A multivariate twin study of the genetic association between present moment attention and subjective wellbeing.

Considerable evidence supports the role of present-moment attention, a central feature of mindfulness, in subjective wellbeing maintenance and enhancement. Yet it is not clear why such a relation exists. This study examined the genetic and environmental contributions of present-moment attention to subjective wellbeing. Consistent with the "generalist genes hypothesis" and prior evidence, we hypothesized that presence and subjective wellbeing would show a substantial genetic correlation and smaller environmental correlation. Using a large epidemiological sample of healthy 16-year-old twins in the United Kingdom (N = 1136 monozygotic (MZ) and dizygotic (DZ) twin pairs), genetic overlap was found between presence and the cognitive component of subjective wellbeing (life satisfaction), and to a lesser extent, the affective component of subjective wellbeing (operationalized as happiness). The non-shared environmental overlap between these constructs was substantial. This study provides the first evidence known to us showing that present-centered attention, a primary component of mindfulness, has both genetic and environmental overlap with subjective wellbeing. The findings have implications for understanding mechanisms by which presence is associated with positive emotions and life satisfaction, and suggest, pending additional research, that mindfulness-based interventions to enhance wellbeing may be best suited to those with a genetic propensity toward mindful presence.

A population-based twin study of the symptomatic diagnostic criteria for major depression that occur within versus outside of major depressive episodes.

BACKGROUND: Are genetic risk factors for current depressive symptoms good proxies for genetic risk factors for syndromal major depression (MD)? METHODS: In over 9000 twins from the population-based Virginia Adult Twin Study of Psychiatric and Substance Use Disorders, the occurrence of all nine DSM symptomatic criteria for MD in the last year was assessed at personal interview and then grouped by their temporal co-occurrence. The DSM criteria which occurred outside (OUT) v. inside of (IN) MD episodes were then separated. We calculated tetrachoric correlations for OUT and IN depressive criteria in monozygotic (MZ) and dizygotic (DZ) pairs and fitted univariate and bivariate ACE twin models using OpenMx. RESULTS: The mean twin correlations (±95% CIs) for IN depressive criteria were substantially higher than for OUT depressive criteria in both MZ [+0.35 (0.32-0.38) v. 0.20 (0.17-0.24)] and DZ pairs [0.20 (0.17-0.24) v. 0.10 (0.04-0.16]. The mean IN-OUT cross-correlation in MZ and DZ pairs was modest [+0.15 (0.07-0.24) and +0.07 (0.03-0.12)]. The mean heritability estimates for the nine In v. Out depressive criteria was 0.31 (0.22-0.41) and 0.15 (0.08-0.21), in MZ and DZ pairs, respectively. The mean genetic correlation between the nine IN and OUT depressive criteria was +0.07 (-0.07 to 0.21). CONCLUSIONS: Depressive criteria occurring outside depressive episodes are less heritable than those occurring within. These two ways criteria can manifest are not closely genetically related. Current depressive symptoms - most of which are occurring outside of depressive episodes - are not, for genetic studies, good proxies for MD.

A Traitlike Dimension of Subjective Memory Concern Over 30 Years Among Adult Male Twins.

