Search results for "Twin study"
showing 10 items of 115 documents
DSM-IV Combined Type ADHD Shows Familial Association With Sibling Trait Scores
2008
Contains fulltext : 69060.pdf (Publisher’s version ) (Closed access) Attention deficit hyperactivity disorder (ADHD) is a discrete clinical syndrome characterized by the triad of inattention, hyperactivity, and impulsivity in the context of marked impairments. Molecular genetic studies have been successful in identifying genetic variants associated with ADHD, particularly with DSM-IV inattentive and combined subtypes. Quantitative trait locus (QTL) approaches to linkage and association mapping have yet to be widely used in ADHD research, although twin studies investigating individual differences suggest that genetic liability for ADHD is continuously distributed throughout the population, u…
Early maturation and substance use across adolescence and young adulthood: A longitudinal study of Finnish twins.
2017
AbstractEarly maturation, indexed by pubertal development (PD), has been associated with earlier initiation and greater frequency of adolescent substance use, but this relationship may be biased by confounding factors and effects that change across development. Using a population-based Finnish twin sample (N = 3,632 individuals), we conducted twin modeling and multilevel structural equation modeling of the relationship between PD and substance use at ages 12–22. Shared environmental factors contributed to early PD and heavier substance use for females. Biological father absence was associated with early PD for boys but not girls, and did not account for the relationship between PD and subst…
Shared genetic risk between eating disorder- and substance-use-related phenotypes: Evidence from genome-wide association studies
2020
AbstractEating disorders and substance use disorders frequently co-occur. Twin studies reveal shared genetic variance between liabilities to eating disorders and substance use, with the strongest associations between symptoms of bulimia nervosa (BN) and problem alcohol use (genetic correlation [rg], twin-based=0.23-0.53). We estimated the genetic correlation between eating disorder and substance use and disorder phenotypes using data from genome-wide association studies (GWAS). Four eating disorder phenotypes (anorexia nervosa [AN], AN with binge-eating, AN without binge-eating, and a BN factor score), and eight substance-use-related phenotypes (drinks per week, alcohol use disorder [AUD], …
Genetic heterogeneity in ADHD: DAT1 gene only affects probands without CD
2008
Contains fulltext : 70183.pdf (Publisher’s version ) (Closed access) Previous studies have found heterogeneous association between DAT1-3'-UTR-VNTR and attention deficit hyperactivity disorder (ADHD). Various proportions of conduct disorder (CD) comorbidity in their ADHD samples may partially explain the observational discrepancies. Evidence for this comes from family and twin studies which found ADHD probands with CD (ADHD + CD) are genetically different from those without CD (ADHD - CD). Genotypes of 20 DAT1 markers were analyzed in 576 trios, consisting of 141 ADHD + CD and 435 ADHD - CD. In addition to the classical TDT test, a specific genetic heterogeneity test was performed to identi…
Postmenopausal hormone replacement therapy modifies skeletal muscle composition and function: a study with monozygotic twin pairs
2009
We investigated whether long-term hormone replacement therapy (HRT) is associated with mobility and lower limb muscle performance and composition in postmenopausal women. Fifteen 54- to 62-yr-old monozygotic female twin pairs discordant for HRT were recruited from the Finnish Twin Cohort. Habitual (HWS) and maximal (MWS) walking speeds over 10 m, thigh muscle composition, lower body muscle power assessed as vertical jumping height, and maximal isometric hand grip and knee extension strengths were measured. Intrapair differences (IPD%) with 95% confidence intervals (CI) were calculated. The mean duration of HRT use was 6.9 ± 4.1 yr. MWS was on average 7% (0.9 to 13.1%, P = 0.019) and muscle…
Genetics of maximal walking speed and skeletal muscle characteristics in older women.
2008
AbstractThe aim of this study was to examine whether maximal walking speed, maximal isometric muscle strength, leg extensor power and lower leg muscle cross-sectional area (CSA) shared a genetic effect in common. In addition, we wanted to identify the chromosomal areas linked to maximal walking speed and these muscle characteristics and also investigate whether maximal walking speed and these three skeletal muscle characteristics are regulated by the same chromosomal areas. We studied 217 monozygotic (MZ) and dizygotic (DZ) female twin pairs aged 66 to 75 years in the Finnish Twin Study on Aging study. The DZ pairs (94) were genotyped for 397 microsatellite markers in 22 autosomes and X-chr…
Do epigenetic clocks provide explanations for sex differences in lifespan? A cross-sectional twin study
2021
ABSTRACTBackgroundThe sex gap in life expectancy has been narrowing in Finland over the past four to five decades; however, on average, women still live longer than men. Epigenetic clocks are markers for biological aging that predict lifespan. In this study, we examined the mediating role of lifestyle factors on the association between sex and biological aging in younger and older adults.MethodsOur sample included same-sex younger and older twins (21-42-y, n = 1110; 50-76-y, n = 763) and younger opposite-sex twins (21-30-y, n = 302). Blood-based DNA methylation (DNAm) was used to compute epigenetic age acceleration by four epigenetic clocks as a measure of biological aging. Path modelling w…
Aetiology for the covariation between combined type ADHD and reading difficulties in a family study: the role of IQ
2012
Background: Twin studies using both clinical and population-based samples suggest that the frequent co-occurrence of attention deficit hyperactivity disorder (ADHD) and reading ability/disability (RD) is largely driven by shared genetic influences. While both disorders are associated with lower IQ, recent twin data suggest that the shared genetic variability between reading difficulties and ADHD inattention symptoms is largely independent from genetic influences contributing to general cognitive ability. The current study aimed to extend the previous findings that were based on rating scale measures in a population sample by examining the generalisability of the findings to a clinical popul…
Genetic and environmental influences on non-specific neck pain in early adolescence: A classical twin study
2012
Background Prevalence of neck pain has increased among adolescents. The origins of adult chronic neck pain may lie in late childhood, but for early prevention, more information is needed about its aetiology. We investigated the relative roles of genetic and environmental factors in early adolescent neck pain with a classic twin study. Methods Frequency of neck pain was assessed with a validated pain questionnaire in a population-based sample of nearly 1800 pairs of 11–12-year-old Finnish twins. Twin pair similarity for neck pain was quantified by polychoric correlations, and variance components were estimated with biometric structural equation modelling. Results Prevalence of neck pain repo…