Browsing by Subject "Twins"

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  • Dickerman, Barbra A.; Markt, Sarah Coseo; Koskenvuo, Markku; Pukkala, Eero; Mucci, Lorelei A.; Kaprio, Jaakko (2016)
    Purpose Alcohol intake may be associated with cancer risk, but epidemiologic evidence for prostate cancer is inconsistent. We aimed to prospectively investigate the association between midlife alcohol intake and drinking patterns with future prostate cancer risk and mortality in a population-based cohort of Finnish twins. Methods Data were drawn from the Older Finnish Twin Cohort and included 11,372 twins followed from 1981 to 2012. Alcohol consumption was assessed by questionnaires administered at two time points over follow-up. Over the study period, 601 incident cases of prostate cancer and 110 deaths from prostate cancer occurred. Cox regression was used to evaluate associations between weekly alcohol intake and binge drinking patterns with prostate cancer risk and prostate cancer-specific mortality. Within-pair co-twin analyses were performed to control for potential confounding by shared genetic and early environmental factors. Results Compared to light drinkers ( Conclusion Heavy regular alcohol consumption and binge drinking patterns may be associated with increased prostate cancer risk, while abstinence may be associated with increased risk of prostate cancer-specific mortality compared to light alcohol consumption.
  • Piirtola, Maarit; Kaprio, Jaakko; Silventoinen, Karri; Svedberg, Pia; Korhonen, Tellervo; Ropponen, Annina (2017)
    To investigate longitudinal associations of smoking and a change in smoking status with leisure-time physical inactivity. In addition, to control whether familial confounding (genetics and shared environment) influences the associations. Data were based on the population-based Finnish Adult Twin Cohort of 5254 twin individuals born in 1945-1957 (41% men) and who participated in all four surveys over a 35-year follow-up (1975-2011). Logistic and conditional logistic regression models with multiple covariates were used for analyses. Compared to never-smokers, long-term daily smokers (1975-1990) had the highest likelihood for both long-term inactivity and to change into inactive by 2011. Recurrent smoking was associated with long-term inactivity. Instead, in comparison to persistent daily smokers, quitting smoking decreased the likelihood of becoming physically inactive at leisure time. The associations remained in the analyses which accounted for multiple covariates and/or familial confounding. Daily smoking increases the likelihood of remaining or becoming physically inactive over the decades. Our results emphasize not only the importance of preventing smoking initiation, but also to support early smoking cessation in promotion of lifelong physical activity.
  • Minkkinen, Sara (Helsingin yliopisto, 2021)
    Tarkoituksenamme oli selvittää, miten nuorten aikuisten oma ja heidän vanhempiensa ongelmallinen alkoholinkäyttö on yhteydessä kehotyytymättömyyteen ja ahmimishäiriöoireisiin nuorella aikuisiällä. Aineistonamme oli suomalaisia kaksosia ja heidän vanhempiaan koskeva valtakunnallinen etenevä kohorttitutkimus FinnTwin16, josta riittävät tiedot tutkimuksemme suorittamiselle löytyi 1938 naiselta ja 1616 mieheltä sekä 1994 äidiltä ja 1994 isältä. Mittasimme vanhempien ongelmallista alkoholinkäyttöä Malmö-muokatulla Michiganin alkoholismin seulontatutkimuksella (Mm-MAST), kun kaksoset olivat 16-vuotiaita. Keskimäärin 24-vuoden ikäisinä kaksoset täyttivät syömishäiriökyselystä (Eating Disorder Inventory-2) kehotyytymättömyyttä ja ahmimishäiriöoireita koskevat osuudet sekä pidennetyn version Mm-MAST:sta, jolla selvitimme kaksosten omaa ongelmallista alkoholikäyttöä. Lineaarisella regressioanalyysillä arvioimme yhteyttä ongelmallisen alkoholinkäytön sekä kehotyytymättömyys- ja ahmimishäiriöoirepisteiden välillä. Hyödynsimme lineaarista regressioanalyysiä myös mediaatioanalyyseissä ja sekoittavien tekijöiden vakioinneissa. Yhteys vanhempien ongelmallisen alkoholinkäytön ja kaksosten kehotyytymättömyyden välillä oli mitättömän pieni (b = 0,028 naisille; 0,016 miehille), kuten myös yhteys vanhempien ongelmallisen alkoholinkäytön ja kaksosten ahmimishäiriöoireiden välillä (b = 0,012 naisille; 0,0040 miehille). Yhteys kaksosten oman ongelmallisen alkoholinkäytön ja kehotyytymättömyyden (b = 0,070 naisille; 0,043 miehille) sekä ahmimishäiriöoireiden (b = 0,090 naisille; 0,079 miehille) välillä oli kohtuullinen, eikä täysin selittynyt sekoittavien tekijöiden vakioinneilla. Emme löytäneet tukea hypoteesille, että vanhempien ongelmallinen alkoholinkäyttö vaikuttaisi nuorten aikuisten kehotyytymättömyyteen tai ahmimishäiriöoireisiin edes epäsuorasti nuorten aikuisten oman ongelmallisen alkoholinkäytön kautta. Sen sijaan nuorten aikuisten oma ongelmallinen alkoholinkäyttö oli yhteydessä suurempaan kehotyytymättömyyteen ja ahmimishäiriöoireiluun nuorella aikuisiällä.
  • Skytthe, Axel; Harris, Jennifer R.; Czene, Kamila; Mucci, Lorelei; Adami, Hans-Olov; Christensen, Kaare; Hjelmborg, Jacob; Holm, Niels V.; Nilsen, Thomas S.; Kaprio, Jaakko; Pukkala, Eero (2019)
    The Nordic countries have comprehensive, population-based health and medical registries linkable on individually unique personal identity codes, enabling complete long-term follow-up. The aims of this study were to describe the NorTwinCan cohort established in 2010 and assess whether the cancer mortality and incidence rates among Nordic twins are similar to those in the general population. We analyzed approximately 260,000 same-sexed twins in the nationwide twin registers in Denmark, Finland, Norway and Sweden. Cancer incidence was determined using follow-up through the national cancer registries. We estimated standardized incidence (SIR) and mortality (SMR) ratios with 95% confidence intervals (CI) across country, age, period, follow-up time, sex and zygosity. More than 30,000 malignant neoplasms have occurred among the twins through 2010. Mortality rates among twins were slightly lower than in the general population (SMR 0.96; CI 95% [0.95, 0.97]), but this depends on information about zygosity. Twins have slightly lower cancer incidence rates than the general population, with SIRs of 0.97 (95% CI [0.96, 0.99]) in men and 0.96 (95% CI [0.94, 0.97]) in women. Testicular cancer occurs more often among male twins than singletons (SIR 1.15; 95% CI [1.02, 1.30]), while cancers of the kidney (SIR 0.82; 95% CI [0.76, 0.89]), lung (SIR 0.89; 95% CI [0.85, 0.92]) and colon (SIR 0.90; 95% CI [0.87, 0.94]) occur less often in twins than in the background population. Our findings indicate that the risk of cancer among twins is so similar to the general population that cancer risk factors and estimates of heritability derived from the Nordic twin registers are generalizable to the background populations.