Importance: Subjective memory concern has long been considered a state-related indicator of impending cognitive decline or dementia. The possibility that subjective memory concern may itself be a heritable trait is largely ignored, yet such an association would substantially confound its use in clinical or research settings. Objective: To assess the heritability and traitlike dimensions of subjective memory concern and its clinical correlates. Design, Setting, and Participants: This longitudinal twin cohort study was conducted from 1967 to 2019 among male adults with a mean (SD) age of 37.75 (2.52) years to follow-up at mean ages of 56.15 (2.72), 61.50 (2.43), and 67.35 (2.57) years (hereafter, 38, 56, 62, and 67 years, respectively) in the Vietnam Era Twin Study of Aging. The study included a national community-dwelling sample with health, education, and lifestyle characteristics comparable to a general sample of US men in this age cohort. Participants were monozygotic and dizygotic twins randomly recruited from the Vietnam Era Twin Registry. Data were analyzed from May 2021 to December 2022. Main Outcomes and Measures: Measures included subjective memory concern at 4 time points; objective memory, depressive symptoms, and anxiety at the last 3 time points; negative emotionality (trait neuroticism) at age 56 years; polygenic risk scores (PRSs) for neuroticism, depression, and Alzheimer disease; APOE genotype; and parental history of dementia. Primary outcomes were heritability and correlations between subjective memory concern and other measures. Results: The sample included 1555 male adults examined at age 38 years, 520 at age 56 years (due to late introduction of subjective memory concern questions), 1199 at age 62 years, and 1192 at age 67 years. Phenotypically, subjective memory concerns were relatively stable over time. At age 56 years, subjective memory concern had larger correlations with depressive symptoms (r, 0.32; 95% CI, 0.21 to 0.42), anxiety (r, 0.36; 95% CI, 0.18 to 0.51), and neuroticism (r, 0.34; 95% CI, 0.26 to 0.41) than with objective memory (r, -0.24; 95% CI, -0.33 to -0.13). Phenotypic results were similar at ages 62 and 67 years. A best-fitting autoregressive twin model indicated that genetic influences on subjective memory concern accumulated and persisted over time (h2 = 0.26-0.34 from age 38-67 years). At age 56 years, genetic influences for subjective memory concern were moderately correlated with genetic influences for anxiety (r, 0.36; 95% CI, 0.18 to 0.51), negative emotionality (r, 0.51; 95% CI, 0.44-0.57), and depressive symptoms (r, 0.20; 95% CI, 0.10 to 0.29) as well as objective memory (r, -0.22; 95% CI, -0.30 to -0.14). Similar genetic correlations were seen at ages 62 and 67 years. The neuroticism PRS was associated with subjective memory concern at age 38 years (r, 0.10; 95% CI, 0.03. to 0.18) and age 67 years (r, 0.09; 95% CI, 0.01 to 0.16). Subjective memory concern was not associated with any Alzheimer disease risk measures. Conclusions and Relevance: This cohort study found stable genetic influences underlying subjective memory concern dating back to age 38 years. Subjective memory concern had larger correlations with affect-related measures than with memory-related measures. Improving the utility of subjective memory concern as an indicator of impending cognitive decline and dementia may depend on isolating its statelike component from its traitlike component.

Associations Between General and Specific Psychopathology Factors and 10-Year Clinically Relevant Outcomes in Adult Swedish Twins and Siblings.

