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Purpose Methods Results Conclusion To examine age‐related macular degeneration (AMD) and retinal pigment epithelium (RPE)–Bruch's membrane (BrM) complex volume associations in monozygotic twin pairs.In this study, 106 elderly twins (53 twin pairs) from the Finnish Twin Cohort study were recruited. Each participant underwent dilated 35‐degree digital colour fundus photography (CFP), and spectral domain optical coherence tomography (OCT) and replied to a structured study questionnaire. The CFPs were graded according to the Age‐Related Eye Disease Study (AREDS) classification. The OCT images were segmented and volumetric data of the RPE‐BrM complex volume was calculated with the Orion™ software. The worse eye according to AREDS classification was used for the analysis.Twenty‐nine (55%) of the twin pairs were discordant with regard to AREDS classification. Fourteen (26%) pairs were discordant with one twin participant having AMD (AREDS 2–4) and the other being unaffected (AREDS 1). Four (8%) pairs had one twin participant with intermediate or late AMD (AREDS 3–4) versus the other being unaffected (AREDS 1). The within‐pair polychoric correlation for AREDS was 0.605 (95% confidence interval 0.418–0.792).In multivariate analysis intermediate and late AMD as well as age associated with RPE‐BrM complex volume. RPE‐BrM complex volume showed a within twin pair correlation, r = 0.430 (95% confidence interval 0.172–0.688, p < 0.01).A substantial proportion of monozygotic twin pairs are discordant with regard to age‐related macular degeneration phenotype. RPE‐BrM complex volume associated with age and intermediate and late AMD. [ABSTRACT FROM AUTHOR]

The UK Biobank study on chronotype and mortality suggested small increases of all-cause and cardiovascular mortality in a 6.5-year follow-up. Our aim was to constructively replicate findings from it in a longer follow-up. A questionnaire was administered to the population-based adult Finnish Twin Cohort in 1981 (response rate 84%). The study population included 23 854 participants who replied to the question: "Try to assess to what extent you are a morning person or an evening person," with four response alternatives (anchored from "clearly a morning person" to "clearly an evening person"). Vital status and cause of death data were provided by nationwide registers up to the end of 2018. Hazard ratios for mortality were computed based on 8728 deaths. Adjustments were made for education, alcohol, smoking, BMI, and sleep duration. The covariate adjusted model showed a 9% increase of all-cause mortality for the evening-type group (HR = 1.09, 95% CI 1.01–1.18), with attenuation mainly due to smoking and alcohol. Their importance was highlighted by observing no increased mortality among non-smokers who were at most light drinkers. There was no increase in any cause-specific mortality. Our results suggest that there is little or no independent contribution of chronotype to mortality. [ABSTRACT FROM AUTHOR]

Background higher educational attainment and less midlife cardiovascular risk factors are related to better old-age cognition. Whether education moderates the association between cardiovascular risk factors and late-life cognition is not known. We studied if higher education provides resilience against the deteriorative effects of higher middle-age body mass index (BMI) and a combination of midlife cardiovascular risk factors on old-age cognition. Methods the study population is the older Finnish Twin Cohort (n  = 4,051, mean age [standard deviation, SD] = 45.5 years [6.5]). Cardiovascular risk factors and education were studied at baseline with questionnaires in 1975, 1981 and/or 1990 (participation rates of 89, 84 and 77%, respectively). Cognition was evaluated with telephone interviews (participation rate 67%, mean age [SD] =73.4 [2.9] years, mean follow-up [SD] = 27.8 [6.0] years) in 1999–2017. We studied the main and interactive effects of education and BMI/dementia risk score on late-life cognition with linear regression analysis. The study design was formulated before the pre-defined analyses. Results years of education moderated the association between BMI with old-age cognition (among less educated persons, BMI-cognition association was stronger [ B  = −0.24 points per BMI unit, 95% CI −0.31, −0.18] than among more educated persons [ B  = −0.06 points per BMI unit, 95% CI −0.16, 0.03], P interaction < 0.01). There was a similar moderating effect of education on dementia risk score consisting of cardiovascular risk factors (P  < 0.001). Conclusions our results support the cognitive reserve hypothesis. Those with higher education may tolerate the deteriorative effects of midlife cardiovascular risk factors on old-age cognition better than those with lower education. [ABSTRACT FROM AUTHOR]

- We studied cortical amyloid – episodic memory association in twin pairs - Cognitively discordant twin pairs were identified using telephone interview - 45 twin pairs participated in PET imaging and in-person neuropsychological testing - Within-twin pair differences in amyloid and memory were associated with each other - Higher amyloid is related to poorer memory even when controlling for genetic effects We studied the association between episodic memory and cortical fibrillar β-amyloid pathology within twin pairs. Using telephone-administered cognitive screening of 1415 twin pairs in a population-based older Finnish Twin Cohort study, we identified 45 (mean [SD] age 72.9 [4.0] years, 40% women) cognitively discordant same-sex twin pairs (24 dizygotic and 21 monozygotic) without neurological or psychiatric disorders other than AD or mild cognitive impairment. In-person neuropsychological testing was conducted. Cortical amyloid was measured with carbon 11-labelled Pittsburgh compound B ([11C]PiB) positron emission tomography imaging and quantified as the average standardized uptake value ratio in cortical regions affected in AD. Larger within-twin pair differences in verbal immediate (r = -0.42) and delayed free recall (r = -0.41), and visual delayed free recall (r = -0.46) were associated with larger within-twin pair differences in [11C]PiB uptake (p 's < 0.01). Correlations were not significantly different in dizygotic and monozygotic pairs suggesting that the episodic memory-cortical amyloid relationship is not confounded by genetic effects. However, larger samples are needed to draw more definitive conclusions. [ABSTRACT FROM AUTHOR]

Aims: To investigate how strongly smoking dependence and smoking dependence motives are associated with depressive symptoms among daily smokers and if these associations are independent of measured confounders and shared familial factors. Design Cross‐sectional individual‐based and within‐pair analyses. Setting: Fourth wave of the population‐based Finnish Twin Cohort conducted in 2011. Participants: 918 daily smokers born 1945–1957 (48% men), mean age 59.5 years including 38 twin pairs discordant for depression. Measurements Depressive symptoms were assessed using the Center for Epidemiologic Studies Depression scale with a cut off value ≥20 for depression. Smoking dependence was assessed using the Fagerström Test for Cigarette Dependence (FTCD) and smoking dependence motives with three subscales from the multi‐dimensional Brief Wisconsin Inventory of Smoking Dependence Motives (WISDM): primary dependence motives (PDM), affective enhancement (AE), and Taste. Logistic regressions, using standardized scores of independent variables and adjusted for multiple confounders with correction for sampling as twin pairs, were used in the individual‐based analyses. Conditional logistic regression was used to control for shared familial factors in discordant twin pairs. Findings Prevalence of depression was 18% (n = 163: 61 [14%] in men, n = 102 [22%] in women). Higher smoking dependence measured by the FTCD (OR 1.45; 95% CI 1.20, 1.75), and dependence motives measured by the PDM (1.56; 1.30, 1.87) and the AE (1.54; 1.28, 1.85) were associated with higher odds of depression. The associations remained after adjusting for individual confounders, except for neuroticism, which attenuated all associations. FTCD, PDM, and AE showed associations with depression within depression‐discordant monozygotic pairs, suggesting an association independent of familial factors. Conclusions: Depression appears to be associated with smoking dependence and smoking dependence motives related to heavy, automatic use and use to regulate affective states. The associations appear to be confounded or mediated by neuroticism but are independent of shared familial influences. [ABSTRACT FROM AUTHOR]