  • Föhr, Tiina; Waller, Katja; Viljanen, Anne; Sanchez, Riikka; Ollikainen, Miina; Rantanen, Taina; Kaprio, Jaakko; Sillanpää, Elina (2021)
    Background Epigenetic clocks are based on DNA methylation (DNAm). It has been suggested that these clocks are useable markers of biological aging and premature mortality. Because genetic factors explain variations in both epigenetic aging and mortality, this association could also be explained by shared genetic factors. We investigated the influence of genetic and lifestyle factors (smoking, alcohol consumption, physical activity, chronic diseases, body mass index) and education on the association of accelerated epigenetic aging with mortality using a longitudinal twin design. Utilizing a publicly available online tool, we calculated the epigenetic age using two epigenetic clocks, Horvath DNAmAge and DNAm GrimAge, in 413 Finnish twin sisters, aged 63-76 years, at the beginning of the 18-year mortality follow-up. Epigenetic age acceleration was calculated as the residuals from a linear regression model of epigenetic age estimated on chronological age (AA(Horvath), AA(GrimAge), respectively). Cox proportional hazard models were conducted for individuals and twin pairs. Results The results of the individual-based analyses showed an increased mortality hazard ratio (HR) of 1.31 (CI95: 1.13-1.53) per one standard deviation (SD) increase in AA(GrimAge). The results indicated no significant associations of AA(Horvath) with mortality. Pairwise mortality analyses showed an HR of 1.50 (CI95: 1.02-2.20) per 1 SD increase in AA(GrimAge). However, after adjusting for smoking, the HR attenuated substantially and was statistically non-significant (1.29; CI95: 0.84-1.99). Similarly, in multivariable adjusted models the HR (1.42-1.49) was non-significant. In AA(Horvath), the non-significant HRs were lower among monozygotic pairs in comparison to dizygotic pairs, while in AA(GrimAge) there were no systematic differences by zygosity. Further, the pairwise analysis in quartiles showed that the increased within pair difference in AA(GrimAge) was associated with a higher all-cause mortality risk. Conclusions In conclusion, the findings suggest that DNAm GrimAge is a strong predictor of mortality independent of genetic influences. Smoking, which is known to alter DNAm levels and is built into the DNAm GrimAge algorithm, attenuated the association between epigenetic aging and mortality risk.
  • Torvik, Fartein Ask; Flato, Martin; McAdams, Tom A.; Colman, Ian; Silventoinen, Karri; Stoltenberg, Camilla (2021)
    Purpose: On average, boys have lower academic achievement than girls. We investigated whether the timing of puberty is associated with academic achievement, and whether later puberty among boys contributes to the sex difference in academic achievement. Method: Examination scores at age 16 were studied among 13,477 British twins participating in the population-based Twins Early Development Study. A pubertal development scale, a height based proxy of growth spurt, and age at menarche were used as indicators of puberty. Associations between puberty, sex, and academic achievement were estimated in phenotypic mediation models and biometric twin models. Results: Earlier puberty was associated with higher academic achievement both in boys and girls. The exception was early age at menarche in girls, which associated with lower academic achievement. More than half of the sex differences in academic achievement could be linked to sex differences in pubertal development, but part of this association appeared to be rooted in prepubertal differences. The biometric twin modelling indicated that the association between puberty and academic achievement was due to shared genetic risk factors. Genetic influences on pubertal development accounted for 7%-8% of the phenotypic variation in academic achievement. Conclusions: Pubertal maturation relates to the examination scores of boys and of girls. This can give genes related to pubertal maturation an influence on outcomes in education and beyond. Sex differences in pubertal maturation can explain parts of the sex difference in academic achievement. Grading students when they are immature may not accurately measure their academic potential. (c) 2021 Society for Adolescent Health and Medicine. Published by Elsevier Inc. All rights reserved. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).
  • Korhonen, Tellervo; Sihvola, Elina; Latvala, Antti; Dick, Danielle M.; Pulkkinen, Lea; Nurnberger, John; Rose, Richard J.; Kaprio, Jaakko (2018)
    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.
