The association between aberrant salience and psychotic experiences in general population twins, and genetic vulnerability as a modifier.

BACKGROUND: Previous studies assessing the hypothesis that the construct of 'aberrant salience' is associated with psychosis and psychotic symptoms showed conflicting results. For this reason, the association between measures to index aberrant salience and subclinical psychotic symptoms in a general population sample was analysed. In addition, genetic vulnerability was added to the analysis as a modifier to test the hypothesis that modification by genetic vulnerability may explain variability in the results. METHODS: The TwinssCan project obtained data from general population twins (N = 887). CAPE (Community Assessment of Psychic Experience) scores were used to index psychotic experiences. Aberrant salience was assessed with white noise task and ambiguous situations task. RESULTS: Measures of aberrant salience were not associated with psychotic experiences, nor was there evidence for an interaction with genetic predisposition in this association (Z = 1.08, p = 0.282). CONCLUSIONS: Various studies including the present could not replicate the association between aberrant salience and psychotic experiences in general population samples. The conflicting findings might be explained by moderation by genetic vulnerability, but results are inconsistent. If there was evidence for a main effect or interaction, this was in the positive symptom scale only. On the other hand, the association was more robust in so-called 'ultra-high risk' patients and first episode psychosis patients. Thus, this association may represent a state-dependent association, present only at the more severe end of the psychosis spectrum.

Age at separation, residential mobility, and depressive symptoms among twins in late adolescence and young adulthood: a FinnTwin12 cohort study.

BACKGROUND: Separating with close siblings and leaving the parental home at an early age represents a major life event for an adolescent (reflected by age at separation in a twin pair) and may predispose them to poor mental health. This study aims to examine the association of age at separation and residential mobility on depressive symptoms in late adolescence and young adulthood and to explore possible underlying genetic effects. METHODS: Residential mobility consisted of the number and total distance of moves before age 17. Based on 3071 twins from the FinnTwin12 cohort, we used linear regression to assess the association of age at separation and residential mobility with General Behavior Inventory (GBI) scores at age 17 and in young adulthood. A higher GBI score indicated more depressive symptoms occurred. Then, the mixed model for repeated measures (MMRM) was used to visualize the scores' trajectory and test the associations, controlling for "baseline" state. Twin analyses with a bivariate cross-lagged path model were performed between the difference in GBI scores, between cotwins, and separation status for the potential genetic influence. RESULTS: Compared to twins separated before age 17, twins who separated later had significantly lower GBI scores at age 17 and in young adulthood. In MMRM, separation at a later age and a higher number of moves were associated with a higher GBI score in young adulthood. A small genetic effect was detected wherein GBI within-pair differences at age 17 were associated with separation status before age 22 (coefficient: 0.01). CONCLUSION: The study provides valid evidence about the influence of siblings and family on depressive symptoms in later adolescence and young adulthood while finding some evidence for a reverse direction effect. This suggests more caution in the interpretation of results. A strong association between residential mobility and depressive symptoms was affirmed, although further detailed research is needed.

The effect of perceived social support on fatigue in mothers having twin infants: the mediating role of sleep quality.

The aim of this study is to investigate the mediating role of sleep quality in the relationship between multidimensional perceived social support and fatigue among mothers of twin infants. One hundred and six (106) twin mothers participated in this cross-sectional study, who completed the Descriptive Information Form, Multidimensional Scale of Perceived Social Support, Pittsburgh Sleep Quality Index, and Checklist Individual Strength. The scale score averages of the mothers in the study are as follows: social support, 61.41 ± 23.86; fatigue, 77.64 ± 28.68; and sleep quality, 8.26 ± 2.38. According to the path model, perceived social support has a negative effect on poor sleep quality (p = .001, Beta = -0.411), and poor sleep quality has a positive effect on fatigue (p = .001, Beta = 0.335). Sleep quality also mediates the effect of multidimensional perceived social support on mothers' fatigue levels (p = .001, Beta = -0.138). The study results suggest that the perceived social support and fatigue levels of twin mothers are moderate, while their sleep quality is poor. Therefore, mothers of twin infants may benefit from increased social support to alleviate fatigue and enhance sleep quality.

Overlapping genetic influences between creativity and borderline personality symptoms in a large Dutch sample.