As the number of obese people is globally increasing, reports about the putative protective effect of obesity in life-threatening diseases, such as subarachnoid hemorrhage (SAH), are gaining more interest. This theory—the obesity paradox—is challenging to study, and the impact of obesity has remained unclear in survival of several critical illnesses, including SAH. Thus, we performed a systematic review to clarify the relation of obesity and SAH mortality. Our study protocol included systematic literature search in PubMed, Scopus, and Cochrane library databases, whereas risk-of-bias estimation and quality of each selected study were evaluated by the Critical Appraisal Skills Program and Cochrane Collaboration guidelines. A directional power analysis was performed to estimate sufficient sample size for significant results. From 176 reviewed studies, six fulfilled our eligibility criteria for qualitative analysis. One study found paradoxical effect (odds ratio, OR = 0.83 (0.74–0.92)) between morbid obesity (body mass index (BMI) > 40) and in-hospital SAH mortality, and another study found the effect between continuously increasing BMI and both short-term (OR = 0.90 (0.82–0.99)) and long-term SAH mortalities (OR = 0.92 (0.85–0.98)). However, according to our quality assessment, methodological shortcomings expose all reviewed studies to a high-risk-of-bias. Even though two studies suggest that obesity may protect SAH patients from death in the acute phase, all reviewed studies suffered from methodological shortcomings that have been typical in the research field of obesity paradox. Therefore, no definite conclusions could be drawn. [ABSTRACT FROM AUTHOR]

We aimed to investigate the associations of long‐term leisure‐time physical inactivity, body mass index (BMI) change, and education with sitting time in a 35‐year follow‐up based on self‐reports in surveys. Influences of working status in 2011 and familial confounding on the associations were tested. Data were based on the population‐based Finnish Twin Cohort of 5232 twins (53‐67‐year‐old, 41% men) with four surveys in 1975‐2011. Statistical analyses were performed using linear regression with several covariates. The effect of familial confounding (genetics and shared environment) was analyzed using a co‐twin control design which should be interpreted as if familial confounding plays a role, an association should be seen among all individuals but not in discordant twin pairs. Compared to those not at work, those at work had a longer total sitting time/d. For those at work, higher education was associated with more total sitting but with less non‐work sitting. Long‐term leisure‐time physical inactivity was associated with more non‐work sitting among those at work, whereas long‐term weight gain with more total and non‐work sitting regardless of working status. Familial confounding attenuated the associations, except for the association of increasing BMI with total and non‐work sitting among women at work. To conclude, total sitting time was longer among those still at work, but it was also influenced by long‐term leisure‐time physical inactivity, higher education, and an increase of BMI over the years. Public health efforts should be targeted to reduce sedentary behavior by promoting life‐long leisure‐time physical activity and weight control. [ABSTRACT FROM AUTHOR]

The older Finnish Twin Cohort (FTC) was established in 1974. The baseline survey was in 1975, with two follow-up health surveys in 1981 and 1990. The fourth wave of assessments was done in three parts, with a questionnaire study of twins born during 1945-1957 in 2011-2012, while older twins were interviewed and screened for dementia in two time periods, between 1999 and 2007 for twins born before 1938 and between 2013 and 2017 for twins born in 1938-1944. The content of these wave 4 assessments is described and some initial results are described. In addition, we have invited twin-pairs, based on response to the cohortwide surveys, to participate in detailed in-person studies; these are described briefly together with key results. We also review other projects based on the older FTC and provide information on the biobanking of biosamples and related phenotypes. [ABSTRACT FROM AUTHOR]

Aims: To estimate birth cohort effects on alcohol consumption and abstinence in Finland and to test differences between birth cohorts in genetic and environmental sources of variation in Finnish adult alcohol use. Design The Older Finnish Twin Cohort longitudinal survey study 1975–2011. Setting: Finland. Participants: A total of 26 121 same‐sex twins aged 18–95 years (full twin pairs at baseline n = 11 608). Measurements Outcome variables were the quantity of alcohol consumption (g/month) and abstinence (drinking zero g/month). Predictor variables were 10‐year birth cohort categories and socio‐demographic covariates. In quantitative genetic models, two larger cohorts (born 1901–20 and 1945–57) were compared. Findings: Multi‐level models in both sexes indicated higher levels of alcohol consumption in more recent birth cohorts and lower levels in earlier cohorts, compared with twins born 1921–30 (all P < 0.003). Similarly, compared with twins born 1921–30, abstaining was more common in earlier and less common in more recent cohorts (all P < 0.05), with the exception of men born 1911–20. Birth cohort differences in the genetic and environmental variance components in alcohol consumption were found: heritability was 21% [95% confidence interval (CI) = 0–56%] in the earlier‐born cohort of women [mean age 62.8, standard deviation (SD) = 5.3] and 51% (95% CI = 36–56%) in a more recent cohort (mean age 60.2, SD = 3.7) at the age of 54–74. For men, heritability was 39% (95% CI = 27–45%) in both cohorts. In alcohol abstinence, environmental influences shared between co‐twins explained a large proportion of variation in the earlier‐born cohort (43%, 95% CI = 23–63%), whereas non‐shared environmental (54%, 95% CI = 39–72%) and additive genetic influences (40%, 95% CI = 13–61%) were more important among more recent cohorts of men and women. Conclusion: The contribution of genetic and environmental variability to variability in alcohol consumption in the Finnish population appears to vary by birth cohort. [ABSTRACT FROM AUTHOR]

Objective: Binge eating disorder (BED) is a clinical eating disorder that is strongly and bidirectionally related to overweight and obesity. Little is known about how subclinical features of BED relate to weight development in adolescence and young adulthood.Method: Women (n = 2825) and men (n = 2423) from the community-based longitudinal FinnTwin16 cohort participated. Seven eating-related cognitions and behaviors similar to the defining features of BED were extracted from the Eating Disorder Inventory-2 and were assessed at a mean age of 24. We used linear mixed models to assess the association of features of BED with BMI trajectories across four waves of data collection (mean ages 16, 17, 18, and 24).Results: The number of features of BED at wave 4 (age 24) was significantly associated with BMI from age 16 years onwards. Those reporting more features of BED had gained more weight throughout adolescence and into their twenties.Conclusions: Features of BED in young adulthood were preceded by steeper BMI trajectories in adolescence. A higher number of features were consistently associated with higher BMI and more weight gain. [ABSTRACT FROM AUTHOR]

Background: Developmental relationships between tobacco use and suicide-related behaviors (SRB) remain unclear. Our objective was to investigate the longitudinal associations of tobacco use in adolescence and SRB in adulthood.Methods: Using a prospective design, we examined whether tobacco use in adolescence is associated with SRB (intentional self-injury, suicide ideation) in young adulthood in a population-based sample of 1330 twins (626 males, 704 females). The baseline and follow-up data were collected by professionally administered semi-structured poly-diagnostic interviews at ages 14 and 22, respectively.Results: After adjusting for multiple potential confounders, those who reported early-onset of regular tobacco use had a significantly increased risk for intentional self-injury, such as cutting or burning, at age 22 (adjusted odds ratio [AOR] 4.57, 95% CI 1.93-10.8) in comparison to those who had not at all initiated tobacco use. Also, daily cigarette smoking at baseline was associated with future intentional self-injury (AOR 4.45, 95% CI 2.04-9.70). Early-onset tobacco use was associated with suicidal ideation in females (AOR 3.69, 95% CI 1.56-8.72) but not in males. Considering any SRB, baseline daily smokers (AOR 2.13, 95% CI 1.12-4.07) and females with early onset of regular tobacco use (AOR 3.97, 95% CI 1.73-9.13) had an increased likelihood. Within-family analyses among twin pairs discordant for exposure and outcome controlling for familial confounds showed similar, albeit statistically non-significant, associations.Conclusion: Early-onset tobacco use in adolescence is longitudinally associated with SRB (intentional self-injury and/or suicide ideation) in young adulthood, particularly among females. Further investigation may reveal whether this association has implications for prevention of SRB in adolescence and young adulthood. [ABSTRACT FROM AUTHOR]