Importance: General and specific factors of psychopathology are associated with future adverse outcomes, indicating that they might be useful for identifying individuals at greatest risk. However, it remains unknown if these associations are attributable to confounders that may influence both the psychopathology factors and later outcomes. Objective: To analyze associations between psychopathology factors and clinically relevant outcomes within family pairs, adjusting for unmeasured confounds by applying co-twin control and sibling comparison designs. Design, Setting, and Participants: This longitudinal cohort study with a follow-up range of 9 to 13 years included all Swedish twins born from 1959 to 1985 who participated in the Study of Twin Adults: Genes and Environment (60% response rate) and the oldest pair of all Swedish siblings born from 1959 to 1985 per the Multi-Generation Register. Twins were evaluated based on responses to a hierarchical factor model derived using multivariate statistics. Sibling pairs were evaluated based on psychiatric diagnoses per the Swedish National Patient Register. Information on outcome events and prescriptions were derived from the National Patient Register, Prescribed Drug Register, and Crime Register. Baseline assessment was in August 2005, and data were analyzed from January 2022 to February 2023. Exposures: Hierarchical factor model consisting of 1 general and 4 specific factors fit to 48 psychiatric symptoms on which twin participants self-reported in 2005 and 1 general and 3 specific factors fit to 9 register-based psychiatric diagnoses assigned to sibling participants prior to 2005. Main Outcomes and Measures: Outcomes consisted of 7 register-based events occurring after 2005, including suicidal behavior, substance overdoses, and criminal suspicion or convictions (data available until the end of 2013), and prescription of antidepressants, antialcohol or antiopioid medication, antipsychotics, and stimulants (data available until the end of 2017). Results: The study included 32 328 twins (mean [SD] age, 34 [8] years; 16 076 [49.73%] male) and 1 942 106 siblings (mean [SD] age, 34 [7] years; 991 500 [51.05%] male). General psychopathology was significantly associated with all 7 outcomes within sibling pairs (mean within-pair odds ratio [OR], 2.28; 95% CI, 2.19-2.37) and dizygotic twin pairs (within-pairs OR, 1.65; 95% CI, 1.38-1.98) and with 3 outcomes within monozygotic twin pairs (mean within-pairs OR, 1.77; 95% CI, 1.35-2.36). Within sibling pairs, the specific internalizing factor was associated with antidepressant prescriptions (within-pairs OR, 1.65; 95% CI, 1.59-1.71), the specific substance misuse factor was associated prescription of antialcohol and antiopioid medication (within-pairs OR, 2.36; 95% CI, 2.20-2.54), and the specific psychotic factor was associated with antipsychotic medications (within-pairs OR, 1.61; 95% CI, 1.51-1.72). Similar results emerged within twin pairs. Conclusion and Relevance: In this cohort study, general psychopathology was significantly associated with all 7 outcomes within sibling and dizygotic twin pairs and 3 outcomes within monozygotic twin pairs at 10 years. Within twin and sibling pairs, the specific factors were primarily associated with related outcomes. Several of the associations in this cohort study could not be attributed to unmeasured confounds shared by family members, suggesting that interventions toward broad psychopathology dimensions might help reduce the risk of future clinically relevant events.

Heritability of overlapping impulsivity and compulsivity dimensional phenotypes.

Impulsivity and compulsivity are traits relevant to a range of mental health problems and have traditionally been conceptualised as distinct constructs. Here, we reconceptualised impulsivity and compulsivity as partially overlapping phenotypes using a bifactor modelling approach and estimated heritability for their shared and unique phenotypic variance within a classical twin design. Adult twin pairs (N = 173) completed self-report questionnaires measuring psychological processes related to impulsivity and compulsivity. We fitted variance components models to three uncorrelated phenotypic dimensions: a general impulsive-compulsive dimension; and two narrower phenotypes related to impulsivity and obsessiveness.There was evidence of moderate heritability for impulsivity (A2 = 0.33), modest additive genetic or common environmental effects for obsessiveness (A2 = 0.25; C2 = 0.23), and moderate effects of common environment (C2 = 0.36) for the general dimension, This general impulsive-compulsive phenotype may reflect a quantitative liability to related mental health disorders that indexes exposure to potentially modifiable environmental risk factors.

Psychometric and Classification Properties of the Peas in a Pod Questionnaire.

We examined the item properties of the Two Peas Questionnaire (TPQ) among a sample of same-sex twin pairs from the Washington State Twin Registry. With the exception of the 'two peas' item, three of the mistakenness items showed differential item functioning. Results showed that the monozygotic (MZ) and dizygotic (DZ) pairs may differ in their responses on these items, even among those with similar latent traits of similarity and confusability. Upon comparing three classification methods to determine the zygosity of same-sex twins, the overall classification accuracy rate was over 90% using the unit-weighted pair zygosity sum score, providing an efficient and sufficiently accurate zygosity classification. Given the inherent nature of twin-pair similarity, the TPQ is more accurate in the identification of MZ than DZ pairs. We conclude that the TPQ is a generally accurate, but by no means infallible, method of determining zygosity in twins who have not been genotyped.

[Heritability of alcohol intake among adult twins, calculate by the structural equation model].