  • Berntzen, Bram J.; Jukarainen, Sakari; Bogl, Leonie H.; Rissanen, Aila; Kaprio, Jaakko; Pietiläinen, Kirsi H. (2019)
    We aimed to study the eating behavioral traits that associate with body mass index (BMI) among BMI-discordant twin pairs. This cross-sectional study examined self-reported eating behaviors in 134 healthy young adult twin pairs (57 monozygotic [MZ] and 77 same-sex dizygotic [DZ]), of whom 29 MZ and 46 DZ pairs were BMI discordant (BMI difference >= 3 kg/m(2)). In both MZ and DZ BMI-discordant pairs, the heavier co-twins reported being less capable of regulating their food intake optimally than their leaner co-twins, mainly due to 'frequent overeating'. Furthermore, the heavier co-twins reported augmented 'disinhibited eating', 'binge-eating scores' and 'body dissatisfaction'. The twins agreed more frequently that the heavier co-twins (rather than the leaner co-twins) ate more food in general, and more fatty food, in particular. No significant behavioral differences emerged in BMI-concordant twin pairs. Overeating - measured by 'frequent overeating', 'disinhibited eating' and 'binge-eating score' - was the main behavioral trait associated with higher BMI, independent of genotype and shared environment.
  • Karppinen, Jari E.; Rottensteiner, Mirva; Wiklund, Petri; Hamalainen, Kaisa; Laakkonen, Eija K.; Kaprio, Jaakko; Kainulainen, Heikki; Kujala, Urho M. (2019)
    Purpose We aimed to investigate if hereditary factors, leisure-time physical activity (LTPA) and metabolic health interact with resting fat oxidation (RFO) and peak fat oxidation (PFO) during ergometer cycling. Methods We recruited 23 male monozygotic twin pairs (aged 32-37 years) and determined their RFO and PFO with indirect calorimetry for 21 and 19 twin pairs and for 43 and 41 twin individuals, respectively. Using physical activity interviews and the Baecke questionnaire, we identified 10 twin pairs as LTPA discordant for the past 3 years. Of the twin pairs, 8 pairs participated in both RFO and PFO measurements, and 2 pairs participated in either of the measurements. We quantified the participants' metabolic health with a 2-h oral glucose tolerance test. Results Fat oxidation within co-twins was correlated at rest [intraclass correlation coefficient (ICC) = 0.54, 95% confidence interval (CI) 0.15-0.78] and during exercise (ICC = 0.67, 95% CI 0.33-0.86). The LTPA-discordant pairs had no pairwise differences in RFO or PFO. In the twin individual-based analysis, PFO was positively correlated with the past 12-month LTPA (r = 0.26, p = 0.034) and the Baecke score (r = 0.40, p = 0.022) and negatively correlated with the area under the curve of insulin (r = - 0.42, p = 0.015) and glucose (r = - 0.31, p = 0.050) during the oral glucose tolerance test. Conclusions Hereditary factors were more important than LTPA for determining fat oxidation at rest and during exercise. Additionally, PFO, but not RFO, was associated with better metabolic health.
  • Dubois, Lise; Diasparra, Maikol; Bedard, Brigitte; Kaprio, Jaakko; Fontaine-Bisson, Benedicte; Tremblay, Richard; Boivin, Michel; Perusse, Daniel (2013)
  • Berg, Venla; Lummaa, Virpi; Rickard, Ian J.; Silventoinen, Karri; Kaprio, Jaakko; Jokela, Markus (2016)
    Personality has been associated with reproductive success in humans and other animals, suggesting potential evolutionary selection pressures. However, studies to date have only examined these associations on a phenotypic level, which may be inadequate in estimating evolutionary change. Using a large longitudinal twin dataset of contemporary Finns, we compared the phenotypic (breeder's equation) and genetically informed (the Robertson-Price identity) associations between lifetime reproductive success (LRS) and two personality traits-neuroticism and extraversion. Neuroticism was not associated with LRS at the phenotypic nor genetic level, while extraversion was associated with higher LRS in men both phenotypically and genetically. Compared to the univariate phenotypic analysis, the genetic analysis suggested a larger selection response of extraversion, and a selection response of neuroticism due to indirect selection. We estimated that neuroticism decreases by .05 standard deviations and extraversion increases by .11 standard deviations by one generation. Our results highlight the importance of considering genetic associations between personality and fitness and investigating several inter-related personality traits and their covariance with each other to predict responses to selection more accurately.