Introduction: Genetic factors contribute to individual differences in physical activity, but it remains uncertain whether the magnitude of the genetic effects is modified by variations in home environments. We aimed to examine to what extent the psychosocial home environment in childhood and adolescence modifies the genetic influences on leisure time physical activity in young adulthood. Methods: Participants were Finnish twins (N = 3305) who reported their leisure time physical activity at age 24 yr. The psychosocial home environment was assessed by twins at ages 12, 14, and 17 yr, as well as by their parents when the twins were age 12 yr. Gene-environment interaction modeling was performed with OpenMx software. Results: Parental ratings of positive home atmosphere as well as the twins' ratings of both positive home atmosphere at age 14 yr and lower relational tensions at ages 12 and 14 yr predicted higher leisure time physical activity levels in young adulthood (regression coefficients = 0.33-0.64). Parental perceptions as well as the twins' perceptions of positive home atmosphere at ages 14 and 17 yr increased the additive genetic variation (moderation effects: 0.55, 95% confidence interval [CI] = 0.29-0.80; 0.60, 95% CI = 0.26-1.05; and 0.52, 95% CI = 0.19-0.87, respectively). The twins' ratings of positive home atmosphere at age 12 yr and lower relational tensions at ages 12 and 14 yr increased the unique environmental variation of their subsequent physical activity (moderation effects: 0.46, 95% CI = 0.19-0.60; 0.48, 95% CI = 0.29-0.64; and 0.85, 95% CI = 0.12-0.95, respectively). Conclusions: A psychosocial home environment that is warm and supportive in childhood and adolescence not only increases the mean level of subsequent leisure time physical activity in young adulthood but also modifies the genetic and environmental variances in leisure time physical activity. [ABSTRACT FROM AUTHOR]

Background: Previous epidemiological studies suggest that working-aged persons with a history of moderate-to-severe traumatic brain injury (TBI) may have an increased risk for developing neurodegenerative disease (NDD) while persons with a history of mild TBI do not. In this comprehensive nationwide study in Finland, we assessed the risk of NDD and history of moderate-to-severe TBI in the working-age population.Methods and Findings: We performed a population-based follow-up study using the Finnish Care Register for Health Care to identify all persons between the ages of 18 and 65 years hospitalized during 1987-2014 due to TBI who did not have a baseline NDD diagnosis. We compared the risk of hospitalization with NDD between persons hospitalized due to moderate-to-severe TBI (intracranial lesions) and persons hospitalized due to mild TBI (no intracranial lesions). Follow-up NDD diagnoses were recorded from 1 year following the TBI to the end of 2014. NDD diagnoses included dementia, Parkinson disease, and amyotrophic lateral sclerosis. We used a Cox proportional hazards model, adjusting for age, sex, education, and socioeconomic group, to assess the association between TBI and NDD. In total, 19,936 and 20,703 persons with a history of moderate-to-severe TBI and mild TBI, respectively, were included. The overall time at risk was 453,079 person-years (median 10 years per person). In total, 3.5% (N = 696) persons in the moderate-to-severe TBI group developed NDD compared to 1.6% (N = 326) in the mild TBI group. After adjusting for covariates, moderate-to-severe TBI was associated with an increased risk for NDD, with a hazard ratio (HR) of 1.8 (95% CI 1.6-2.1) compared to mild TBI. Of the NDD subtypes, only moderate-to-severe TBI was associated with an increased risk for dementia (HR 1.9, 95% CI 1.6-2.2). Yet, this large-scale epidemiological study does not prove that there is a causal relationship between moderate-to-severe TBI and NDD. Further, the Care Register for Health Care includes only hospitalized persons; thus, patients diagnosed with NDD in the outpatient setting may have been missed. Additional limitations include the potential for miscoding and unmeasured confounds.Conclusions: In working-aged persons, a history of moderate-to-severe TBI is associated with an increased risk for future dementia but not for Parkinson disease or amyotrophic lateral sclerosis. [ABSTRACT FROM AUTHOR]

Background: We investigated the stability and change of leisure-time physical inactivity in adult men and women during a 35-year follow-up. We also analysed the impact of long-term physical inactivity on the development of body mass index (BMI).Methods: : In this population-based cohort study, 5254 Finnish twin individuals (59% women) participated in four surveys in 1975, 1981, 1990 and 2011. Mean age at baseline was 23.9 years. Individual long-term leisure-time physical activity (LTPA) was categorized into seven classes varying from 'persistently inactive' to 'persistently active'. We used the multivariate multilevel mixed-effects linear regression model and paired-sample t-test in the analyses. Co-twin control design was used for examining within-pair associations.Results: : Of men 11%, and of women 8%, were persistently inactive. Among both sexes, the mean BMI slope trajectories were steeper among the persistently inactive and those who became inactive than among those who were persistently active. Overall, the inactive participants gained 1.4 kg/m 2 [95% confidence interval (CI) 1.2 to 1.7] more in weight than did the active participants from 1975 to 2011. Among twin pairs discordant for LTPA, the corresponding difference was 1.4 kg/m 2 (95% CI 0.83 to 2.0) in dizygotic pairs and 0.68 kg/m 2 (95% CI 0.05 to1.3) in monozygotic pairs.Conclusions: Over a 35-year time span from young adulthood, persistently inactive participants and those who had become inactive had greater weight increases than those who were persistently active. This association was also found in twin-pair analyses, although attenuated in monozygotic pairs. This may support the importance of LTPA in weight management, although further causal inference is required. [ABSTRACT FROM AUTHOR]

Background: Education is associated with health related lifestyle choices including leisure-time physical inactivity. However, the longitudinal associations between education and inactivity merit further studies. We investigated the association between education and leisure-time physical inactivity over a 35-year follow-up with four time points controlling for multiple covariates including familial confounding.Methods: This study of the population-based Finnish Twin Cohort consisted of 5254 twin individuals born in 1945-1957 (59 % women), of which 1604 were complete same-sexed twin pairs. Data on leisure-time physical activity and multiple covariates was available from four surveys conducted in 1975, 1981, 1990 and 2011 (response rates 72 to 89 %). The association between years of education and leisure-time physical inactivity (<1.5 metabolic equivalent hours/day) was first analysed for each survey. Then, the role of education was investigated for 15-year and 35-year inactivity periods in the longitudinal analyses. The co-twin control design was used to analyse the potential familial confounding of the effects. All analyses were conducted with and without multiple covariates. Odds Ratios (OR) with 95 % Confidence Intervals (CI) were calculated using logistic and conditional (fixed-effects) regression models.Results: Each additional year of education was associated with less inactivity (OR 0.94 to 0.95, 95 % CI 0.92, 0.99) in the cross-sectional age- and sex-adjusted analyses. The associations of education with inactivity in the 15- and 35-year follow-ups showed a similar trend: OR 0.97 (95 % CI 0.93, 1.00) and OR 0.94 (95 % CI 0.91, 0.98), respectively. In all co-twin control analyses, each year of higher education was associated with a reduced likelihood of inactivity suggesting direct effect (i.e. independent from familial confounding) of education on inactivity. However, the point estimates were lower than in the individual-level analyses. Adjustment for multiple covariates did not change these associations.Conclusions: Higher education is associated with lower odds of leisure-time physical inactivity during the three-decade follow-up. The association was found after adjusting for several confounders, including familial factors. Hence, the results point to the conclusion that education has an independent role in the development of long-term physical inactivity and tailored efforts to promote physical activity among lower educated people would be needed throughout adulthood. [ABSTRACT FROM AUTHOR]