Objective: To explore the genetic and environmental effects on alcohol intake. Methods: Data on 9 231 pairs of adult twins of the same sex was collected from the Chinese National Twin Registry (CNTR), between 2015 and 2018 and used in this study. Structural equation model was used to estimate the effects of genetic and environmental factors on alcohol intake. Results: A total of 9 231 pairs of twins were included in the analysis, of which 6 085 pairs were monozygotic (MZ). The average age of MZ was (36.91±13.07) years old, and males accounted for 56.80%. The average age of dizygotic twins (DZ) was (35.22±12.48) years old, and males accounted for 55.91%. There were 350 pairs of alcohol-drinking twins were with high-risk, accounting for 1.90% and another 367 pairs (1.99%) were with medium-risk. Alcohol-drinkers with medium-risk were affected by additive genetics, common and unique environmental factors, seen among the twins. The overall heritability appeared as 24.3% (95%CI: 0 to 56.8%). Furthermore, 50.7% of the variation (95%CI: 20.4%-79.0%) could be explained by the common environmental factors and 24.9% (95%CI: 18.3%-36.5%) by unique environmental factors. High-risk related drinking behavior was affected by both common and unique environmental factors. The common environmental component appeared as 75.6% (95%CI: 69.6%-80.8%) and unique environmental component as 24.4% (95%CI: 19.2%-30.4%), respectively. Gender difference was seen in the heritability of those with medium or high-risk drinking behaviors. The heritability of men was 30.8% (95%CI: 9.8%-53.5%), while in women it was mainly affected by the environment. Conclusion: Both alcohol drinkers with medium and high-risk drinking behaviors were mainly affected by the environment factors and gender. With the increase of drinking volume, the effect of environment on drinking behaviors became more obvious.

Neighborhood Deprivation Moderates Shared and Unique Environmental Influences on Hazardous Drinking: Findings from a Cross-Sectional Co-Twin Study.

Background: There has been increased interest in the interplay of genetic and environmental factors in the development of problematic alcohol use, including socioeconomic conditions of the neighborhood. Using a co-twin design, we examined the extent to which contributions of genetic, shared environmental, and unique environmental influences on hazardous drinking differed according to levels of neighborhood socioeconomic deprivation. Method: Data came from 1,521 monozygotic (MZ) and 609 dizygotic (DZ) twin pairs surveyed in Washington State. A measure of neighborhood deprivation was created based on census-tract-level variables and the Alcohol Use Disorders Identification Test 3-item instrument was used to assess level of hazardous drinking. We tested a series of nested structural equation models to examine associations among hazardous drinking, neighborhood deprivation, and the variance components (genetic [A], shared [C] and unique environmental [E] influences) of these two constructs, testing for both main effects and moderation by neighborhood deprivation. Results: Neighborhood deprivation was significantly associated with increased hazardous drinking, after accounting for A and C variance common to both phenotypes. Adjusting for within-pair differences in income and education, neighborhood deprivation moderated the magnitude of variance components of hazardous drinking, with the variance attributable to shared environment and non-shared environment increasing in more deprived neighborhoods. Conclusions: Findings point to amplification of early childhood as well as unique adulthood environmental risk on hazardous drinking in areas of greater deprivation.

A Twin Study of Inhibitory Control at Age Two and ADHD Behavior Problems at Age Three.

Low levels of childhood inhibitory control (IC) are phenotypically and genetically associated with externalizing behavior problems and attention deficit hyperactivity disorder (ADHD). Unfortunately, there is little research on this topic in early childhood, when IC first emerges. This investigation extends the previous findings of contemporaneous genetic covariance between parent-rated and laboratory-assessed IC and ADHD at age 2 by examining longitudinal links between IC at age two and ADHD behavior problems at age three in a sample of 314 same-sex twin pairs (145 monozygotic or MZ, 169 dizygotic or DZ). There were significant phenotypic associations between both parent and laboratory IC assessments at age two and later ADHD behavioral problems (correlations ranged from - .15 to - .44). In our model-fitting strategy, we included measures of ADHD and IC at age 2 as predictors of ADHD at age 3. Longitudinal genetic analyses showed that phenotypic covariance between age two IC and ADHD behavior problems one year later were explained by overlapping genetic variance (genetic correlations ranged from - .28 to - .60). However, these effects were not unique to IC and reflect variance shared with ADHD at age 2. Parent-rated IC at age two showed higher phenotypic and genetic covariance with ADHD at age three than lab ratings of IC at age two. This is the first investigation examining genetic covariance between parent and lab-based IC at age two and ADHD behavior problems at age three. Findings show that after accounting for co-occurring ADHD, early temperamental IC is not a unique genetic risk factor for later ADHD.