Creativity and mental disorders are sometimes seen as intertwined, but research is still unclear on whether, how much, and why. Here we explore the potential role of shared genetic factors behind creativity and symptoms of borderline personality disorder (BPD, characterized by mood swings and randomness of thoughts). Data were collected from 6745 twins (2378 complete pairs) by the Netherlands Twin Register on BPD scores (PAI-BOR questionnaire) and working in a creative profession (proxy for creativity). First, we tested whether there is an association between BPD symptoms and creative professions. Results confirmed that individuals scoring higher on the BPD spectrum are more likely to have a creative profession (Cohen's d = 0.16). Next, we modeled how much of this association reflects underlying genetic and/or environmental correlations-by using a bivariate classical twin design. We found that creativity and BPD were each influenced by genetic factors (heritability = 0.45 for BPD and 0.67 for creativity) and that these traits are genetically correlated rG = 0.17. Environmental influences were not correlated. This is evidence for a common genetic mechanism between borderline personality scores and creativity which may reflect causal effects and shed light on mechanisms.

A qualitative investigation of experiences of breastfeeding twins and multiples.

BACKGROUND: Research has found that twins and multiples are less likely to be breastfed than singleton babies. Exploration of the experience of breastfeeding twins and multiples from parents' perspectives is limited, and we know little about the experiences of those who breastfeed twins and multiples and the possible barriers they face. AIM: The aim of the research was to explore experiences of breastfeeding twins and multiples in the UK from the perspective of birthing parents. METHODS: A qualitative online survey was carried out (n = 94), followed by online semi-structured interviews (n = 18). The data were analysed using reflexive thematic analysis. FINDINGS: Four themes were developed from the data: (1) "It's one of the things I'm most proud of in my life" (2) The importance of support: "it definitely takes a village with twins" (3) Barriers and the pressure to formula feed: "all they wanted to do was stuff 'em full of formula" and (4) The dynamic experience of breastfeeding twins. DISCUSSION: Many of the participants were able to feed their babies in part due to sheer determination and the refusal to give up when met with challenges. Breastfeeding was an important part of their identity as a mother, however mental health was often impacted by their experiences, as well as the challenges they faced when seeking support. CONCLUSION: Breastfeeding twins and multiples is a challenging yet rewarding experience. Our findings indicate that further training and support is needed to enable healthcare providers to support parents of twins on their breastfeeding journey.

Testing Quantitative and Qualitative Sex Effects in a National Swedish Twin-Sibling Study of Posttraumatic Stress Disorder.

OBJECTIVE: Twin studies have demonstrated that posttraumatic stress disorder (PTSD) is moderately heritable, and the pattern of findings across studies suggests higher heritability in females compared with males. Formal testing of sex differences has yet to be done in twin studies of PTSD. The authors sought to estimate the genetic and environmental contributions to PTSD, and to formally test for sex differences, in the largest sample to date of both sexes, among twins and siblings. METHODS: Using the Swedish National Registries, the authors performed structural equation modeling to decompose genetic and environmental variance for PTSD and to formally test for quantitative and qualitative sex differences in twins (16,242 pairs) and in full siblings within 2 years of age of each other (376,093 pairs), using diagnostic codes from medical registries. RESULTS: The best-fit model suggested that additive genetic and unique environmental effects contributed to PTSD. Evidence for a quantitative sex effect was found, such that heritability was significantly greater in females (35.4%) than males (28.6%). Evidence of a qualitative sex effect was found, such that the genetic correlation was high but less than complete (rg=0.81, 95% CI=0.73-0.89). No evidence of shared environment or special twin environment was found. CONCLUSIONS: This is the first demonstration of quantitative and qualitative sex effects for PTSD. The results suggest that unique environmental effects, but not the shared environment, contributed to PTSD and that genetic influences for the disorder are stronger in females compared with males. Although the heritability is highly correlated, it is not at unity between the sexes.

Evidence for strong genetic correlations among internalizing psychopathology and related self-reported measures using both genomic and twin/adoptive approaches.