Background: The role played by total cholesterol (TC) in risk for subarachnoid hemorrhage (SAH) is unclear because studies report both high and low TC each as a risk factor. We performed a systematic review to clarify associations between lipid profile and SAH. Methods: Our literature search comprised Pubmed, Scopus, and Cochrane Library databases with no language, publication year, or study type limitations. The Preferred Reporting Items for Systematic reviews and Meta-analyses (PRISMA) checklist guided our reporting. Data forms adapted from the Critical Appraisal Skills Program (CASP), and Cochrane Collaboration guidelines provided a platform for risk-of-bias evaluation. We used a random effects model to calculate pooled estimates and assessed heterogeneity with I2-statistics. Results: Of the final 21 studies reviewed, 12 were prospective and 9 retrospective. All studies assessed TC, four assessed HDL, and none LDL in risk for SAH. Heterogeneity among all, retrospective, and Asian studies was high (I2 = 79.5%, I2 = 89.0%, and I2 = 84.3%) and considerable in prospective (I2 = 46.0%). We therefore focused on qualitative analysis and found that only two studies had a low risk of bias. According to these studies high TC increases risk for SAH in men, whereas the role of HDL remained unclear. Conclusion: The low-risk-of-bias studies suggest that elevated TC levels elevate risk for SAH in men. Due to the high prevalence of hypercholesterolemia, population attributable risk (PAR) of hypercholesterolemia may exceed the PARs of smoking and hypertension in men. Apart from diabetes and obesity, the risk-factor profile of SAH seems to resemble that of other cerebrovascular diseases, at least in men. [ABSTRACT FROM AUTHOR]

Rupture of an intracranial aneurysm is the most common cause of subarachnoid haemorrhage (SAH), which is a life-threatening acute cerebrovascular event that typically affects working-age people. The exact prevalence of unruptured intracranial aneurysms (UIAs) is unknown, but at least one in 20 to 30 adults is likely to carry an asymptomatic UIA. Approximately one quarter of these UIAs rupture in a lifetime. Complex methodological challenges in conducting studies of epidemiology and risk factors for UIAs and SAH might have led to conclusions being drawn on the basis of epidemiological data of variable quality. We believe that, as a result, misconceptions about UIAs and SAH may have arisen. In this Perspectives article, we discuss three possible misconceptions about the epidemiology of UIAs and SAH, and suggest how the quality of future research could be improved. [ABSTRACT FROM AUTHOR]

The International Network of Twin Registries (INTR) aims to foster scientific collaboration and promote twin research on a global scale by working to expand the resources of twin registries around the world and make them available to researchers who adhere to established guidelines for international collaboration. Our vision is to create an unprecedented scientific network of twin registries that will advance knowledge in ways that are impossible for individual registries, and includes the harmonization of data. INTR will also promote a broad range of activities, including the development of a website, formulation of data harmonization protocols, creation of a library of software tools for twin studies, design of a search engine to identify research partners, establishment of searchable inventories of data and biospecimens, development of templates for informed consent and data sharing, organization of symposia at International Society of Twin Studies conferences, support for scholar exchanges, and writing grant proposals. [ABSTRACT FROM PUBLISHER]

INTRODUCTION: Dyspnea has not been widely used as a proxy measure of fitness. Because dyspnea score is simple to obtain, it could be a screening tool for identifying individuals with low fitness and increased mortality risk. The aim was to study how baseline dyspnea, and changes in it, predicts all-cause mortality. METHODS: The prospective Finnish Twin Cohort includes all same-sex twin pairs born in Finland before 1958. Dyspnea was measured with a four-question modified Medical Research Council scale. The level and change in dyspnea between 1975 and 1981 were used as the baseline predictors. Altogether, 21,379 twin individuals (8672 complete twin pairs) had answered dyspnea questions in 1975 and 1981. Cox proportional hazards model was used for mortality analysis starting from the 1981 response date until December 31, 2010. RESULTS: Increased mortality was observed among individuals with persistent dyspnea (dyspnea in 1975 and 1981); full covariate adjusted HR of death was 1.41 (95% confidence interval, 1.31-1.52), whereas the HR for dyspnea developers and those with dyspnea remission were 1.16 (1.05-1.25) and 1.07 (0.97-1.19), respectively, compared with asymptomatic individuals. Among healthy subjects at 1981 baseline, the corresponding HR values were 1.34 (1.16-1.54), 1.15 (0.97-1.37), and 1.05 (0.89-1.23). Within-pair analyses of death discordant pairs showed a fully adjusted HR for persistent dyspnea of 1.47 (1.23-1.77) for all twin pairs and 2.64 (1.21-5.74) for healthy monozygotic pairs. CONCLUSIONS: Persistent dyspnea predicts increased mortality during a 28-yr follow-up even among individuals without clinically overt disease known to associate with dyspnea. The dyspnea score, which can be easily obtained and correlates with fitness outcomes, could be a screening tool for identifying unfit individuals at an increased mortality risk. [ABSTRACT FROM AUTHOR]

The aim of the study was to investigate the effects of age, sex, and body mass index (BMI) on total sitting time among the Finnish twin cohort. Also, heritability and environmental factors were analysed. The final sample included 6713 twin individuals 53-67 years of age (46% men). Among them there were 1940 complete twin pairs (732 monozygotic [MZ] and 1208 dizygotic [DZ] twin pairs). Sedentary behaviour was queried with a self-reported questionnaire with multiple-choice questions about sitting time at different domains. The mean total sitting time per day was 6 hours 41 minutes (standard deviation: 2 hours 41 minutes). The total sitting time was less in women than in men (P = 0.002). Older age was associated with less total sitting time (P < 0.001). Those with higher body mass index had higher total sitting time in age and sex adjusted analysis (P < 0.001). MZ pairs were more similar for sitting time than DZ pairs, with initial estimates of heritability for the total sitting time of 35%.The influence of shared environmental factors was negligible (1%), while most (64%) of the variation could be ascribed to unique environmental factors, the latter including measurement error. [ABSTRACT FROM AUTHOR]

Background: Body mass index (BMI) is associated with subjective well-being. Higher BMI is believed to be related with lower well-being. However, the association may not be linear. Therefore, we investigated whether a nonlinear (U-shaped) trend would better describe this relationship, and whether eating disorders might account for the association in young adults. Methods: FinnTwin16 study evaluated multiple measures of subjective well-being, including life satisfaction, General Health Questionnaire (GHQ-20), satisfaction with leisure time, work, and family relationships, and satisfaction with sex life in young adulthood in the 1975-79 birth cohorts of Finnish twins (n=5240). We studied the relationship between indicators of subjective well-being and BMI both in full birth cohorts and in subgroups stratified by lifetime DSM-IV eating disorders. Results: We found an inverse U-shaped relationship between all indicators of subjective well-being and BMI in men. There was no overall association between BMI and subjective well-being in women. However, there was an inverse U-shaped relationship between BMI and indicators of subjective well-being in women with a lifetime eating disorder and their healthy female co-twins. Subjective well-being was optimal in the overweight category. Conclusions: Both underweight and obesity are associated with impaired subjective well-being in young men. The BMI reflecting optimal subjective well-being of young men may be higher than currently recognized. Categorization of body weight in terms of BMI may need to be reassessed in young men. BMI and subjective well-being are related in women with a lifetime eating disorder, but not in the general population of young women. [ABSTRACT FROM AUTHOR]

In 2002 and 2006, review papers have described the Finnish Twin Cohort and studies conducted on these population-based, longitudinal data sets with extensive follow-up data. Three cohorts have been established: the older twin cohort in the 1970s, and the Finntwin12 and Finntwin16 studies initiated in the 1990s. The present review provides on update on the latest data collections conducted since the previous review. These cover the fourth waves of data collection in the older cohort (twins born before 1958) and Finntwin12 (twins born 1983–1987). The fifth wave of data collection in Finntwin16 (twins born 1975–1979) also included assessments of their spouses/partners. An analysis of mortality in the older cohort from 1975 to 2009 indicates that the mortality of adult twins (as individuals) does not differ from the population at large. Based on the cohorts, many sub-studies with more detailed phenotyping and collection of omics data have been conducted or are in progress. We also contribute to numerous national and international collaborations. [ABSTRACT FROM AUTHOR]