  • Silventoinen, Karri; Su, Jinni; Pulkkinen, Lea; Barr, Peter; Rose, Richard J.; Dick, Danielle M.; Kaprio, Jaakko (2019)
    We analyzed how the effects of genetic and environmental factors on the perceptions of family interaction change from early to late adolescence. The data were collected by postal surveys on Finnish twins (N=4808) at 12, 14 and 17years of age and analyzed using genetic twin modeling. Additive genetic factors explained a modest share of the variation in perceived relational support (a(2)=0.30 in boys and 0.18 in girls) and relational tensions (a(2)=0.13 and 0.14, respectively) at 12years of age, with the proportions becoming larger through 17years of age (a(2)=0.53 in boys and 0.49 in girls for relational support; a(2)=0.35 in boys and 0.33 in girls for relational tensions). Simultaneously, the role of environment shared by co-twins decreased. These findings suggest that the associations between perceived family interaction and other factors in adulthood should be interpreted with caution, because they partly reflect genetic background, whereas in childhood, they may provide more reliable information on parental characteristics.
  • Kärkkäinen, Sanna; Silventoinen, Karri; Svedberg, Pia; Ropponen, Annina (2020)
    Purpose Musculoskeletal diagnoses (MSD) are one of the largest diagnostic groups for disability pensions (DP). This study investigated the associations between life events and DP due to MSD, considering sociodemographic, health, and familial factors. Methods The study sample included 18,530 Finnish twins, 24-64 years old at baseline, who responded to a questionnaire in 1981 including a 21-item life event inventory. Information on DP with diagnosis codes (ICD codes: M00-M99) were obtained from the official national pension registers. Life events were divided into family- and work-related events. "Positive change in life" was analyzed separately. Cox proportional hazards models were used to calculate hazard ratios (HR) with 95% confidence intervals (CI). Results During the follow-up of 23 years, 1273 (7%) individuals were granted DP due to MSD. In discordant pair analysis, family-related events (>= 4 events) increased (HR 1.63, 95% CI 1.31, 2.03) and the absence of such events decreased (HR 0.68, 95% CI 0.48, 0.95) the risk of DP due to MSD. For work-related events (>= 3 events), the risk estimates were non-significant when controlling for familial factors. Having had a positive change in life decreased the risk of DP due to MSD (HR 0.79, 95% CI 0.65, 0.96) while controlling for familial confounding, but were non-significant in the full model controlling for various covariates (HR 0.91, 95% CI 0.75, 1.12). Conclusions The associations between life events and the risk of DP due to MSD are complex and potentially affected by familial and other confounding factors including sociodemographics and health.
  • Rissanen, Annu-Riikka S.; Jernman, Riina M.; Gissler, Mika; Nupponen, Irmeli; Nuutila, Mika E. (2019)
    Background: To investigate the trends and changes in the incidence and overall outcome of twin pregnancies in Finland, a retrospective study was conducted with emphasis on maternal complications, covering a 28-year study period. Methods: All 23,498 twin pregnancies with 46,363 live born and 633 stillborn children in Finland during 1987-2014 were included in the study. Data were collected from the national Medical Birth Register and the Care Register on Hospital Care (Finnish Institute for Health and Welfare, Finland) regarding the parturients' characteristics and incidences of several pregnancy and childbirth complications. The incidences of twin pregnancies and maternal complications during pregnancy and childbirth are the main outcome measures of the study. The results are expressed in percentages, means, medians, ranges and standard deviations (SD), when appropriate. Results: Twins comprised 1.4% of all births in Finland in 1987-2014. Parturients' mean age has remained stable, but the share of over 35 year-old parturients is increasing. The incidences of pre-eclampsia, intrahepatic cholestasis of pregnancy, gestational diabetes and postpartum haemorrhage have risen during the study period. Almost half (44.9%) of twins were born preterm, almost half via Caesarean section (47.1%), and 27.7% of twin labours were induced. Conclusions: Several pregnancy complications increased during the study period. Advanced maternal age among twin parturients has risen, enhancing the risks for developing complications in a pregnancy already of a high-risk category, and predisposing to preterm delivery. National and international guidelines are necessary to improve the overall outcome of twin pregnancies.