The internalizing construct captures shared variance underlying risk for mood and anxiety disorders. Internalizing factors based on diagnoses (or symptoms) of major depressive disorder (MDD) and generalized anxiety disorder (GAD) are well established. Studies have also integrated self-reported measures of associated traits (e.g., questionnaires assessing neuroticism, worry, and rumination) onto these factors, despite having not tested the assumption that these measures truly capture the same sets of risk factors. This study examined the overlap among both sets of measures using converging approaches. First, using genomic structural equation modeling, we constructed internalizing factors based on genome-wide association studies (GWASs) of internalizing diagnoses (e.g., MDD) and traits associated with internalizing (neuroticism, loneliness, and reverse-scored subjective well-being). Results indicated the two factors were highly (rg = .79) but not perfectly genetically correlated (rg < 1.0, p < .001). Second, we constructed similar latent factors in a combined twin/adoption sample of adults from the Colorado Adoption/Twin Study of Lifespan Behavioral Development and Cognitive Aging. Again, both factors demonstrated strong overlap at the level of genetic (rg = .76, 95% confidence interval [CI] [0.40, 0.97]) and nonshared environmental influences (re = .80, 95% CI [0.53, 1.0]). Shared environmental influences were estimated near zero for both factors. Our findings are consistent with current frameworks of psychopathology, though they suggest there are some unique genetic influences captured by internalizing diagnosis compared to trait measures, with potentially more nonadditive genetic influences on trait measures. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Attachment and Political Personality are Heritable and Distinct Systems, and Both Share Genetics with Interpersonal Trust and Altruism.

The attachment and caregiving domains maintain proximity and care-giving behavior between parents and offspring, in a way that has been argued to shape people's mental models of how relationships work, resulting in secure, anxious or avoidant interpersonal styles in adulthood. Several theorists have suggested that the attachment system is closely connected to orientations and behaviors in social and political domains, which should be grounded in the same set of familial experiences as are the different attachment styles. We use a sample of Norwegian twins (N = 1987) to assess the genetic and environmental relationship between attachment, trust, altruism, right-wing authoritarianism (RWA), and social dominance orientation (SDO). Results indicate no shared environmental overlap between attachment and ideology, nor even between the attachment styles or between the ideological traits, challenging conventional wisdom in developmental, social, and political psychology. Rather, evidence supports two functionally distinct systems, one for navigating intimate relationships (attachment) and one for navigating social hierarchies (RWA/SDO), with genetic overlap between traits within each system, and two distinct genetic linkages to trust and altruism. This is counter-posed to theoretical perspectives that link attachment, ideology, and interpersonal orientations through early relational experiences.

Assessing structural models of neighborhood and family sociodemographic characteristics and their relations with externalizing psychopathology.

Externalizing psychopathology has been found to have small to moderate associations with neighborhood and family sociodemographic characteristics. However, prior studies may have used suboptimal operationalizations of neighborhood sociodemographic characteristics and externalizing psychopathology, potentially misestimating relations between these constructs. To address these limitations, in the current study we test different measurement models of these constructs and assess the structural relations between them. Using a population-representative sample of 2,195 twins and siblings from the Georgia Twin Study and data from the National Neighborhood Data Archive and 2000 U.S. Census, we assessed the fit of competing measurement models for family sociodemographic, neighborhood sociodemographic, and neighborhood environment characteristics. In structural models, we regressed a general externalizing dimension on different operationalizations of these variables separately and then simultaneously in a final model. Latent variable operationalizations of family sociodemographic, neighborhood sociodemographic, and neighborhood environment characteristics explained no more variance in broad externalizing psychopathology than other operationalizations. In an omnibus model, family sociodemographic characteristics showed a small association with externalizing psychopathology, while neighborhood sociodemographic and environmental characteristics did not. Family sociodemographic characteristics showed small associations with neighborhood sociodemographic and environmental characteristics, and neighborhood sociodemographic characteristics were moderately associated with neighborhood environment. These findings suggest that family sociodemographic characteristics are more associated with the development of broad externalizing psychopathology in youth than neighborhood sociodemographic characteristics and neighborhood environment. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Adolescents' Perceptions of Household Chaos Predict Their Adult Mental Health: A Twin-Difference Longitudinal Cohort Study.