Background: Chest circumference (CC) is suggested to be a good indicator of early life nutrition, but little is known on the heritability of CC. Thus we analysed the effects of genetic and environmental factors on the development of CC in Japanese infants. Methods: CC was measured longitudinally from birth until 1 year of age in a cohort of 211 monozygotic and 160 dizygotic complete Japanese twin pairs born in 1989-2002. The data were analysed using applications of structural linear equation modelling for twin data. Results: No sex-specific differences in the variance components were found. Environmental factors unique to each twin explained the major part of the variation of CC at birth whereas environmental factors shared by co-twins were more important at 1-3 months of age. From 3 months of age, the effect of genetic factors become steadily stronger and they explained the majority of the variation at 1 year of age. Strong genetic continuity in the development of CC was found, but also new sets of genes were activated during the first year of life. The origin of the environmental part of the variation could be tracked before 3 months of age. A substantial part of common and specific environmental factors affecting CC affected also birthweight. Conclusions: CC is sensitive to intrauterine environmental factors, but these effects diminish during the first year of life, at least if postnatal environment is good. CC can be a useful indicator when identifying newborns who have suffered suboptimal pre-natal conditions. [ABSTRACT FROM AUTHOR]

Summary: Robust sex differences in some spatial abilities that favor males have raised the question of whether testosterone contributes to those differences. There is some evidence for prenatal organizational effects of testosterone on male-favoring spatial abilities, but not much is known about the role of pubertal testosterone levels on adult cognitive abilities. We studied the association between pubertal testosterone (at age 14) and cognitive performance in young adulthood (at age 21–23), assessing male-favoring, female-favoring, and sex-neutral cognitive domains in a population-based sample of 130 male and 178 female twins. Pubertal testosterone was negatively associated with performance in the Mental Rotation Test in young adult men (r =−.27), while among women no significant associations between testosterone and cognitive measures were detected. The significant association among men remained after controlling for pubertal development. Confirmatory within-family comparisons with one-sided significance testing yielded a negative correlation between twin pair differences in testosterone levels and Mental Rotation Test performances in 35 male twin pairs (r =−.32): the twin brother with higher testosterone performed less well on the Mental Rotation Test. That association was evident in 18 pairs of dizygotic male twin pairs (r =−.42; analysis controlling for shared environmental effects). In contrast, the association of differences was not evident among 17 monozygotic male twin pairs (r =−.07; analysis controlling for shared genetic influences). Results suggest that pubertal testosterone levels are related specifically to male-favoring spatial ability and only among men. Within-family analyses implicated possible shared genetic effects between pubertal testosterone and mental rotation ability. [Copyright &y& Elsevier]

Most studies on lung function heritability have been conducted in smokers and non-smokers using cross-sectional study design. Smoking patterns may, however, confound the contribution of genetic factors. We investigated heritability of forced expiratory volume in one second (FEV1), forced vital capacity (FVC), and FEV1/FVC ratio longitudinally, excluding the effects of smoking. A sample of never smoking female twins (n = 374), aged 63-76 at baseline, answered health questionnaires and attended spirometry in years 2000 and 2003. Bivariate structural equation modeling, restricted to adequate spirometry performances (baseline n = 339, follow-up n = 252), was used to estimate genetic and environmental influences on consecutive measurements of FEV1, FVC, and FEV1/FVC. The best-fitting models included additive genetic and non-shared environmental effects. Heritability estimates of 32% and 36% for FEV1, 41% and 37% for FVC, while 46% and 16% for FEV1/FVC were found at baseline and at follow-up. Genetic correlation between FEV1 and FEV1/FVC heritability estimates approached unity, whereas correlation between FVC estimates was 0.80. Environmental correlations were 0.69 for FEV1, 0.62 for FVC, and 0.07 for FEV1/FVC. In never smokers, additive genetic and non-shared environmental effects explain the inter-individual variations in FEV1, FVC, and FEV1/FVC. One third of the variation in FEV1 and FVC is explained by genetic and two thirds by environmental effects. Between 2000 and 2003, environmental effects on FEV1/FVC changed, and the proportion of variance explained by environmental effects increased remarkably. Genetic effects on FEV1 and FEV1/FVC are common to consecutive measurements, whereas at follow-up, new genetic factors explained 14% of the observed variance in FVC. [ABSTRACT FROM AUTHOR]

Background: Genetic factors explain a major part of the variation of adult stature, but little is still known on the genetics of growth, especially in non-Caucasian populations. Aim: To analyse the quantitative genetics of pre-pubertal growth in Japanese children. Subjects and methods: Data from birth until 11 years of age were collected on 349 complete twin pairs based on previously recorded height measures. The data were analysed using two different multivariate models by the Mx statistical package. Results: No major sex differences were found and thus boys and girls were analysed together. Since 1 year of age, genetic factors explained from 42--71% and environmental factors shared by co-twins from 14--33% of the variation of height. Genetic continuity of height was high and 75% of the genetic variance was shared since 1 year of age. Environmental factors affecting height showed weaker correlations between early and late childhood than genetic factors. Conclusion: Growth from early to late childhood is largely regulated by the same set of genes. However, also environmental factors shared by co-twins are important for growth. Identifying specific environmental factors affecting growth has potentially important public health implications, even in an affluent society such as Japan. [ABSTRACT FROM AUTHOR]

Background: antioxidants might protect against oxidative stress, which has been suggested as a cause of aging.Methods: the Alpha-Tocopherol-Beta-Carotene (ATBC) Study recruited males aged 50–69 years who smoked at least five cigarettes per day at the baseline. The current study was restricted to participants who were followed up past the age of 65. Deaths were identified in the National Death Registry (1,445 deaths). We constructed Kaplan–Meier survival curves for all participants, and for four subgroups defined by dietary vitamin C intake and level of smoking. We also constructed Cox regression models allowing a different vitamin E effect for low and high age ranges.Results: among all 10,837 participants, vitamin E had no effect on those who were 65–70 years old, but reduced mortality by 24% when participants were 71 or older. Among 2,284 men with dietary vitamin C intakes above the median who smoked less than a pack of cigarettes per day, vitamin E extended lifespan by 2 years at the upper limit of the follow-up age span. In this subgroup, the survival curves of vitamin E and no-vitamin E participants diverged at 71 years. In the other three subgroups covering 80% of the participants, vitamin E did not affect mortality.Conclusions: this is the first study to strongly indicate that protection against oxidative stress can increase the life expectancy of some initially healthy population groups. Nevertheless, the lack of effect in 80% of this male cohort shows that vitamin E is no panacea for extending life expectancy. [ABSTRACT FROM AUTHOR]

We analyzed the genetic architecture of prepubertal development of relative weight to height in 216 monozygotic and 159 dizygotic complete Japanese twin pairs (52% girls). Ponderal index at birth (kg/m) and body mass index (BMI, kg/m) from 1 to 11 years of age were used. Additive genetic factors explained the major proportion (52-74%) of the variation of BMI from 1 to 11 years of age. Environmental factors common to both co-twins also showed some effect (7-28%), but at most ages this was not statistically significant. Strong genetic tracking was found for BMI from 1 to 11 years of age, but there was also evidence for a persistent effect of common environmental factors. Our results suggest that the genetic architecture of BMI development in the Japanese population is generally similar to that found in previous twin studies in Caucasian populations. [ABSTRACT FROM AUTHOR]

