The Experts below are selected from a list of 38382 Experts worldwide ranked by ideXlab platform
Nancy L Pedersen - One of the best experts on this subject based on the ideXlab platform.
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THE ROLE OF RETIREMENT IN COGNITIVE AGING: RESULTS FROM THE SWEDISH ADOPTION/Twin Study OF AGING
Innovation in Aging, 2019Co-Authors: Ross Andel, Deborah Finkel, Nancy L PedersenAbstract:Abstract Retirement is a major life transition that may influence the aging process. Using a two-slope growth curve model with retirement age as the pivot point, we studied change in major cognitive domains before and after retirement. Participants were 393 members of the Swedish Adoption/Twin Study of Aging who retired after the age of 50 (mean=63 years, range 51-75 years) and who were followed for over 20 years with seven testing occasions. After controlling for age, sex, and education, we observed no change in memory pre-retirement (p=.935) and significant memory decline post-retirement (Estimate=-0.17, p=.001); decline in speed, which more than doubled after retirement (Estimate=-0.20, p=.001 before, Estimate=0.54, p<.001 after); improvement in verbal abilities before (Estimate=0.15, p=.020) and decline in verbal abilities after retirement (Estimate=-0.11, p<.001); and some decline in spatial abilities before (Estimate=-0.18, p=.059) followed by accelerated decline after retirement (Estimate=-0.33, p<.001). Retirement may be a good target for intervention.
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Prevalence, Incidence Proportion, and Heritability for Tinnitus : A Longitudinal Twin Study
Ear and Hearing, 2017Co-Authors: Renata Bogo, Nancy L Pedersen, Ahmed Farah, Kjell K. Karlsson, Magnus Svartengren, Åsa SkjönsbergAbstract:OBJECTIVES: The purpose of this longitudinal Twin Study was to explore the effect of tinnitus on hearing thresholds and threshold shifts over two decades and to investigate the genetic contribution ...
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the genetic influence on diverticular disease a Twin Study
Alimentary Pharmacology & Therapeutics, 2012Co-Authors: J Granlund, Nancy L Pedersen, Patrik K E Magnusson, Tobias Svensson, Ola Olen, Fredrik Hjern, Thelin P SchmidtAbstract:BACKGROUND: The contribution of hereditary factors to the development of diverticular disease (DD) of the colon is unknown. Prevalence and location of diverticula differ in Western world compared to in Asia and several case reports describing families with DD have been published. AIM: To assess the heritability of DD in a large population-based sample of Twins. METHODS: The Swedish Twin Registry was cross-linked to the Swedish Inpatient Registry. All Twins, born between 1886 and 1980 and not dead before 1969, with a discharge diagnosis of DD were identified. Twins with diagnoses of colon cancer, coeliac disease or non-infectious colitis were excluded to decrease bias. Co-Twin odds ratio (OR), concordance rates and tetrachoric correlations were calculated for monozygotic (MZ) and same gender-dizygotic (SS-DZ) Twins. Mx-analyses were used to estimate the relative contributions of genetic effects and environmental factors to susceptibility for DD. Calculations were based on both primary and secondary discharge diagnoses to provide estimates reflecting impact of severity of the disease. RESULTS: A total of 104,452 Twins met the inclusion criteria. Of these, 2296 had a diagnosis of DD. The OR of developing the disease given one's co-Twin was affected was 7.15 (95% CI: 4.82-10.61) for MZ and 3.20 (95% CI: 2.21-4.63) for SS-DZ Twins. Similarly, concordance rates and tetrachoric correlations were higher in MZ than those in SS-DZ Twins. The heritability was estimated to 40% and the non shared environmental effects to 60%. CONCLUSION: Genetic susceptibility is an important component, along with individual specific environmental factors, for the development of diverticular disease of the colon.
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Genetic influences on suicide and nonfatal suicidal behavior: Twin Study findings
European Psychiatry, 2010Co-Authors: Nancy L Pedersen, Amy FiskeAbstract:It has been well established that suicidal behavior is familial. Twin studies provide a unique opportunity to distinguish genetic effects from other familial influences. Consistent with findings from previous Twin studies, including case series and selected samples, data from the population-based Swedish Twin Registry clearly demonstrate the importance of genetic influences on suicide. Twin studies of suicidal ideation and suicide attempts also implicate genetic influences, even when accounting for the effects of psychopathology. Future work is needed to evaluate the possibility of age and gender differences in heritability of suicide and nonfatal suicidal behavior.