  • Rissanen, Annu-Riikka S; Jernman, Riina M; Gissler, Mika; Nupponen, Irmeli; Nuutila, Mika E (BioMed Central, 2019)
    Abstract Background To investigate the trends and changes in the incidence and overall outcome of twin pregnancies in Finland, a retrospective study was conducted with emphasis on maternal complications, covering a 28-year study period. Methods All 23,498 twin pregnancies with 46,363 live born and 633 stillborn children in Finland during 1987–2014 were included in the study. Data were collected from the national Medical Birth Register and the Care Register on Hospital Care (Finnish Institute for Health and Welfare, Finland) regarding the parturients’ characteristics and incidences of several pregnancy and childbirth complications. The incidences of twin pregnancies and maternal complications during pregnancy and childbirth are the main outcome measures of the study. The results are expressed in percentages, means, medians, ranges and standard deviations (SD), when appropriate. Results Twins comprised 1.4% of all births in Finland in 1987–2014. Parturients’ mean age has remained stable, but the share of over 35 year-old parturients is increasing. The incidences of pre-eclampsia, intrahepatic cholestasis of pregnancy, gestational diabetes and postpartum haemorrhage have risen during the study period. Almost half (44.9%) of twins were born preterm, almost half via Caesarean section (47.1%), and 27.7% of twin labours were induced. Conclusions Several pregnancy complications increased during the study period. Advanced maternal age among twin parturients has risen, enhancing the risks for developing complications in a pregnancy already of a high-risk category, and predisposing to preterm delivery. National and international guidelines are necessary to improve the overall outcome of twin pregnancies.
  • Heinonen, Sini; Muniandy, Maheswary; Buzkova, Jana; Mardinoglu, Adil; Rodriguez, Amaia; Fruhbeck, Gema; Hakkarainen, Antti; Lundbom, Jesper; Lundbom, Nina; Kaprio, Jaakko; Rissanen, Aila; Pietiläinen, Kirsi H. (2017)
    Low mitochondrial activity in adipose tissue is suggested to be an underlying factor in obesity and its metabolic complications. We aimed to find out whether mitochondrial measures are downregulated in obesity also in isolated adipocytes. We studied young adult monozygotic (MZ) twin pairs discordant (n = 14, intrapair difference Delta BMI ae 3 kg/m(2)) and concordant (n = 5, Delta BMI <3 kg/m(2)) for BMI, identified from ten birth cohorts of 22- to 36-year-old Finnish twins. Abdominal body fat distribution (MRI), liver fat content (magnetic resonance spectroscopy), insulin sensitivity (OGTT), high-sensitivity C-reactive protein, serum lipids and adipokines were measured. Subcutaneous abdominal adipose tissue biopsies were obtained to analyse the transcriptomics patterns of the isolated adipocytes as well as of the whole adipose tissue. Mitochondrial DNA transcript levels in adipocytes were measured by quantitative real-time PCR. Western blots of oxidative phosphorylation (OXPHOS) protein levels in adipocytes were performed in obese and lean unrelated individuals. The heavier (BMI 29.9 +/- 1.0 kg/m(2)) co-twins of the discordant twin pairs had more subcutaneous, intra-abdominal and liver fat and were more insulin resistant (p <0.01 for all measures) than the lighter (24.1 +/- 0.9 kg/m(2)) co-twins. Altogether, 2538 genes in adipocytes and 2135 in adipose tissue were significantly differentially expressed (nominal p <0.05) between the co-twins. Pathway analysis of these transcripts in both isolated adipocytes and adipose tissue revealed that the heavier co-twins displayed reduced expression of genes relating to mitochondrial pathways, a result that was replicated when analysing the pathways behind the most consistently downregulated genes in the heavier co-twins (in at least 12 out of 14 pairs). Consistently upregulated genes in adipocytes were related to inflammation. We confirmed that mitochondrial DNA transcript levels (12S RNA, 16S RNA, COX1, ND5, CYTB), expression of mitochondrial ribosomal protein transcripts and a major mitochondrial regulator PGC-1 alpha (also known as PPARGC1A) were reduced in the heavier co-twins' adipocytes (p <0.05). OXPHOS protein levels of complexes I and III in adipocytes were lower in obese than in lean individuals. Subcutaneous abdominal adipocytes in obesity show global expressional downregulation of oxidative pathways, mitochondrial transcripts and OXPHOS protein levels and upregulation of inflammatory pathways. The datasets analysed and generated during the current study are available in the figshare repository.