Phenotypic and aetiological architecture of depressive symptoms in a Japanese twin sample.

BACKGROUND: The phenotypic and aetiological architecture of depression symptomatology has been mostly studied in Western samples. In this study, we conducted a genetically informed factor analysis to elucidate both the phenotypic and aetiological architectures of self-reported depression among a Japanese adult twin sample. METHODS: Depressive symptoms assessed by Zung's Self-rating Depression Scale were self-rated by 425 twin pairs (301 monozygotic and 124 dizygotic twin pairs) in a community sample in Japan. RESULTS: An exploratory factor analysis extracted three symptom domains representing cognitive, affective and somatic symptomatology. A confirmatory factor analysis demonstrated that a bi-factor solution fitted better than the alternative solutions, implying that depression may be defined as a combination of a single general construct and three factors specific to each of the three symptom domains. A multivariate genetic analysis with the bi-factor solution showed that the general factor was substantially heritable (47%), and that only the affective symptom domain was significantly heritable (29%) among the three specific factors, their remaining variance being explained by non-shared environmental influences. CONCLUSIONS: Depression symptomatology appears to be adequately captured by a substantially heritable general factor. The heritability of this factor (47%) in a Japanese adult sample is in line with commonly reported heritability estimates for depression. The three specific factors - cognitive, affective and somatic - are mostly explained by non-shared environmental factors, which include measurement error. The extent to which these specific factors are uniquely associated with correlates of depression when the general factor is accounted for should be investigated in future studies.

Midlife Study of the Louisville Twins: Connecting Cognitive Development to Biological and Cognitive Aging.

The Louisville Twin Study (LTS) began in 1958 and became a premier longitudinal twin study of cognitive development. The LTS continuously collected data from twins through 2000 after which the study closed indefinitely due to lack of funding. Now that the majority of the sample is age 40 or older (61.36%, N = 1770), the LTS childhood data can be linked to midlife cognitive functioning, among other physical, biological, social, and psychiatric outcomes. We report results from two pilot studies in anticipation of beginning the midlife phase of the LTS. The first pilot study was a participant tracking study, in which we showed that approximately 90% of the Louisville families randomly sampled (N = 203) for the study could be found. The second pilot study consisted of 40 in-person interviews in which twins completed cognitive, memory, biometric, and functional ability measures. The main purpose of the second study was to correlate midlife measures of cognitive functioning to a measure of biological age, which is an alternative index to chronological age that quantifies age as a function of the breakdown of structural and functional physiological systems, and then to relate both of these measures to twins' cognitive developmental trajectories. Midlife IQ was uncorrelated with biological age (- .01) while better scores on episodic memory more strongly correlated with lower biological age (- .19 to - .31). As expected, midlife IQ positively correlated with IQ measures collected throughout childhood and adolescence. Additionally, positive linear rates of change in FSIQ scores in childhood significantly correlated with biological age (- .68), physical functioning (.71), and functional ability (- .55), suggesting that cognitive development predicts lower biological age, better physical functioning, and better functional ability. In sum, the Louisville twins can be relocated to investigate whether and how early and midlife cognitive and physical health factors contribute to cognitive aging.

The South Korean Twin Registry.

The South Korean Twin Registry (SKTR) is an ongoing nationwide volunteer registry of South Korean twins and their families. Since its inception, from preschooler to young adult, twins have been registered with the SKTR and have demonstrated that relative influences of genetic and environmental factors explaining individual differences in various psychological, mental health and physical traits in South Koreans are similar to those found in many Western twin studies. Currently, studies at the SKTR focus on identification of the process of gene-by-environment interactions as well as developmental differences in genetic and environmental influences on psychological and mental health traits in South Koreans. This report provides a brief overview, recruitment strategies, current samples, zygosity assessment, measures and future directions of the SKTR.