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Seasonal Genetic Influence on Serum 25-Hydroxyvitamin D Levels: A Twin Study
PLOS ONE, 2009Co-Authors: Greta Snellman, Rolf Gedeborg, Sylvia Olofsson, Alicja Wolk, Hakan Melhus, Nancy L Pedersen, Karl MichaelssonAbstract:Background: Although environmental factors, mainly nutrition and UV-B radiation, have been considered major determinants of vitamin D status, they have only explained a modest proportion of the variation in serum 25hydroxyvitamin D. We aimed to Study the seasonal impact of genetic factors on serum 25-hydroxyvitamin D concentrations. Methodology/Principal findings: 204 same-sex Twins, aged 39–85 years and living at northern latitude 60u, were recruited from the Swedish Twin Registry. Serum 25-hydroxyvitamin D was analysed by high-pressure liquid chromatography and mass spectrometry. Genetic modelling techniques estimated the relative contributions of genetic, shared and individualspecific environmental factors to the variation in serum vitamin D. The average serum 25-hydroxyvitamin D concentration was 84.8 nmol/l (95% CI 81.0–88.6) but the seasonal variation was substantial, with 24.2 nmol/l (95% CI 16.3–32.2) lower values during the winter as compared to the summer season. Half of the variability in 25-hydroxyvitamin D during the summer season was attributed to genetic factors. In contrast, the winter season variation was largely attributable to shared environmental influences (72%; 95% CI 48–86%), i.e., solar altitude. Individual-specific environmental influences were found to explain one fourth of the variation in serum 25-hydroxyvitamin D independent of season. Conclusions/Significance: There exists a moderate genetic impact on serum vitamin D status during the summer season, probably through the skin synthesis of vitamin D. Further studies are warranted to identify the genes impacting on vitamin D status.
Kenneth Kendler - One of the best experts on this subject based on the ideXlab platform.
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psychiatric resilience longitudinal Twin Study
British Journal of Psychiatry, 2014Co-Authors: Ananda B Amstadter, John Myers, Kenneth KendlerAbstract:Background The source of variability in people’s response to stressful life events is poorly understood. Aims We examine the genetic and environmental underpinning of resilience (i.e. the difference between the Twins’ internalising symptoms and their predicted symptoms based on cumulative stressful life events). Method Stressful life event exposure and internalising symptoms were assessed at two time points in 7500 adult Twins. Using the residual between actual and predicted internalising symptom total score, Twin modelling was conducted for each wave separately and longitudinally. Results Resilience was found to have a moderate genetic heritability at each wave (∼31%). Qualitative gender effects were found. Incorporating error of measurement into the model increased the estimated heritability for the latent construct of resilience (∼50%). When measurement error and occasion-specific effects were removed, environmental influences contributed roughly equally to level of resilience. Conclusions Both genes and environment influence level of psychiatric resilience, and are largely stable over time. Environmental influences can have an enduring effect on resilience.
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A Twin Study of Intracerebral Volumetric Relationships
Behavior Genetics, 2010Co-Authors: J. Eric Schmitt, Kenneth Kendler, Michael C Neale, Gregory L. Wallace, Rhoshel K. Lenroot, Sarah E. Ordaz, Dede Greenstein, Liv Clasen, Jay N. GieddAbstract:Using high resolution magnetic resonance imaging data, we examined the interrelationships between eight cerebral lobar volumetric measures via both exploratory and confirmatory factor analyses in a large sample ( N = 484) of pediatric Twins and singletons. These analyses suggest the presence of strong genetic correlations between cerebral structures, particularly between regions of like tissue type or in spatial proximity. Structural modeling estimated that most of the variance in all structures is associated with highly correlated lobar latent factors, with differences in genetic covariance and heritability driven by a common genetic factor that influenced gray and white matter differently. Reanalysis including total brain volume as a covariate dramatically reduced the total residual variance and disproportionately influenced the additive genetic variance in all regions of interest.
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A Twin Study of specific bulimia nervosa symptoms
Psychological Medicine, 2009Co-Authors: Suzanne E. Mazzeo, Kenneth Kendler, Cynthia M. Bulik, Karen S. Mitchell, Steven H. Aggen, M C NealeAbstract:Background Twin studies have suggested that additive genetic factors significantly contribute to liability to bulimia nervosa (BN). However, the diagnostic criteria for BN remain controversial. In this Study, an item-factor model was used to examine the BN diagnostic criteria and the genetic and environmental contributions to BN in a population-based Twin sample. The validity of the equal environment assumption (EEA) for BN was also tested.