  • Virtanen, Suvi (Helsingfors universitet, 2016)
    Depression is a psychiatric disorder composed of several clusters of symptoms, which do not necessarily reflect common pathways of pathophysiological processes. Thus, a new conceptualization of depression has been proposed, which suggests that depression should be dissected to its key components instead of treating it as one homogeneous concept. Personality trait neuroticism is a risk factor that is consistently linked with depression. Several models have been suggested for the association between neuroticism and depression. One of them is a so-called common cause -model, which assumes that a shared etiology explains the co-occurrence of the two. Research from twin studies supports this notion, as neuroticism and depression have been found to share a large proportion of their genetic basis. However, earlier research has examined depression as a composite concept, and there are no studies to date which would have examined the shared genetic basis of specific symptoms of depression in relation with neuroticism. This study tests the common cause -model by estimating, whether the same genetic and environmental components are relevant in explaining the covariation between neuroticism and specific symptoms of depression. The data used in this study was from the Swedish Adoption/Twin Study (n = 1515, av. age = 62.0). Depression was measured with The Center for Epidemiological Studies - Depression Scale (CES-D), and separate analyses were conducted for three factors: somatic complaints, (lack of) positive affect and depressed affect. The results showed that all of the depressive symptoms shared the same genetic and environmental components when modeling the association with neuroticism, which supports the common cause -model. Over a half of the phenotypic correlation was explained by genetic influences between neuroticism and somatic complaints, as well as neuroticism and positive affect. Half of the co-variation between neuroticism and depressed affect was due to genetic influences. Findings of the current study suggest, that genetic and individual specific environmental influences are important in explaining the relationship in all of the symptoms. For future endeavors, it is suggested to search for concrete risk factors and neurobiological endophenotypes that are shared between specific symptoms and neuroticism. While the use of composite concept of depression was supported in this study, the research question has not been yet examined in molecular genetic studies. A twin model can only differentiate sources of variation, not concrete risk factors. Thus, the results presented here only apply in the context of twin modeling. Also, the robustness of the results should be tested by replicating the results among younger samples.
  • Silventoinen, Karri; Konttinen, Hanna (2020)
    Obesity has dramatically increased during the last decades and is currently one of the most serious global health problems. We present a hypothesis that obesity is a neuro-behavioral disease having a strong genetic background mediated largely by eating behavior and is sensitive to the macro-environment; we study this hypothesis from the perspective of genetic research. Genetic family and genome-wide-association studies have shown well that body mass index (BMI, kg/m(2)) is a highly heritable and polygenic trait. New genetic variation of BMI emerges after early childhood. Candidate genes of BMI notably express in brain tissue, supporting that this new variation is related to behavior. Obesogenic environments at both childhood family and societal levels reinforce the genetic susceptibility to obesity. Genetic factors have a clear influence on macro-nutrient intake and appetite-related eating behavior traits. Results on the gene-by-diet interactions in obesity are mixed, but emerging evidence suggests that eating behavior traits partly mediate the effect of genes on BMI. However, more rigorous prospective study designs controlling for measurement bias are still needed.