The lack of sex difference in left-handedness in Scandinavian countries reported by Papadatou-Pastou, Martin, Munafò, and Jones (2008) is questioned. We investigated the sex difference in left-handedness in two Finnish, one Norwegian, and one Swedish population-based sample not included in the Papadatou-Pastou et al. (2008) meta-analysis. The male-to-female odds ratio across these samples was I .34 (95% confidence interval = 1 .18, 1.51), indicating that the sex difference in left-handedness also exists in Scandinavian countries. Studies show that a similar sex difference in left-handedness is evident in twins as well. Overall, we challenge the contentions of Papadatou-Pastou et al. (a) that a lack of sex differences in left-handedness actually exists in Scandinavia or (b) that any such lack of differences could relate to extremely low levels of cultural masculinity in Scandinavian societies. [ABSTRACT FROM AUTHOR]

OBJECTIVES: To examine whether hearing acuity correlates with walking ability and whether impaired hearing at baseline predicts new self-reported walking difficulties after 3 years. DESIGN: Prospective follow-up. SETTING: Research laboratory and community. PARTICIPANTS: Four hundred thirty-four women aged 63 to 76. MEASUREMENTS: Hearing was measured using clinical audiometry. A person was defined as having a hearing impairment if a pure-tone average of thresholds at 0.5 to 4 kHz in the better ear was 21 dB or greater. Maximal walking speed was measured over 10 m (m/s), walking endurance as the distance (m), covered in 6 minutes and difficulties in walking 2 km according to self-report. RESULTS: At baseline, women with hearing impairment (n=179) had slower maximal walking speed (1.7 ± 0.3 m/s vs 1.8 ± 0.3 m/s, P=.007), lower walking endurance (520 ± 75 m vs 536 ± 75 m, P=.08), and more selfreported major difficulties in walking 2 km (12.8% vs 5.5%, P=.02) than those without hearing impairment. During follow-up, major walking difficulties developed for 33 participants. Women with hearing impairment at baseline had a twice the age-adjusted risk for new walking difficulties as those without hearing impairment (odds ratio=2.04, 95% confidence interval=0.96–4.33). CONCLUSION: Hearing acuity correlated with mobility, which may be explained by the association between impaired hearing and poor balance and greater risk for falls, both of which underlie decline in mobility. Prevention of hearing loss is not only important for the ability to communicate, but may also have more wide-ranging influences on functional ability. [ABSTRACT FROM AUTHOR]

Introduction:: The main body of smoking behavior research has targeted primarily moderate and heavy smoking. This study aimed to define characteristics of daily light smoking and to examine the consistency of this smoking pattern. [ABSTRACT FROM PUBLISHER]

Abstract: Background: Obesity is related to an increased risk of several forms of cancer. However, findings from studies on haematological malignancies are inconsistent. Methods: We used prospectively collected data from two Swedish twin cohorts and the Finnish Twin Cohort (in total 70,067 persons) to study the effects of overweight and obesity on the development of leukaemia, non-Hodgkin lymphoma, Hodgkin’s lymphoma and myeloma. The cohorts were followed from baseline through 2002 (Sweden) and through 2004 (Finland). Results: We found a risk increase of myeloma with a relative risk (RR) of 2.1 (95% confidence interval [CI] 1.1–3.7) among obese persons, a RR of 2.5 (1.0–6.2) for chronic myeloid leukaemia and a RR of 2.7 (0.8–9.6) for acute lymphoblastic leukaemia among overweight persons as compared to normal-weighted ones. Conclusions: Our results add further evidence suggesting that overweight and obesity may have an impact on some haematological malignancies, in particular myeloma. [Copyright &y& Elsevier]

Background. The purpose of the present study was to examine, first, whether hearing acuity predicts falls and whether the potential association is explained by postural balance and, second, to examine whether shared genetic or environmental effects underlie these associations. Methods. Hearing was measured using a clinical audiometer as a part of the Finnish Twin Study on Aging in 103 monozygotic and 114 dizygotic female twin pairs aged 63-76 years. Postural balance was indicated as a center of pressure (COP) movement in semitandem stance, and participants filled in a fall-calendar daily for an average of 345 days after the baseline. Results. Mean hearing acuity (better ear hearing threshold level at 0.5-4 kHz) was 21 dB (standard deviation [SDI 12). Means of the COP velocity moment for the best to the poorest hearing quartiles increased linearly from 40.7 mm²/s (SD 24.4) to 52.8 mm2/s (SD 32.0) (p value for the trend = .003). Altogether 199 participants reported 437 falls. Age-adjusted incidence rate ratios (IRR5) for falls, with the best hearing quartile as a reference, were 1.2 (95% confidence interval [CI] = 0.4-3.8) in the second, 4.1(95% Cl = 1.1-15.6) in the third, and 3.4 (95% Cl = 1.0-11.4) in the poorest hearing quartiles. Adjustment for COP velocity moment decreased IRRs markedly. Twin analyses showed that the association between hearing acuity and postural balance was not explained by genetic factors in common for these traits. Conclusion. People with poor hearing acuity have a higher risk for falls, which is partially explained by their poorer postural control. Auditory information about environment may be important for safe mobility. [ABSTRACT FROM AUTHOR]

To examine whether vitamin C rich food consumption and related vitamin C intake are associated with the risk of tuberculosis, the authors analyzed 167 incident cases of tuberculosis during a median follow-up time of 6.7 years in a clinical trial cohort of 26,975 Finnish men for whom they had baseline dietary data. A highly statistically significant inverse association between calculated vitamin C intake and the incidence of tuberculosis was found, but adjustment for non-dietary factors weakened the association to nonsignificant. Furthermore, the risk of tuberculosis decreased with increasing intake of fruits, vegetables, and berries independent of vitamin C intake. Subjects who had dietary vitamin C intake >90 mg/day and who consumed more than the average amount of fruits, vegetables, and berries had a significantly lower risk of tuberculosis (adjusted relative risk = 0.40; 95% confidence interval 0.24, 0.69). Associations between dietary vitamin C intake and occurrence of various diseases without proper control of confounding have often been interpreted as causal. These findings show that such associations can be confounded even by some other dietary components. Lower tuberculosis incidence in subjects who consumed more fruits, vegetables, and berries poor in vitamin C suggests that other compounds in such a diet may reduce the risk of tuberculosis. Am J Epidemiol 1999; 150: 632-41. [ABSTRACT FROM PUBLISHER]

Abstract: We studied whether factors related to type of sport participated in as young adults and level of and changes in physical activity later in life predict changes in mood as well as functioning during a 6-year follow-up. A cohort of male Finnish former athletes (N =504), referents (N =349) was followed up for changes in physical activity, in relation to subsequent self-reported mood and functioning of daily living in 1985, 1995, and 2001. The mean age of the cohort was 68.6 years in 2001. Multinomial logistic regression analysis was used to assess changes in mood and functioning between 1995 and 2001 in relation to baseline values and changes in exposure variables and covariates. A low level of physical activity in 1985 predicted a decrease in physical functioning between 1995 and 2001 in the lowest physical activity compared to the highest quintile as well as poor physical functioning at the end of follow-up in 2001. An increase in physical activity between 1985 and 1995 protected against onset of anxiety between 1995 and 2001. Physical activity for elderly seems to have an important role in reducing the progress of deficiencies in physical functioning and in preventing onset of anxiety. [Copyright &y& Elsevier]