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personality and major depression a swedish longitudinal population based Twin Study
Archives of General Psychiatry, 2006Co-Authors: Kenneth Kendler, Charles O Gardner, Margaret Gatz, Nancy L PedersenAbstract:Context Prior studies suggest that the personality traits of neuroticism and extroversion may be related to the liability to major depression (MD). Objective To clarify the magnitude and nature of the association between neuroticism and extroversion and the risk for MD. Design Longitudinal population-based Twin cohort. Setting General community. Participants A total of 20 692 members of same-sex Twin pairs from the population-based Swedish Twin Registry who completed a self-report questionnaire assessing neuroticism and extroversion in 1972 and 1973 and were personally interviewed for lifetime history of MD more than 25 years later. Main Outcome Measure Lifetime history of modifiedDSM-IVMD. Results Levels of neuroticism strongly predicted the risks for both lifetime and new-onset MD. Twin modeling indicated that the association between neuroticism and MD resulted largely from shared genetic risk factors, with a genetic correlation of +0.46 to +0.47. Levels of extroversion were weakly and inversely related to the risks for lifetime and new-onset MD. This effect disappeared when we controlled for the level of neuroticism. Twin modeling produced similar results. Conclusions Results from both longitudinal and genetic analyses support the hypothesis that neuroticism strongly reflects the liability to MD. This association arises largely because neuroticism indexes the genetic risk for depressive illness. However, substantial proportions of the genetic vulnerability to MD are not reflected in neuroticism. By contrast, extroversion is only weakly related to risk for MD.
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A Swedish national Twin Study of lifetime major depression
American Journal of Psychiatry, 2006Co-Authors: Kenneth Kendler, Charles O Gardner, Margaret Gatz, Nancy L PedersenAbstract:Objective: Substantial evidence sup-ports the heritability of lifetime major de-pression. Less clear is whether genetic in-fluences in major depression are more important in women than in men and whether genetic risk factors are the same in the two sexes. It is not known whether genetic effects on major depression are constant across historical cohorts. Method: Lifetime major depression was assessed at personal interview by modified DSM-IV criteria in 42,161 Twins, including 15,493 complete pairs, from the national Swedish Twin Registry. Twin models were evaluated by using the program Mx. Results: Model fitting indicated that the heritability of liability to major depression was significantly higher in women (42%) than men (29%) and the genetic risk fac-tors for major depression were moderately correlated in men and women. No signifi-cant differences were seen in the etiologic roles of genetic and environmental factors in major depression in three cohorts span-ning birth years 1900–1958. Conclusions: In the largest sample to date, lifetime major depression was mod-erately heritable, with estimates similar to those in prior studies. In accord with some but not other previous investiga-tions, this Study suggests both that the heri-tability of major depression is higher in women than in men and that some ge-netic risk factors for major depression are sex-specific in their effect. No evidence was found for differences in the roles of genetic and environmental risk factors in major depression in birth cohorts span-ning nearly six decades.
Lindon J Eaves - One of the best experts on this subject based on the ideXlab platform.
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genetic and environmental influences on smoking behavior across adolescence and young adulthood in the virginia Twin Study of adolescent behavioral development and the transitions to substance abuse follow up
Twin Research and Human Genetics, 2015Co-Authors: Elizabeth K Do, Lindon J Eaves, Judy L Silberg, Elizabeth Promwormley, Donna R Miles, Hermine H MaesAbstract:Little is known regarding the underlying relationship between smoking initiation and current quantity smoked during adolescence into young adulthood. It is possible that the influences of genetic and environmental factors on this relationship vary across sex and age. To investigate this further, the current Study applied a common causal contingency model to data from a Virginia-based Twin Study to determine: (1) if the same genetic and environmental factors are contributing to smoking initiation and current quantity smoked; (2) whether the magnitude of genetic and environmental factor contributions are the same across adolescence and young adulthood; and (3) if qualitative and quantitative differences in the sources of variance between males and females exist. Study results found no qualitative or quantitative sex differences in the relationship between smoking initiation and current quantity smoked, though relative contributions of genetic and environmental factors changed across adolescence and young adulthood. More specifically, smoking initiation and current quantity smoked remain separate constructs until young adulthood, when liabilities are correlated. Smoking initiation is explained by genetic, shared, and unique environmental factors in early adolescence and by genetic and unique environmental factors in young adulthood; while current quantity smoked is explained by shared environmental and unique environmental factors until young adulthood, when genetic and unique environmental factors play a larger role.