This study tested whether adolescents who perceived less household chaos in their family's home than their same-aged, same-sex sibling achieved more favorable developmental outcomes in young adulthood, independent of parent-reported household chaos and family-level confounding. Data came from 4,732 families from the Twins Early Development Study, a longitudinal, U.K.-population representative cohort study of families with twins born in 1994 through 1996 in England and Wales. Adolescents who reported experiencing greater household chaos than their sibling at the age of 16 years suffered significantly poorer mental-health outcomes at the age of 23 years, independent of family-level confounding. Mental-health predictions from perceived household chaos at earlier ages were not significant, and neither were predictions for other developmental outcomes in young adulthood, including socioeconomic status indicators, sexual risk taking, cannabis use, and conflict with the law. The findings suggest that altering children's subjective perceptions of their rearing environments may help improve their adult mental health.

Genetics of environmental sensitivity and its association with variations in emotional problems, autistic traits, and wellbeing.

Greater environmental sensitivity has been associated with increased risk of mental health problems, especially in response to stressors, and lower levels of subjective wellbeing. Conversely, sensitivity also correlates with lower risk of emotional problems in the absence of adversity, and in response to positive environmental influences. Additionally, sensitivity has been found to correlate positively with autistic traits. Individual differences in environmental sensitivity are partly heritable, but it is unknown to what extent the aetiological factors underlying sensitivity overlap with those on emotional problems (anxiety and depressive symptoms), autistic traits and wellbeing. The current study used multivariate twin models and data on sensitivity, emotional problems, autistic traits, and several indices of psychological and subjective wellbeing, from over 2800 adolescent twins in England and Wales. We found that greater overall sensitivity correlated with greater emotional problems, autistic traits, and lower subjective wellbeing. A similar pattern of correlations was found for the Excitation and Sensory factors of sensitivity, but, in contrast, the Aesthetic factor was positively correlated with psychological wellbeing, though not with emotional problems nor autistic traits. The observed correlations were largely due to overlapping genetic influences. Importantly, genetic influences underlying sensitivity explained between 2 and 12% of the variations in emotional problems, autistic traits, and subjective wellbeing, independent of trait-specific or overlapping genetic influences. These findings encourage incorporating the genetics of environmental sensitivity in future genomic studies aiming to delineate the heterogeneity in emotional problems, autistic traits, and wellbeing.

Parent versus child influences on differential parent warmth and discipline within twin pairs.

Parenting behaviors have long been recognized as crucial to children's healthy development. However, examinations of the etiology of these behaviors are less prevalent. The current study investigated the driving forces behind parental warmth and discipline, particularly whether they are related more to traits within the parent or reactions to characteristics of the child. To explore this question, three robust factors of child temperament-effortful control, negative affectivity, and surgency/extraversion-and five parent personality traits were examined in association with parent behaviors through differential parenting within 185 four-year-old twin pairs (370 children; 56% girls; 90% White; predominantly middle class). Genetic analyses showed that parents tend to treat both children similarly in terms of parental warmth, but they treat children less similarly in terms of discipline, regardless of child zygosity. Multilevel linear regressions showed that within twin pairs, the child with higher effortful control received less discipline from parents than their cotwin. Analyses also showed that parent agreeableness was significantly related to parent warmth above and beyond other personality traits and child temperament. This study clarified the direction of effects and genetic contributions to parenting behaviors, supporting previous literature that discipline acts in reaction to the child, whereas warmth is more driven by parent personality. This research suggests the importance of focusing on child temperament and parent personality as they relate to parenting behaviors, allowing clinicians and parents to more effectively correct maladaptive parenting behaviors and encourage healthy and adaptive parenting behaviors, thus promoting positive outcomes for children. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Two babies, two bonds: Frequency and correlates of differential maternal-infant bonding in mothers of twins.

We assessed prevalence and correlates of differential maternal-infant bonding (i.e., experiencing a stronger bond with one baby vs. the other) in mothers of twins, focusing on aspects of maternal mental health, well-being, and pregnancy/birth that have been previously linked with maternal-infant bonding. Participants (N = 108 American women, 88.89% White, 82.41% non-Hispanic, aged 18-45, who gave birth to twins in the past 6-24 weeks) were recruited from postpartum support websites. Participants completed a Qualtrics survey assessing pregnancy/birth history, symptoms of depression and anxiety, sleep, stress, romantic relationship satisfaction, and postpartum bonding. Twenty-six participants (24.07%) reported a bonding discrepancy. These participants endorsed higher symptoms of depression and anxiety, lower relationship satisfaction, lower average postpartum bonding, higher general and parenting stress, and longer pregnancy (all ps > .05). Greater degree of bonding discrepancy correlated with more depression, higher parenting stress, longer pregnancy, and lower relationship satisfaction (all ps > .05). Mothers of twins may benefit from postpartum mental health support, stress management strategies, and interventions to improve bonding. Future work should assess the role of breastfeeding difficulties, delivery method, birth-related trauma, infant regulatory capacity, and temperament. Longitudinal studies will help test cause and effect and potential long-term repercussions of maternal-infant bonding discrepancies.