Objective: The authors tested the hypothesis that either prenatal feminization or masculinization hormone influences in utero or later socialization affects the risk for anorexia and bulimia nervosa and disordered eating in members of opposite-sex twin pairs. Method: Finnish twins (N=2,426 women, N=1,962 men with known zygosity) from birth cohorts born 1974-1 979 were assessed at age 22 to 28 years with a questionnaire for eating disorder symptoms. Based on the questionnaire screen, women (N=292), men (N53), and their cotwins were interviewed to assess diagnoses of anorexia nervosa and bulimia nervosa (per DSM-IV and broad criteria). Results: In women from opposite-sex twin pairs, the prevalence of DSM-IV or broad anorexia nervosa was not significantly different than that of women from monozygotic pairs or same-sex dizygotic pairs. Of the five male anorexia nervosa probands, only one was from an opposite-sex twin pair. Bulimia nervosa in men was too rare to be assessed by zygosity; the prevalence of DSM-IV or broad bu- limia nervosa did not differ in women from opposite-versus same-sex twin pairs. In both sexes, the overall profile of indicators on eating disorders was rather similar between individuals from opposite- and same-sex pairs. Conclusions: The authors found little evidence that the risk for anorexia nervosa, bulimia nervosa, or disordered eating was associated with zygosity or sex composition of twin pairs, thus making it unlikely that in utero femininization or masculinization or socialization effects of growing up with an opposite-sex twin have a major influence on the later development of eating disorders. [ABSTRACT FROM AUTHOR]

Background Coffee is a highly popular drink associated with the pathogenesis of several diseases and the use of tobacco and alcohol. Considering the worldwide consumption, coffee has a substantial effect on individual wellbeing and public health. The role of genetic factors contributing to interindividual differences and their stability in coffee use is not well known. Aims We analysed the heritability of coffee consumption and its stability in a large population-based sample of Finnish twins. Design In 1975 and 1981 a postal questionnaire on coffee consumption was sent to all Finnish same-sex twin pairs born before 1958. Responses were obtained from 10 716 complete twin pairs in 1975 (3409 monozygotic and 7307 dizygotic), of whom 8124 also responded in 1981. The data were analysed using classical twin modelling based on linear structural equations. Findings Additive genetic and unique environmental factors affected coffee drinking, whereas shared environmental factors did not show any effect. Heritability of coffee consumption, adjusted for age and sex, was estimated as 0.56 in 1975 and 0.45 in 1981. Coffee consumption showed a moderate correlation between these two time-points ( r = 0.58 in men and 0.55 in women). Genetic factors affecting coffee consumption were stable: additive genetic correlations were 0.84 in men and 0.83 in women, whereas unique environmental correlations were moderate (0.45 and 0.36). Additive genetic factors had the highest contribution in young adults. Conclusions Coffee consumption is affected by both additive genetic and unique environmental factors, each of which plays an almost equally important role. The long-term stability of coffee consumption is affected mainly by a stable set of additive genetic factors. [ABSTRACT FROM AUTHOR]

The purpose of the present study was to examine the relative contribution of genetic and environmental effects on the air-conducted hearing threshold levels at low (0.125-0.5 kHz), mid (1-2 kHz), and high (4-8 kHz) frequencies separately for the better and worse hearing ear in older women. We also examined the distribution of audiogram configurations. Data was analysed using quantitative genetic modelling. As part of the Finnish twin study on aging (FITSA), hearing was measured in 103 monozygotic and 114 dizygotic female twin pairs aged 63-76 years. Approximately every third subject had a flat type, and two-thirds a descending type of audiogram configuration. No significant difference was observed in the distribution of audiogram configurations between zygosity groups. In the better ear, additive genetic effects accounted for 64%-74% of the total variance at different frequencies. For the worse ear, environmental effects were larger. Although overall heritability is rather constant across the frequency spectrum, it is noteworthy that at low and high frequencies frequency-specific genetic and environmental effects together accounted for the majority of the total variance. [ABSTRACT FROM AUTHOR]

Background: Finland and Sweden are neighbouring countries with a substantially higher incidence and mortality from coronary heart disease (CHD) in Finland. Migration from Finland to Sweden has resulted in a population of about 187,000 Finnish immigrants, with a higher risk of CHD than Swedes. The aim of the present study was to analyse the prevalence of CHD in migrants to Sweden compared with co-twins remaining in Finland. Methods: The study population consisted of twin pairs of the Finnish Twin Cohort Study where at least one twin had lived one year or more in Sweden, including 1,534 subjects and 251 complete twin pairs discordant regarding residency in Sweden. Emigrant twins were compared with non-migrant co-twins regarding prevalence of CHD in 1998. CHD prevalence was assessed by self-reported questionnaires validated using information from a clinical examination. Results: Self-reported CHD showed a good correspondence with clinical diagnosis. Differences in social and behavioural risk factors for CHD among men were small but emigrants were more physically active than non-migrants. Female emigrants had less overweight and better education, but were more often working class than non-migrants. Intra-pair comparisons restricted to migration discordant pairs showed a tendency towards a reduced prevalence of CHD in the migrant co-twins (0.6; 0.3-1.4). In analyses of all subjects disregarding pair status, emigrants showed a reduced prevalence of CHD compared with subjects always living in Finland (0.6; 0.4-0.9). Conclusion: Emigration from Finland to Sweden may be associated with a reduced prevalence of CHD. The causes are most likely multifactorial and may involve changes in dietary habits, physical activity, psychosocial factors, and inflammation. [ABSTRACT FROM AUTHOR]

Aims To control for familial confounds, we studied the association between adolescent physical activity and later smoking in twin siblings discordant for their baseline physical activity. Design and measurements In this prospective population-based twin study, we asked whether persistent physical activity/inactivity in adolescence (assessed at 16, 17 and 18.5 years) predicted questionnaire-reported daily smoking at ages 22–27. Twins who, on the three baseline questionnaires, consistently reported frequent leisure physical activity (more than three times weekly) were classified as persistent exercisers, those who exercised less than three times monthly were called persistently inactive, others were occasional exercisers. Setting Finland. Participants A total of 4240 individuals, including 1870 twin pairs. Findings In analyses of individual twins, compared to persistent activity, persistent physical inactivity predicted increased risk of daily smoking (age- and sex-adjusted odds ratio 5.53, 95% confidence interval 3.88–7.88, P < 0.001). The risk remained elevated even after excluding all those who had smoked 50 cigarettes or more life-time at baseline and adjusted for educational level in adolescence. In within-pair analyses compared to the active members of discordant twin pairs, the physically inactive co-twins had increased risk of future daily smoking (sex-adjusted odds ratio 3.39, 95% confidence interval 1.56–7.39, P = 0.002). Conclusions Persistent physical inactivity in adolescence relates to adult smoking, even after familial factors are taken into account. [ABSTRACT FROM AUTHOR]

We enrolled more than 3500 same-sex twinsfrom 5 consecutive Finnish birth cohorts into a longitudinal study as each cohort reached age 16. Twins completed the Psychopathic Deviate (Pd) Scale of the Minnesota Multiphasic Personality Inventory at baseline, Sensation Seeking Scale items as each cohort reached age 17, and later, at average ages 18.5 and 25, the Rutgers Alcohol Problem Index (RAPI). Using raw maximum likelihood estimation, we fit a Cholesky model to the 4 variables assessed at 4 ages across the 4 twin types; we estimated genetic and environmental influences on the stability of alcohol problems across development and the genetic and environmental contributions to predictive correlations between adolescent personality and later alcohol-related behavior problems. With one exception, the phenotypic, genetic, and environmental correlations were very similar for males and females. The exception was that the lagged associations of Pd and RAPI reflect a higher genetic correlation among males than females and a higher environmental correlation among females than males. Our analyses suggest that developmental changes underlying variation in alcohol problems from late adolescence to early adulthood differ for males and females. In males, the main change is decreased variation due to shared environmental effects; the magnitude of genetic effects is stable over time, and the high genetic correlation, .95, suggests that the same genetic influences are important at both ages. Among females, in contrast, genetic influences decline in magnitude from age 18 to 25, and at least part of the genetic effect evident at age 25 differs from the genetic effect evident at age 18. [ABSTRACT FROM AUTHOR]