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genetics and developmental psychopathology 2 the main effects of genes and environment on behavioral problems in the virginia Twin Study of adolescent behavioral development
Journal of Child Psychology and Psychiatry, 1997Co-Authors: Lindon J Eaves, Andrew C Heath, Emily Simonoff, Andrew Pickles, Joanne M Meyer, Judy L Silberg, Hermine H Maes, Michael Rutter, Chandra A Reynolds, Kimberly R TruettAbstract:: Little is known about the contribution of genetic and environmental factors to risk for juvenile psychopathology. The Virginia Twin Study of Adolescent Behavioral Development allows these contributions to be estimated. A population-based, unselected sample of 1412 Caucasian Twin pairs aged 8-16 years was ascertained through Virginia schools. Assessment of the children involved semi-structured face-to-face interviews with both Twins and both parents using the Child and Adolescent Psychiatric Assessment (CAPA). Self-report questionnaires were also completed by parents, children, and teachers. Measures assessed DSM-III-R symptoms of Attention Deficit Hyperactivity Disorder (ADHD). Conduct Disorder, Oppositional Defiant Disorder, Overanxious Disorder, Separation Anxiety, and Depressive Disorder. Factorially derived questionnaire scales were also extracted. Scores were normalized and standardized by age and sex. Maximum likelihood methods were used to estimate contributions of additive and nonadditive genetic effects, the shared and unique environment, and sibling imitation or contrast effects. Estimates were tested for heterogeneity over sexes. Generally, monozygotic (MZ) Twins correlated more highly than dizygotic (DZ) Twins, parental ratings more than child ratings, and questionnaire scales more highly than interviews. DZ correlations were very low for measures of ADHD and DZ variances were greater than MZ variances for these variables. Correlations sometimes differed between sexes but those for boy-girl pairs were usually similar to those for like-sex pairs. Most of the measures showed small to moderate additive genetic effects and moderate to large effects of the unique individual environment. Measures of ADHD and related constructs showed marked sibling contrast effects. Some measures of oppositional behavior and conduct disorder showed shared environmental effects. There were marked sex differences in the genetic contribution to separation anxiety, otherwise similar genetic effects appear to be expressed in boys and girls. Effects of rater biases on the genetic analysis are considered. The Study supports a widespread influence of genetic factors on risk to adolescent psychopathology and suggests that the contribution of different types of social influence may vary consistently across domains of measurement.
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the virginia Twin Study of adolescent behavioral development influences of age sex and impairment on rates of disorder
Archives of General Psychiatry, 1997Co-Authors: Emily Simonoff, John K Hewitt, Andrew Pickles, Joanne M Meyer, Judy L Silberg, Hermine H Maes, Rolf Loeber, Michael Rutter, Lindon J EavesAbstract:Background: The Virginia Twin Study of Adolescent Behavioral Development is a cohort-longitudinal epidemiological Study that uses the genetic Twin design to Study the development and maintenance of child psychiatric disorders. We determined the rates of DSM-III-R disorders, disorders with impairment, and age, sex, and co-morbidity effects. Methods: Families of 2762 white Twins aged 8 to 16 years participated. Twins and their parents were asked systematically about risk factors and current psychiatric symptoms by means of investigator-based psychiatric interviews and questionnaires. The DSM-III-R diagnoses were made for major depressive disorder, separation anxiety, overanxious disorder, simple phobia, social phobia, agoraphobia, oppositional defiant disorder, conduct disorder, and attention deficit hyperactivity disorder. Results: The 3-month point prevalence for any DSM-III-R disorders was 413 per 1000, and that for disorders with associated impairment was 142 per 1000. Emotionnal disorders with impairment occurred in 89 per 1000, with girls being more commonly affected; behavioral disorders had a prevalence of 71 per 1000, with boys being more frequently affected. The proportion with disorder who also had functional impairment varied across disorders; anxiety and phobic disorders were particularly likely not to be accompanied by impairment. Rates of emotional and behavioral disorders increased over the age range. There was extensive comorbidity among disorders. Conclusions: The prevalence rates and patterns of findings from this Study of Twins are consistent with those of other epidemiological studies, supporting previous findings of few differences in rates of psychiatric disorder between Twins and singletons. The importance of including measures of functional impairment is evident by its effect on rates of disorder and patterns of comorbidity.