Evaluamos la prevalencia y factores correlacionados del apego afectivo diferencial materno­infantil (v.g. experimentar un apego más fuerte con un bebé vs. el otro) en madres de gemelos, enfocándonos en aspectos de salud mental materna, bienestar, así como el embarazo/parto que previamente han sido relacionadas con la afectividad materno­infantil. A las participantes (N = 108 mujeres estadounidenses, 88.89% blancas, 82.41% no hispanas, de 18­45 años, que dieron a luz gemelos en las pasadas 6­24 semanas) se les reclutó de los sitios de apoyo posterior al parto en la red. Las participantes completaron una encuesta Qualtrics para evaluar el historial de embarazo/parto, los síntomas de depresión y ansiedad, el sueño, el estrés, la satisfacción con la relación romántica, así como la afectividad posterior al parto. Veintiséis participantes (24.07%) reportaron discrepancia en el apego afectivo. Estas participantes confirmaron síntomas más altos de depresión y ansiedad, más baja satisfacción en la relación, más bajo promedio de apego afectivo posterior al parto, más alto estrés general y de crianza, así como un más largo embarazo (todos los ps > .05). Un mayor grado de discrepancia en el apego afectivo se relacionó con más depresión, un más alto estrés de crianza, un más largo embarazo, así como una más baja satisfacción en la relación (todos los ps > .05). Las madres de gemelos pudieran beneficiarse de un apoyo de salud mental posterior al parto, estrategias de cómo arreglárselas con el estrés e intervenciones para mejorar el apego afectivo. El trabajo futuro debe evaluar el papel de las dificultades de amamantar, el método usado para dar a luz, el trauma relacionado con el nacimiento, la capacidad regulatoria del infante y el temperamento. Estudios longitudinales ayudarán a poner a prueba la causa y el efecto las potenciales repercusiones a largo plazo de las discrepancias en el apego afectivo materno­infantil.

Nous avons évalué la prévalence et les corrélats du lien maternel­bébé différentiel (c'est­à­dire qui font l'expérience d'un lien plus fort avec un bébé par rapport à l'autre) chez les mères de jumeaux ou jumelles, en mettant l'accent sur les aspects de la santé mentale maternelle, le bien­être et la grossesse/naissance ayant précédemment été liés au lien maternel­bébé. Les participantes (N = 108 femmes américaines, 88,89% blanches, 82,41% non­latinas, âgées de 18­45 ans, ayant donné naissance à des jumeaux ou jumelles dans les 6­24 semaines précédentes) ont été recrutées à partir de sites internet de soutien postpartum. Les participantes ont rempli un questionnaire Qualtrics évaluant la grossesse/l'histoire de la naissance, les symptômes de dépression et d'anxiété, le sommeil, le stress, la satisfaction de la relation amoureuse et le lien postpartum. Vingt­six participantes (24,07%) ont fait état d'un écart du lien. Ces participantes ont fait état de plus de symptômes de dépression et d'anxiété, d'une satisfaction avec la relation plus basse, d'un lien postpartum plus bas en moyenne, d'un stress général et parental plus élevé, et d'une grossesse plus longue (tout ps >,05). Un degré plus élevé d'écart du lien a correspondu à plus de dépression, un stress de parentage plus élevé, une grossesse plus longue et une satisfaction de la relation plus basse tous ps > ,05). Les mères de jumeaux ou jumelles peut tirer profit d'un soutien en santé mentale postpartum, de stratégies de gestion du stress, et d'interventions pour améliorer le lien. Dans le futur des recherches devraient évaluer le rôle de difficultés de l'allaitement, la méthode d'accouchement, le trauma lié à la naissance, la capacité régulatoire du bébé et son tempérament. Des études longitudinales permettront de tester la cause et l'effet et les répercussions à long terme potentielle pour les écarts dans le lien maternel­bébé.