Cohort studies are essential for conducting large studies of multiple exposures and outcomes in humans. Recently, the ability to combine data from multiple cohorts in, for example, meta-analyses, and the willingness in the genetics community to collaborate to enable replication studies has led to many new insights into the genetic and environmental determinants of human health and behaviors. The contribution of Professor Nicholas Martin to the development of cohort studies, particularly of twin and twin-family studies, over a period of several decades is reviewed. He has contributed to the development and use of both Australian and international resources. The contributions of Australian twin studies to genomewide association projects are multiple, and across multiple domains, from biomarkers, lifestyle and behavior to disorders and disease. [ABSTRACT FROM AUTHOR]

In studies on the Finnish Twin Cohorts, genetic and environmental determinants of common, complex diseases, and their behavioral risk factors have been investigated in Finland. In 1974, the older twins were identified, with a total of 13,888 like-sexed pairs of known zygosity. They have participated since 1975 in mail surveys, clinical examinations for subsamples, have been used to recruit families, and have been followed up for morbidity using national medical registers. Opposite twin pairs were added later. Two longitudinal studies of adolescent twins and their families, known as the FinnTwin12 and FinnTwin16 studies, have focused on determinants of health-related behaviors and disease in adolescents and young adults. This article describes current, ongoing data collection and analyses. [ABSTRACT FROM AUTHOR]

To examine the genetic and environmental sources of variation in self-rated health (SRH) in older female twins and to explore the roles of morbidity, functional limitation, and psychological well-being as mediators of genetic and environmental effects on SRH.Cross-sectional analysis of twin data.Research laboratory.One hundred two monozygotic and 115 dizygotic female twin pairs aged 63 to 76.SRH was categorized as good, average, or poor. Morbidity was described using a physician-assessed disease-severity scale together with information about the presence of diabetes mellitus and cancer. Maximal walking speed measured over 10 m was used to assess physical functional limitation; the Mini-Mental State Examination and the Center for Epidemiologic Studies Depression Scale were used to characterize psychological well-being. The contributions of genetic and environmental (defined as familial (shared by siblings) or nonshared (unique to each sibling)) effects were assessed using univariate and multivariate structural equation modeling of twin data.SRH did not have its own specific genetic effect but shared a genetic component in common with the genetic components underlying liability to disease severity, maximal walking speed, and depressive symptoms. It accounted for 64% of the variation in SRH, with environmental effects accounting for the remaining variation.The current results suggest that there are no specific genetic effects on SRH but rather that genetic influences on SRH are mediated through genetic influences affecting chronic diseases, functional limitation, and mood. [ABSTRACT FROM AUTHOR]

We examined associations of testosterone (T) and alcohol use in adolescent twin brothers, conducting both between- and within-family analyses. The twins completed semi-structured interviews, provided two saliva samples to assay T, and reported their drinking patterns and pubertal development. We adjusted T levels for diurnal/seasonal effects and association with pubertal maturation. In analyses of twins as individuals, higher T levels characterized boys reporting ever drinking, more frequent intoxication, high density drinking, more alcohol symptoms, and diagnosed alcohol dependency on interview. Adjusting for pubertal development, only associations with symptom count and diagnosis remained significant. The association with frequent intoxication replicated among drinking-discordant twin brothers, effectively ruling out between-family confounds, but that association was not significant after adjustment for pubertal development. The phenotypic correlation between T and pubertal maturation is largely genetic, inviting study of the magnitude and meaning of linkages between testosterone and symptoms of alcoholism on follow-up in early adulthood. [ABSTRACT FROM AUTHOR]

Background: While physical health has improved considerably over recent decades in Finland, the disease burden of mental health, especially that of depression, has become increasingly demanding. However, we lack long-term data on the natural course of subjective well-being in the general population. The aim of this study was to investigate the long-term course of self-reported life satisfaction. Methods: This was a 15-year prospective cohort study on a nationwide sample of adult Finnish twins (N = 9679), aged 18-45 and healthy at baseline, who responded to postal questionnaires in 1975, 1981 and 1990 including a 4-item life satisfaction scale (happiness/easiness/interest in life and feelings of loneliness). Life satisfaction score (range: 4-20) was classified into three categories: satisfied (4-6), intermediate (7-11) and dissatisfied group (12-20). The associations between life satisfaction scores during the follow-up were studied with linear/logistic regression. Results: Moderate stability and only a slight effect of age or birth-cohort on mean life satisfaction score (LS) were detected. In 1990, 56% of all and 31% of the dissatisfied remained in the same LS category as at baseline. Only 5.9% of the study subjects changed from being satisfied to dissatisfied or vice versa. Correlations between continuous scores (1975, 1981 and 1990) were 0.3-0.4. Baseline dissatisfaction (compared to satisfaction) predicted dissatisfaction in 1981 (OR = 10.4; 95%CI 8.3-13.1) and 1990 (5.6; 4.6-6.8). Multiple adjustments decreased the risk only slightly. Conclusions: Life satisfaction in adult Finns was moderately stable during 15 years. Among an identifiable group (i.e. the dissatisfied) life dissatisfaction may become persistent, which places them at a greater risk of adverse health outcomes. [ABSTRACT FROM AUTHOR]

Objective: The aim of this study was to investigate the cross-sectional and longitudinal relationship between life satisfaction and depressive symptoms in healthy adults.Method: This is a 15-year prospective cohort study with a nationwide sample of healthy Finnish adults (N = 9679), aged 18-45, who responded to postal questionnaires in 1975, 1981 and 1990 including a 4-item life satisfaction (LS) scale (range 4-20) and, in 1990, the 21-item Beck Depression Inventory (BDI).Results: A strong linear association was found between concurrent LS and BDI scales (r = 0.6). With an LS cut-off point of 11/12, moderate/severe depression (BDI > or = 19) was detected with 87% sensitivity, 88 % specificity and a 94% area under the ROC curve. Longitudinally, a strongly increased risk of moderate/severe depression in 1990 was observed among the dissatisfied (LS 12-20) compared with the satisfied (LS 4-6) in 1975 (OR = 6.7; 95 %CI 4.2-10.9) and in 1981 (OR = 10.4; 6.1-17.6).Conclusion: The 4-item LS scale can identify a group of healthy people from the general population with a high risk of having or developing depressive symptoms. Since low life satisfaction also indicates an elevated risk of other adverse health outcomes, the assessment of subjective well-being should be encouraged both in surveys and in clinical practice. [ABSTRACT FROM AUTHOR]

Finland has the world's highest incidence of type 1 diabetes, and it is steadily increasing. We determined concordance rates and estimated heritability for type 1 diabetes in the Finnish Twin Cohort, a population-based twin cohort of 22,650 twin pairs. In addition, we studied age of onset in the first affected twin and discordance time between concordant twin pairs. Finnish twins born between 1958 and 1986 were followed for type 1 diabetes until 1998. We identified 228 twin pairs with type 1 diabetes: 44 monozygotic (MZ), 183 dizygotic (DZ), and 1 pair with unknown zygosity. The pairwise concordance for type 1 diabetes was 27.3% (95% CI 22.8-31.8) in MZ and 3.8% (2.7-4.9) in DZ twins. The probandwise concordance was 42.9% (26.7-59.2) and 7.4% (2.2-12.6), respectively. The longest discordance times were 6.9 years among concordant MZ twins and 23.6 years among DZ twins. The risk for type 1 diabetes was highest in cotwins of the index twins diagnosed at a very young age. The model with additive genetic and individual environmental effects was the best-fitting liability model, with 88% of phenotypic variance due to genetic factors and the remaining variance due to unshared environmental factors. In conclusion, these nationwide twin data demonstrated high genetic liability for type 1 diabetes. Early-onset diabetes increases the risk in cotwins. However, the majority of affected MZ twin pairs remain discordant for type 1 diabetes. [ABSTRACT FROM AUTHOR]

Examines the femininity and fertility of girls with twin brothers in Finland. Impact of the prenatal exposure to the androgen of twin brothers on the attitude of the girls; Differences between sisters from same- and opposite-sex twin pairs; Occurrence of gender development in children.