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the power of the classical Twin Study to resolve variation in threshold traits
Behavior Genetics, 1994Co-Authors: Michael C Neale, Lindon J Eaves, Kenneth KendlerAbstract:We explore the power of the Twin Study to resolve sources of familial resemblance when the data are measured at the binary or ordinal level. Four components of variance were examined: additive genetic, nonadditive genetic, and common and specific environment. Curves are presented to compare the power of the continuous case with those of threshold models corresponding to different prevalences in the population: 1, 5, 10, 25, and 50%. Approximately three times the sample size is needed for equivalent power to the continuous case when the threshold is at the optimal 50%, and this ratio increases to about 10 times when 10% are above threshold. Some power may be recovered by subdividing those above threshold to form three or more ordered classes, but power is determined largely by the lowest threshold. Non-random ascertainment of Twins (i) through affected Twins and examining their coTwins or (ii) through ascertainment of all pairs in which at least one Twin is affected increases power. In most cases, strategy i is more efficient than strategy ii. Though powerful for the rarer disorders, these methods suffer the disadvantage that they rely on prior knowledge of the population prevalence. Furthermore, sampling from hospital cases may introduce biases, reducing their value. A useful approach may be to assess the population with a screening instrument; the power calculations indicate that sampling all concordant and half of the discordant pairs would be efficient, as along as the cost of screening is not too high.
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a longitudinal Twin Study of personality and major depression in women
Archives of General Psychiatry, 1993Co-Authors: Kenneth Kendler, Michael C Neale, Andrew C Heath, Ronald C Kessler, Lindon J EavesAbstract:Objective: To elucidate the nature of the etiologic relationship between personality and major depression in women. Design: A longitudinal Twin design in which Twins completed a time 1 questionnaire and, 15 months later, were personally interviewed for the occurrence of major depression during the last year and completed a time 2 questionnaire. Both questionnaires contained short forms assessing neuroticism and extraversion. Participants: 1733 Twins from female-female pairs ascertained from the population-based Virginia Twin Registry. Results: Extraversion was unrelated to lifetime or 1-year prevalence of major depression. Neuroticism was strongly related to lifetime prevalence of major depression and robustly predicted the prospective 1-year prevalence of major depression in those who, at time 1, denied previous depressive episodes. However, controlling for levels of neuroticism at time 1, levels of neuroticism at time 2 were moderately elevated in those who had had an episode of major depression between times 1 and 2 ("scar" effect) and substantially elevated in those experiencing an episode of major depression at time 2 ("state" effect). In those who developed major depression, levels of neuroticism did not predict time to onset. In the best-fit longitudinal Twin model, the proportion of the observed correlation between neuroticism and the liability to major depression that is due to shared genetic risk factors was estimated at around 70%, that due to shared environmental risk factors at around 20%, and that due to a direct causal effect of major depression on neuroticism (via both "scar" and "state" effects) at around 10%. Approximately 55% of the genetic liability of major depression appeared to be shared with neuroticism, while 45% was unique to major depression. Conclusion: In women, the relationship between neuroticism and the liability to major depression is substantial and largely the result of genetic factors that predispose to both neuroticism and major depression.
Tim D Spector - One of the best experts on this subject based on the ideXlab platform.
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cohort profile Twinsuk and healthy ageing Twin Study
International Journal of Epidemiology, 2013Co-Authors: Alireza Moayyeri, Christopher J Hammond, Ana M Valdes, Tim D SpectorAbstract:The UK's largest registry of adult Twins, or TwinsUK Registry, started in 1992 and encompasses about 12000 volunteer Twins from all over the United Kingdom. More than 70% of the registered Twins have filled at least one detailed health questionnaire and about half of them undergone a baseline comprehensive assessment and two follow-up clinical evaluations. The most recent follow-up visit, known as Healthy Ageing Twin Study (HATS), involved 3125 female Twins aged >40 years with at least one previous clinical assessment to enable inspection of longitudinal changes in ageing traits and their genetic and environmental components. The Study benefits from several state-of-the-art OMICs studies including genome-wide association, next-generation genome and transcriptome sequencing, and epigenetic and metabolomic profiles. This makes our cohort as one of the most deeply phenotyped and genotyped in the world. Several collaborative projects in the field of epidemiology of complex disorders are ongoing in our cohort and interested researchers are encouraged to get in contact for future collaborations.
