries (95%CI, 33%-46%) and for unintentional injuries (95%CI, 38%-41%). Further adjustment for cardiorespiratory fitness in a subset of 572 610 men with data from an exercise test did not reduce the associations. Similar associations were found between low systolic blood pressure and violent and nonviolent criminality and for assault injuries when systolic blood pressure was studied instead of resting heart rate in more than 1 million men. CONCLUSIONS AND RELEVANCE Among men, low resting heart rate in late adolescence was associated with an increased risk for violent criminality, nonviolent criminality, exposure to assault, and unintentional injury in adulthood. Most of these results were replicated with low systolic blood pressure. Resting heart rate and other autonomic measures merit further study in the development and prevention of violence and antisocial behaviour.
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| 5. |
- Latvala, Antti, et al.
(författare)
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Paternal antisocial behavior and sons' cognitive ability : a population-based quasiexperimental study
- 2015
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Ingår i: Psychological Science. - Stockholm : Karolinska Institutet, Dept of Medical Epidemiology and Biostatistics. - 0956-7976 .- 1467-9280.
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Tidskriftsartikel (refereegranskat)abstract
- Parents’ antisocial behavior is associated with developmental risks for the offspring but effects on cognitive ability are unknown. We used linked Swedish register data for a large sample of adolescent men (N = 1,177,173) and their parents to estimate associations between fathers’ criminal convictions and sons’ cognitive ability assessed at compulsory military conscription. Mechanisms behind the association were tested in children-of-siblings models across three types of sibling fathers (half-siblings, full-siblings, and monozygotic twins) with increasing genetic relatedness, and in quantitative genetic models. Fathers’ convictions associated with lower cognitive ability in sons (any crime: Cohen’s d = -.28; violent crimes: Cohen’s d = -.49). Adjusting for more genetic factors gradually reduced and eventually eliminated the association. Nuclear family environmental factors did not contribute to the association. Our results suggest that the association between paternal antisocial behavior and offspring cognitive ability is not causal but mostly due to underlying genetic factors.
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| 6. |
- Rommel, Anna-Sophie, et al.
(författare)
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Is Physical Activity Causally Associated With Symptoms of Attention-Deficit/Hyperactivity Disorder?
- 2015
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Ingår i: Journal of the American Academy of Child and Adolescent Psychiatry. - Amsterdam, Netherlands : Elsevier. - 0890-8567 .- 1527-5418. ; 54:7, s. 565-570
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Tidskriftsartikel (refereegranskat)abstract
- Objective: Emerging evidence suggests that physical activity (PA) enhances cognition and may be a protective factor for attention-deficit/hyperactivity disorder (ADHD). Yet the impact of PA on ADHD symptoms has been investigated only in a few undersized, nonrandomized, and retrospective studies. We examined the effect of PA during late adolescence on ADHD symptoms in early adulthood while controlling for unmeasured genetic and shared environmental confounding.Method: The effect of PA at age 16 to 17 years (baseline) on ADHD symptoms at age 19 to 20 years (follow-up) was examined using a within-monozygotic (MZ) twins fixed-effects model in 232 MZ twin pairs born in Sweden between May 1985 and December 1986. Parents rated their children's DSM ADHD symptoms at baseline and follow-up. Participants' weekly energy expenditure (in metabolic equivalent task minutes per week) was based on self-reports at baseline of PA frequency, intensity, and duration.Results: Greater weekly energy expenditure in adolescence was significantly associated with reduced ADHD symptom levels in early adulthood, even when controlling for unmeasured confounding (all genetic and environmental factors shared within MZ twin pairs) as well as ADHD symptoms and body mass index (BMI) at baseline, β = -0.21, p = .013 (95% CI = -0.38 to -0.05). Similar results were observed for the 2 ADHD subcomponents: hyperactivity/impulsivity, β = -0.21, p = .022 (95% CI = -0.39 to -0.03), and inattention, β = -0.19, p = .049 (95% CI = -0.36 to -0.0005).Conclusion: In line with a causal hypothesis, PA was inversely associated with ADHD symptoms, even after adjusting for unmeasured confounding. These findings suggest that PA in adolescence might decrease ADHD symptoms in early adulthood. However, given the size of the effect, the clinical value of this intervention needs to be explored further.
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| 7. |
- Saha, Rama, et al.
(författare)
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Heritability of endometriosis
- 2015
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Ingår i: Fertility and Sterility. - : Elsevier BV. - 0015-0282 .- 1556-5653. ; 104:4, s. 947-952
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: To estimate the relative contribution of genetic influences and prevalence on endometriosis.DESIGN: Analysis of self-reported data from a nationwide population-based twin registry.SETTING: Not applicable.PATIENT(S): A total of 28,370 women, female monozygotic (MZ) or dizygotic (DZ) twins, who participated in either of two surveys (1998-2002 or 2005-2006).INTERVENTION(S): None.MAIN OUTCOME MEASURE(S): Self-reported endometriosis, validated by medical records.RESULT(S): A history of endometriosis was reported by 1,228 female twins. The probandwise concordance was 0.21 for MZ and 0.10 for DZ twins. Higher within-pair (tetrachoric) correlation was observed among MZ (0.47) compared with DZ (0.20) twins. The best-fitting model revealed a contribution of 47% by additive genetic factors and the remaining 53% attributed to unique environmental effects.CONCLUSION(S): Our findings suggest both genetic and unique (nonshared) environmental influences on the complex etiology of endometriosis and support the hypothesis that genes have a strong influence on phenotypic manifestations of endometriosis.
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| 8. |
- Song, Jie, et al.
(författare)
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Bipolar disorder and its relation to major psychiatric disorders : a family-based study in the Swedish population
- 2015
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Ingår i: Bipolar Disorders. - Stockholm : Wiley-Blackwell. - 1398-5647 .- 1399-5618. ; 17:2, s. 184-193
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVES: Bipolar disorder (BPD) shares genetic components with other psychiatric disorders; however, uncertainty remains about where in the psychiatric spectra BPD falls. To understand the etiology of BPD, we studied the familial aggregation of BPD and co-aggregation between BPD and schizophrenia, depression, anxiety disorders, attention-deficit hyperactivity disorder, drug abuse, personality disorders, and autism spectrum disorders.METHODS: A population-based cohort was created by linking several Swedish national registers. A total of 54,723 individuals with BPD were identified among 8,141,033 offspring from 4,149,748 nuclear families. The relative risk of BPD in relatives and the co-occurrence of other psychiatric disorders in patients with BPD and their relatives were compared to those of matched-population controls. Structural equation modeling was used to estimate the heritability and tetrachoric correlation.RESULTS: The familial risks for relatives of BPD probands were 5.8-7.9 in first-degree relatives, and decreased with genetic distance. Co-occurrence risks for other psychiatric disorders were 9.7-22.9 in individuals with BPD and 1.7-2.8 in full siblings of BPD probands. Heritability for BPD was estimated at 58%. The correlations between BPD and other psychiatric disorders were considerable (0.37-0.62) and primarily due to genetic effects. The correlation with depression was the highest (0.62), and was 0.44 for schizophrenia.CONCLUSIONS: The high familial risks provide evidence that genetic factors play an important role in the etiology of BPD, and the shared genetic determinants suggest pleiotropic effects across different psychiatric disorders. Results also indicate that BPD is in both the mood and psychotic spectra, but possibly more closely related to mood disorders.
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