Reduction in the use of green spaces during the COVID-19 pandemic and its impact on mental health.

Our study examined the use of green spaces before and during the pandemic in a large cohort of Italian twins and evaluated its impact on measures of mental health (depressive, anxiety, stress symptoms). Twins were analysed as individuals and as pairs. A twin design approach was applied to minimize confounding by genetic and shared environmental factors. Questionnaires from 2,473 twins enrolled in the Italian Twin Registry were screened. Reduced green space use was associated with significantly higher levels of depression, anxiety and distress. Being a woman, residing in urban areas, and having a high perceived risk of the outbreak resulted in a higher likelihood to modify green space use, with a negative impact on mental health.

People's desire to be in nature and how they experience it are partially heritable.

Nature experiences have been linked to mental and physical health. Despite the importance of understanding what determines individual variation in nature experience, the role of genes has been overlooked. Here, using a twin design (TwinsUK, number of individuals = 2,306), we investigate the genetic and environmental contributions to a person's nature orientation, opportunity (living in less urbanized areas), and different dimensions of nature experience (frequency and duration of public nature space visits and frequency and duration of garden visits). We estimate moderate heritability of nature orientation (46%) and nature experiences (48% for frequency of public nature space visits, 34% for frequency of garden visits, and 38% for duration of garden visits) and show their genetic components partially overlap. We also find that the environmental influences on nature experiences are moderated by the level of urbanization of the home district. Our study demonstrates genetic contributions to individuals' nature experiences, opening a new dimension for the study of human-nature interactions.

Are there positive effects of having a sibling with special needs? Empathy and prosociality of twins of children with non-typical development.

This study examined whether typically developing (TD) twins of non-TD children demonstrate enhanced empathy and prosociality. Of 778 Hebrew-speaking Israeli families who participated in a twin study, 63 were identified to have a non-TD child with a TD twin, and 404 as having both twins TD. TD twins of non-TD children (27% males) were compared to the rest of the cohort of TD children (46% males) on measures of empathy and prosociality. Participants were 11 years old. TD twins of non-TD children scored significantly higher than TD twins of TD children in a measure of cognitive empathy (d = .43). No differences were found in emotional empathy and prosociality. The specificity of the positive effect on cognitive empathy is discussed.

Childhood maltreatment and disordered gambling in adulthood: disentangling causal and familial influences.

BACKGROUND: Despite abundant research on the potential causal influence of childhood maltreatment (CM) on psychological maladaptation in adulthood, almost none has implemented the discordant twin design as a means of examining the role of such experiences in later disordered gambling (DG) while accounting for genetic and family environmental confounds. The present study implemented such an approach to disentangle the potential causal and familial factors that may account for the association between CM and DG. METHODS: Participants were 3750 twins from the Australian Twin Registry [Mage = 37.60 (s.d. = 2.31); 58% female]. CM and DG were assessed separately via two semi-structured telephone interviews. Random-intercept generalized linear mixed models were fit to the data; zygosity, sex, educational attainment, childhood psychiatric disorder, adult antisocial behavior, and alcohol use disorder (AUD) were included as covariates. RESULTS: Neither quasi-causal nor familial effects of CM predicted DG after adjusting for covariates. Educational attainment appeared to reduce the risk of DG while AUD appeared to increase risk; evidence also emerged for familial effects of antisocial behavior on DG. Post-hoc analyses revealed a familial effect of CM on antisocial behavior, indicating that the association between CM and DG identified in unadjusted models and in prior studies may be accounted for by genetic and shared family environmental effects of antisociality. CONCLUSIONS: These findings add to the meager literature showing that CM does not exert a causal effect on DG, and present novel evidence that familial effects of antisocial behavior may account for the association between CM and DG identified in extant non-twin research.

Parental criticism and adolescent internalising symptoms: using a Children-of-Twins design with power calculations to account for genetic influence.