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genetic influences in gastro oesophageal reflux disease a Twin Study
Journal of Medical Genetics, 2003Co-Authors: I Mohammed, Tim D Spector, Lynn Cherkas, Stuart A Riley, Nigel TrudgillAbstract:Background: A number of families have been described which include multiple members with symptomatic, endoscopic, or complicated gastro-oesophageal reflux disease (GORD). First degree relatives of patients with GORD are more likely to suffer with GORD symptoms. These observations raise the possibility of a genetic contribution to the …
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genetic influences in gastro oesophageal reflux disease a Twin Study
Gut, 2003Co-Authors: I Mohammed, Tim D Spector, Lynn Cherkas, Stuart A Riley, Nigel TrudgillAbstract:Background: A number of families have been described which include multiple members with symptomatic, endoscopic, or complicated gastro-oesophageal reflux disease (GORD). First degree relatives of patients with GORD are more likely to suffer with GORD symptoms. These observations raise the possibility of a genetic contribution to the aetiology of GORD. Aims: To determine the relative contribution of genetic factors to GORD by evaluating GORD symptoms in monozygotic (MZ) and dizygotic (DZ) Twins. Methods: A total of 4480 unselected Twin pairs, identified from a national volunteer Twin register, were asked to complete a validated symptom questionnaire. GORD was defined as symptoms of heartburn or acid regurgitation at least weekly during the past year. Results: Replies were obtained from 5032 subjects (56% response rate). A total of 1960 Twin pairs were evaluable: 928 MZ pairs (86 male pairs, mean (SD) age 52 (13) (range 19–81) years) and 1032 DZ pairs (71 male pairs, mean age 52 (13) (20–82) years). The prevalence of GORD among both groups of Twins was 18%. Casewise concordance rates were significantly higher for MZ than DZ Twins (42% v 26%; p Conclusions: There is a substantial genetic contribution to the aetiology of GORD.
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genetic influence on early age related maculopathy a Twin Study
Ophthalmology, 2002Co-Authors: Christopher J Hammond, Harold Snieder, Andrew R Webster, Alan C Bird, Clare Gilbert, Tim D SpectorAbstract:OBJECTIVE: Age-related macular degeneration (AMD) is the most common cause of blindness in industrialized countries. There has been considerable interest in the genetics of early age-related maculopathy (ARM) and AMD, because they have phenotypes similar to inherited diseases where mutations have been identified, but the heritability of ARM and AMD is unknown. DESIGN: A classical Twin Study was performed to compare the concordance in monozygotic (MZ) and dizygotic (DZ) Twins in an unselected sample of female volunteer Twins. PARTICIPANTS: Five hundred six Twin pairs, 226 MZ and 280 DZ, with a mean age of 62 years, were examined. METHODS: ARM was graded from stereoscopic macular photographs of 501 of the Twin pairs (99%) according to the International ARM Epidemiologic Study Group grading system. The casewise concordance was calculated for Twin pairs from 2 x 2 contingency tables of affected/unaffected Twins, and these tables were used in maximum likelihood genetic modeling to estimate the heritabilities of phenotypes graded. MAIN OUTCOME MEASURES: Prevalence of ARM; concordance in MZ and DZ Twins of the phenotypes of ARM, soft drusen >63 microm and > or =125 microm diameter, pigmentary changes and hard drusen ( or =20 in number); heritability of ARM and subphenotypes. RESULTS: The overall prevalence of ARM was 14.6% (95% confidence interval [CI], 12.4%-16.8%). The concordance for ARM in MZ Twins was 0.37 compared with 0.19 in DZ Twins, suggesting a role for genes. Modeling confirmed a genetic effect for phenotypes of ARM, soft drusen, pigmentary changes, and > or =20 hard drusen, although there was little genetic effect for scattered ( or =125 microm (57%) and > or =20 hard drusen (81%), with the latter being dominantly inherited. CONCLUSIONS: This Study confirms a significant genetic influence in ARM and suggests that future genetic studies should examine phenotypes of large (> or =125 microm) soft drusen and > or =20 hard drusen, because these seem to be the most heritable components.
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the genetics of haemostasis a Twin Study
The Lancet, 2001Co-Authors: Marlies De Lange, Harold Snieder, Robert A S Ariens, Tim D Spector, Peter J GrantAbstract:Summary Background The concentrations of fibrinogen, factor VII and VIII, von Willebrand factor, plasminogen activator inhibitor-1 (PAI-1), and tissue plasminogen activator have been associated with coronary-heart disease. In addition, polymorphisms in the genes coding for fibrinogen, factor VII, PA-1, and factor XIII have been reported to affect both protein concentrations and cardiovascular disease risk. Methods We did a classic Twin Study to assess heritabilities of these haemostatic factors. We enrolled 1002 female Twins; 149 pairs of monozygotic and 352 pairs of dizygotic Twins. 89 monozygotic and 196 dizygotic Twin pairs were analysed for factor VII. Findings Quantitative genetic model fitting showed that genetic factors contributed to about 41–75% of the variation in concentrations of fibrinogen, factor VII, factor VIII, PAI-1, tissue plasminogen activator, factor XIII A-subunit and B-subunit, and von Willebrand factor. Factor XIII activity showed higher (82%) and factor XIIa lower (38%) heritability. Interpretation We have shown that genetic factors have a major effect on plasma concentrations of haemostatic proteins. Our results stress the importance of research into the genetic regulation of proteins involved in haemostasis and atherothrombotic disorders, including myocardial infarction and stroke.