Identifying subtypes of cannabis users based on simultaneous polysubstance use.

BACKGROUND: Cannabis use patterns vary considerably, with many users reporting simultaneous and non-simultaneous use (co-use) of other substances. Despite this, little research has examined the extent to which subtypes of cannabis users may be identified based on their simultaneous and co-use behaviors. METHODS: The sample consisted of adult Australian twins and siblings who reported lifetime cannabis use (n = 2590). A latent class analysis was conducted to determine subtypes of cannabis users based on five indicators of substance co-use and simultaneous use. Adolescent correlates (age of substance initiation and conduct disorder) and adult correlates (substance use/disorder and depression) of class membership were assessed. Twin similarity for class membership was also examined. RESULTS: Four subtypes of users were identified: 1) alcohol co-users, 2) simultaneous alcohol users, 3) simultaneous tobacco users, and 4) simultaneous alcohol, tobacco, and drug users. Compared to co-users of alcohol, simultaneous alcohol users were at increased risk for alcohol problems. Patterns of use that involved simultaneous tobacco and cannabis use (i.e., simultaneous tobacco users and simultaneous alcohol, tobacco, and drug users) were associated with the most problematic outcomes, including substance use and disorder. There was evidence for genetic influences (12-58%) on cannabis use patterns, with higher concordance for latent class membership among monozygotic compared to dizygotic twins (χ2 (1) = 7.19, p = 0.007). CONCLUSIONS: The current study identified four classes of cannabis users at varying degrees of risk. Results suggest that simultaneous tobacco and cannabis use may be especially associated with deleterious outcomes.

The Quebec Newborn Twin Study at 21.

This paper is a revised and updated edition of a previous description of the Quebec Newborn Twin Study (QNTS), an ongoing prospective longitudinal follow-up of a birth cohort of twins born between 1995 and 1998 in the greater Montreal area, Québec, Canada. The goal of QNTS is to document individual differences in the cognitive, behavioral, and social-emotional aspects of developmental health across childhood, their early genetic and environmental determinants, as well as their putative role in later social-emotional adjustment, school, health, and occupational outcomes. A total of 662 families of twins were initially assessed when the twins were aged 6 months. These twins and their family were then followed regularly. QNTS now has 16 waves of data collected or planned, including 5 in preschool. Over the last 24 years, a broad range of physiological, cognitive, behavioral, school, and health phenotypes were documented longitudinally through multi-informant and multimethod measurements. QNTS also entails extended and detailed multilevel assessments of proximal (e.g., parenting behaviors, peer relationships) and distal (e.g., family income) features of the child's environment. QNTS children and a subset of their parents have been genotyped, allowing for the computation of a variety of polygenic scores. This detailed longitudinal information makes QNTS uniquely suited for the study of the role of the early years and gene-environment transactions in development.

Twins Early Development Study: A Genetically Sensitive Investigation into Behavioral and Cognitive Development from Infancy to Emerging Adulthood.

The Twins Early Development Study (TEDS) is a longitudinal twin study that recruited over 16,000 twin-pairs born between 1994 and 1996 in England and Wales through national birth records. More than 10,000 of these families are still engaged in the study. TEDS was and still is a representative sample of the population in England and Wales. Rich cognitive and emotional/behavioral data have been collected from the twins from infancy to emerging adulthood, with data collection at first contact and at ages 2, 3, 4, 7, 8, 9, 10, 12, 14, 16, 18 and 21, enabling longitudinal genetically sensitive analyses. Data have been collected from the twins themselves, from their parents and teachers, and from the UK National Pupil Database. Genotyped DNA data are available for 10,346 individuals (who are unrelated except for 3320 dizygotic co-twins). TEDS data have contributed to over 400 scientific papers involving more than 140 researchers in 50 research institutions. TEDS offers an outstanding resource for investigating cognitive and behavioral development across childhood and early adulthood and actively fosters scientific collaborations.

The Study of Personality Architecture and Dynamics (SPeADy): A Longitudinal and Extended Twin Family Study.