BACKGROUND: Parental criticism is correlated with internalising symptoms in adolescent offspring. This correlation could in part reflect their genetic relatedness, if the same genes influence behaviours in both parents and offspring. We use a Children-of-Twins design to assess whether parent-reported criticism and offspring internalising symptoms remain associated after controlling for shared genes. To aid interpretation of our results and those of previous Children-of-Twins studies, we examine statistical power for the detection of genetic effects and explore the direction of possible causal effects between generations. METHODS: Data were drawn from two Swedish twin samples, comprising 876 adult twin pairs with adolescent offspring and 1,030 adolescent twin pairs with parents. Parent reports of criticism towards their offspring were collected concurrently with parent and offspring reports of adolescent internalising symptoms. Children-of-Twins structural equation models were used to control for genetic influence on the intergenerational association between parental criticism and adolescent internalising. RESULTS: Parental criticism was associated with adolescent internalising symptoms after controlling for genetic influence. No significant role was found for shared genes influencing phenotypes in both generations, although power analyses suggested that some genetic effects may have gone undetected. Models could not distinguish directionality for nongenetic, causal effects between generations. CONCLUSIONS: Parental criticism may be involved in psychosocial family processes in the context of adolescent internalising. Future studies should seek to identify these processes and provide clarity on the direction of potential causal effects.

Adolescent cannabis use and adult psychoticism: A longitudinal co-twin control analysis using data from two cohorts.

Observational studies have repeatedly linked cannabis use and increased risk of psychosis. We sought to clarify whether this association reflects a causal effect of cannabis exposure or residual confounding. We analyzed data from two cohorts of twins who completed repeated, prospective measures of cannabis use (N = 1544) and cannabis use disorder symptoms (N = 1458) in adolescence and a dimensional measure of psychosis-proneness (the Personality Inventory for DSM-5 Psychoticism scale) in adulthood. Twins also provided molecular genetic data, which were used to estimate polygenic risk of schizophrenia. Both cumulative adolescent cannabis use and use disorder were associated with higher Psychoticism scores in adulthood. However, we found no evidence of an effect of cannabis on Psychoticism or any of its facets in co-twin control models that compared the greater-cannabis-using twin to the lesser-using co-twin. We also observed no evidence of a differential effect of cannabis on Psychoticism by polygenic risk of schizophrenia. Although cannabis use and disorder are consistently associated with increased risk of psychosis, the present results suggest this association is likely attributable to familial confounds rather than a causal effect of cannabis exposure. Efforts to reduce the prevalence and burden of psychotic illnesses thus may benefit from greater focus on other therapeutic targets. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

On the Genetic and Environmental Relationship Between Suicide Attempt and Death by Suicide.

OBJECTIVE: The authors examined the extent to which the genetic and environmental etiology of suicide attempt and suicide death is shared or unique. METHODS: The authors used Swedish national registry data for a large cohort of twins, full siblings, and half siblings (N=1,314,990) born between 1960 and 1990 and followed through 2015. They conducted twin-family modeling of suicide attempt and suicide death to estimate heritability for each outcome, along with genetic and environmental correlations between them. They further assessed the relationship between suicide attempt by young people compared with adults. RESULTS: In bivariate models, suicide attempt and death were moderately heritable among both women (attempt: additive genetic variance component [A]=0.52, 95% CI=0.44, 0.56; death: A=0.45, 95% CI=0.39, 0.59) and men (attempt: A=0.41, 95% CI=0.38, 0.49; death: A=0.44, 95% CI=0.43, 0.44). The outcomes were substantially, but incompletely, genetically correlated (women: rA=0.67, 95% CI=0.55, 0.67; men: rA=0.74, 95% CI=0.63, 0.87). Environmental correlations were weaker (women: rE=0.36, 95% CI=0.29, 0.45; men: rE=0.21, 95% CI=0.19, 0.27). Heritability of suicide attempt was stronger among people ages 10-24 (A=0.55-0.62) than among those age 25 and older (A=0.36-0.38), and the genetic correlation between attempt during youth and during adulthood was stronger for women (rA=0.79, 95% CI=0.72, 0.79) than for men (rA=0.39, 95% CI=0.26, 0.47). CONCLUSIONS: The genetic and environmental etiologies of suicide attempt and death are partially overlapping, exhibit modest sex differences, and shift across the life course. These differences must be considered when developing prevention efforts and risk prediction algorithms. Where feasible, suicide attempt and death should be considered separately rather than collapsed, including in the context of gene identification efforts.