Jaakko Kaprio - One of the best experts on this subject based on the ideXlab platform.
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the nordic Twin Study on cancer norTwincan
Twin Research and Human Genetics, 2019Co-Authors: Jennifer R Harris, Lorelei A Mucci, Hansolov Adami, Jacob V B Hjelmborg, Kamila Czene, Jaakko KaprioAbstract:Nordic Twin studies have played a critical role in understanding cancer etiology and elucidating the nature of familial effects on site-specific cancers. The NorTwinCan consortium is a collaborative effort that capitalizes on unique research advantages made possible through the Nordic system of registries. It was constructed by linking the population-based Twin registries of Denmark, Finland, Norway and Sweden to their country-specific national cancer and cause-of-death registries. These linkages enable the Twins to be followed many decades for cancer incidence and mortality. To date, two major linkages have been conducted: NorTwinCan I in 2011–2012 and NorTwinCan II in 2018. Overall, there are 315,413 eligible Twins, 57,236 incident cancer cases and 58 years of follow-up, on average. In the initial phases of our work, NorTwinCan established the world’s most comprehensive Twin database for Studying cancer, developed novel analytical approaches tailored to address specific research considerations within the context of the Nordic data and leveraged these models and data in research publications that provide the most accurate estimates of heritability and familial risk of cancers reported in the literature to date. Our findings indicate an excess familial risk for nearly all cancers and demonstrate that the incidence of cancer among Twins mirrors the rate in the general population. They also revealed that Twin concordance for cancer most often manifests across, rather than within, cancer sites, and we are currently focusing on the analysis of these cross-cancer associations.
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gene environment contributions to energy and macronutrient intakes in 9 year old children results from the quebec newborn Twin Study
Physiology & Behavior, 2013Co-Authors: Lise Dubois, Jaakko Kaprio, Maikol Diasparra, Brigitte Bedard, Benedicte Fontainebisson, Daniel Perusse, Richard E Tremblay, Michel BoivinAbstract:Abstract Background Few Twin studies have examined nutrition-related phenotypes among children, and none has investigated energy and macronutrient intakes. Objective The objective was to quantify genetic and environmental influences on variations in energy and macronutrient intakes among children aged 9 years. Design We conducted a nutrition Study among children participating in the Quebec Newborn Twin Study, a population-based birth cohort of Twins. We derived dietary data from two multiple-pass 24-hour dietary recalls with a parent and his or her child. The analysis employed a classic Twin Study design and used data from 379 Twin pairs. Results Univariate analyses indicate that heritability for mean daily energy (kcal) and macronutrient (g) intakes was moderate, ranging from 0.34 (95% CI: 0.22, 0.46) to 0.42 (0.31, 0.53). Genetic effects also accounted for 0.28 (0.16, 0.40) of the variance in percent of energy from lipids, while only environmental (shared and unique) effects accounted for the variance in percent of energy from proteins and carbohydrates. The shared environment did not contribute to variations in daily intakes for most of the nutritional variables under Study. Multivariate analyses suggest the presence of macronutrient-specific genetic influences for lipids and carbohydrates, estimated at 0.12 (0.04, 0.19) and 0.20 (0.11, 0.29) respectively. Conclusions The unique environment (i.e., not shared by family members) has the largest influence on variances in daily energy and macronutrient intakes in 9-year-old children. This finding underscores the need to take obesogenic environments into account when planning dietary interventions for younger populations.