The Study of Personality Architecture and Dynamics (SPeADy) is a German research project that aims to investigate the sources of interindividual differences in intraindividual personality development. The main focus lies in the dynamic interplay between more stable core characteristics and more environmentally malleable surface characteristics, as well as between personality and life experiences over time. SPeADy includes a twin family study encompassing data from 1962 individuals (age: 14-94) of 682 families, including 570 complete twin pairs (plus 1 triplet set), 327 parents, 236 spouses and 145 children of twins. Data collection started in 2016 and data from the first wave are currently obtainable as open source. Available data comprise a broad range of personality variables, such as personality trait constructs, motives, interests, values, moral foundations, religiosity and self-related concepts. For the currently ongoing second wave of data collection, we added retrospective reports on major life events. Special features of this genetically informative study are the extended twin family data and its longitudinal design. Three assessment waves in 2 years' intervals are planned until 2022. In this article, we briefly describe the design and contents of the SPeADy twin family study as well as some recent findings, future plans and open science issues.

The Beijing Twin Study (BeTwiSt): An Update.

The Beijing Twin Study (BeTwiSt), which was established in 2006, is an ongoing study aiming to investigate the genetic and environmental etiology of adolescent psychopathology. Resting-state brain imaging datasets have been examined for same-sex twins, and other psychological traits and emotional and behavioral variables have been examined for all twins. Based on the registry, the main findings regarding the etiological mechanism underlying adolescent development, magnetic resonance imaging results, and genetic and environmental influences on other psychological traits have been published. This article summarizes the key findings in these three areas and discusses future plans for the BeTwiSt.

Inheritance of Neural Substrates for Motivation and Pleasure.

Despite advances in the understanding of the reward system and the role of dopamine in recent decades, the heritability of the underlying neural mechanisms is not known. In the present study, we examined the hemodynamic activation of the nucleus accumbens (NAcc), a key hub of the reward system, in 86 healthy monozygotic twins and 88 healthy dizygotic twins during a monetary-incentive-delay task. The participants also completed self-report measures of pleasure. Using voxelwise heritability mapping, we found that activation of the bilateral NAcc during the anticipation of monetary gains had significant heritability (h2 = .20-.49). Moreover, significant shared genetic covariance was observed between pleasure and NAcc activation during the anticipation of monetary gain. These findings suggest that both NAcc activation and self-reported pleasure may be heritable and that their phenotypic correlation may be partially explained by shared genetic variation.

Adolescents self-reported sleep quality and emotional regulation: a discordant twin study.

AIM: This study explores the association between sleep quality and emotional regulation, and investigates the genetic and environmental bases of this association. METHODS: Three-hundred-eighty-two adolescent twins, from the Italian Twin Registry, and their parents filled the Youth Self-Report and Child Behavior Checklist questionnaires, from which the construct of Effortful Control (EC) was derived as a measure of emotional regulation. Twins were identified as "good" or "non-good" sleepers based on answers to the Sleep Disorders Questionnaire. EC levels were compared between same-sex sleep discordant twins. RESULTS: A significant association was detected between EC scores and sleep quality. When controlling for shared (fetal or early life) environmental factors and genetic background in the discordant twin analysis, this association weakened in dizygotic twins and disappeared in monozygotic twins. CONCLUSION: Results support the association between sleep quality and EC in adolescence; furthermore, they suggest that sleep quality and emotional regulation may depend on common genetic or environmental factors.

The University of São Paulo Twin Panel: Current Status and Prospects for Brazilian Twin Studies in Behavioral Research.

The University of São Paulo Twin Panel (Painel USP de Gêmeos), based at the Institute of Psychology of the University of São Paulo, started formally in 2017. Our registry is new, but in only two years of formal existence, it comprises a volunteer sample of 4826 registered individuals (98% twins and 2% higher-order multiples), recruited at the University of São Paulo and by social media campaigns. Our main aim is to conduct and promote research with twins on psychological processes and behavior. The University of São Paulo is the largest higher education and research institution in South America, and the Painel USP de Gêmeos has great potential for fostering research on twin-related issues from a psychological perspective in Brazil and South America.