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does dieting make you fat a Twin Study
International Journal of Obesity, 2012Co-Authors: Jaakko Kaprio, Kirsi H Pietilainen, Suoma E Saarni, Aila RissanenAbstract:To investigate whether the paradoxical weight gain associated with dieting is better related to genetic propensity to weight gain than to the weight loss episodes themselves. Subjects included 4129 individual Twins from the population-based FinnTwin16 Study (90% of Twins born in Finland 1975–1979). Weight and height were obtained from longitudinal surveys at 16, 17, 18 and 25 years, and number of lifetime intentional weight loss (IWL) episodes of more than 5 kg at 25 years. IWLs predicted accelerated weight gain and risk of overweight. The odds of becoming overweight (body mass index (BMI)⩾25 kg m−2) by 25 years were significantly greater in subjects with one (OR 1.8, 95% CI 1.3–2.6, and OR 2.7, 1.7–4.3 in males and females, respectively), or two or more (OR 2.0, 1.3–3.3, and OR 5.2, 3.2–8.6, in males and females, respectively), IWLs compared with subjects with no IWL. In MZ pairs discordant for IWL, co-Twins with at least one IWL were 0.4 kg m−2 (P=0.041) heavier at 25 years than their non-dieting co-Twins (no differences in baseline BMIs). In DZ pairs, co-Twins with IWLs gained progressively more weight than non-dieting co-Twins (BMI difference 1.7 kg m−2 at 16 years and 2.2 kg m−2 at 25 years, P<0.001). Our results suggest that frequent IWLs reflect susceptibility to weight gain, rendering dieters prone to future weight gain. The results from the MZ pairs discordant for IWLs suggest that dieting itself may induce a small subsequent weight gain, independent of genetic factors.
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associations between long term physical activity waist circumference and weight gain a 30 year longitudinal Twin Study
International Journal of Obesity, 2008Co-Authors: Katja Waller, Jaakko Kaprio, Urho M KujalaAbstract:Physical activity level and obesity are both partly determined by genes and childhood environment. To determine the associations between long-term leisure-time physical activity, weight gain and waist circumference and whether these are independent of genes and childhood effects. The Study design is a 30-year follow-up Twin Study in Finland. For this Study, 146 Twin pairs were comprehensively identified from the large Finnish Twin Cohort. These Twin pairs were discordant for both intensity and volume of leisure physical activity in 1975 and 1981 and were healthy in 1981. At follow-up in 2005, both members of 89 pairs were alive and participated in a structured telephone interview. In the interview self-measured weight and waist circumference, and physical activity level for the whole follow-up were assessed. Paired tests were used in the statistical analyses. Waist circumference at 30-year follow-up (2005) and change in weight from 1975 to 2005. In the 42 Twin pairs discordant for physical activity at all time points during the 30-year period, the mean weight gain from 1975 through 2005 was 5.4 kg (95% confidence interval (CI) 2.0–8.9) less in the active compared to inactive co-Twins (paired t-test, P=0.003). In 2005, the mean waist circumference was 8.4 cm (95% CI 4.0–12.7) less in the active compared with inactive co-Twins (P<0.001). These trends were similar for both monozygotic and dizygotic Twin pairs. Pairwise differences in weight gain and waist circumference were not seen in the 47 Twin pairs, who were not consistently discordant for physical activity. Persistent participation in leisure-time physical activity is associated with decreased rate of weight gain and with a smaller waist circumference to a clinically significant extent even after partially controlling for genetic liability and childhood environment.
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prevalence and genetics of sleepwalking a population based Twin Study
Neurology, 1997Co-Authors: Christer Hublin, Jaakko Kaprio, Kauko Heikkila, Markku Partinen, Markku KoskenvuoAbstract:We investigated the prevalence of sleepwalking using a well defined population previously used for epidemiologic investigations:the Finnish Twin Cohort. The Study population consisted of 11,220 subjects aged 33 to 60 years, and it included 1,045 monozygotic and 1,899 dizygotic Twin pairs. Questions on the frequency of sleepwalking were asked separately for occurrence in childhood and adulthood. Childhood sleepwalking was significantly more frequent in women ("often" in 2.8% of women and 2.0% of men and "sometimes" in 6.9% of women and 5.7% of men). As adults, sleepwalking had occurred in 3.9% of men and in 3.1% of women, and it was reported "weekly" in 0.4% for both genders. There was no significant difference in frequency between monozygotic and dizygotic Twin individuals, either in childhood or adulthood. For sleepwalking in childhood the probandwise concordance rate was 0.55 for monozygotic and 0.35 for dizygotic pairs, and for adults, 0.32 for monozygotic, and 0.06 for dizygotic pairs. Those who reported never having walked in their sleep in childhood did so as adults rarely (0.6%), both men and women. Those who reported walking in their sleep often or sometimes in childhood did so as adults for 24.6% of men and for 18.3% of women. Of adult men sleepwalkers 88.9% had a positive history of sleepwalking in childhood, and in women, 84.5%. The proportion of total phenotypic variance attributed to genetic influences was 66% in men and 57% in women in childhood sleepwalking, and 80% in men and 36% in women in adult sleepwalking. Our results show that there are substantial genetic effects in sleepwalking in both childhood and adulthood. NEUROLOGY 1997;48: 177-181
