Early-life residential green spaces and traffic exposure in association with young adult body composition: a longitudinal birth cohort study of twins.

BACKGROUND: Globally, the rapid increase of obesity is reaching alarming proportions. A new approach to reduce obesity and its comorbidities involves tackling the built environment. Environmental influences seem to play an important role, but the environmental influences in early life on adult body composition have not been thoroughly investigated. This study seeks to fill the research gap by examining early-life exposure to residential green spaces and traffic exposure in association with body composition among a population of young adult twins. METHODS: As part of the East Flanders Prospective Twin Survey (EFPTS) cohort, this study included 332 twins. Residential addresses of the mothers at time of birth of the twins were geocoded to determine residential green spaces and traffic exposure. To capture body composition, body mass index, waist-to-hip ratio (WHR), waist circumference, skinfold thickness, leptin levels, and fat percentage were measured at adult age. Linear mixed modelling analyses were conducted to investigate early-life environmental exposures in association with body composition, while accounting for potential confounders. In addition, moderator effects of zygosity/chorionicity, sex and socio-economic status were tested. RESULTS: Each interquartile range (IQR) increase in distance to highway was found associated with an increase of 1.2% in WHR (95%CI 0.2-2.2%). For landcover of green spaces, each IQR increase was associated with 0.8% increase in WHR (95%CI 0.4-1.3%), 1.4% increase in waist circumference (95%CI 0.5-2.2%), and 2.3% increase in body fat (95%CI 0.2-4.4%). Stratified analyses by zygosity/chorionicity type indicated that in monozygotic monochorionic twins, each IQR increase in land cover of green spaces was associated with 1.3% increase in WHR (95%CI 0.5-2.1%). In monozygotic dichorionic twins, each IQR increase in land cover of green spaces was associated with 1.4% increase in waist-circumference (95%CI 0.6-2.2%). CONCLUSIONS: The built environment in which mothers reside during pregnancy might play a role on body composition among young adult twins. Our study revealed that based on zygosity/chorionicity type differential effects of prenatal exposure to green spaces on body composition at adult age might exist.

Polygenic liability for schizophrenia and childhood adversity influences daily-life emotion dysregulation and psychosis proneness.

OBJECTIVE: To test whether polygenic risk score for schizophrenia (PRS-S) interacts with childhood adversity and daily-life stressors to influence momentary mental state domains (negative affect, positive affect, and subtle psychosis expression) and stress-sensitivity measures. METHODS: The data were retrieved from a general population twin cohort including 593 adolescents and young adults. Childhood adversity was assessed using the Childhood Trauma Questionnaire. Daily-life stressors and momentary mental state domains were measured using ecological momentary assessment. PRS-S was trained on the latest Psychiatric Genetics Consortium schizophrenia meta-analysis. The analyses were conducted using multilevel mixed-effects tobit regression models. RESULTS: Both childhood adversity and daily-life stressors were associated with increased negative affect, decreased positive affect, and increased subtle psychosis expression, while PRS-S was only associated with increased positive affect. No gene-environment correlation was detected. There is novel evidence for interaction effects between PRS-S and childhood adversity to influence momentary mental states [negative affect (b = 0.07, P = 0.013), positive affect (b = -0.05, P = 0.043), and subtle psychosis expression (b = 0.11, P = 0.007)] and stress-sensitivity measures. CONCLUSION: Exposure to childhood adversities, particularly in individuals with high PRS-S, is pleiotropically associated with emotion dysregulation and psychosis proneness.

Is sensitivity to daily stress predictive of onset or persistence of psychopathology?

PURPOSE: The aim of the current study was to replicate findings in adults indicating that higher sensitivity to stressful events is predictive of both onset and persistence of psychopathological symptoms in a sample of adolescents and young adults. In addition, we tested the hypothesis that sensitivity to mild stressors in particular is predictive of the developmental course of psychopathology. METHODS: We analyzed experience sampling and questionnaire data collected at baseline and one-year follow-up of 445 adolescent and young adult twins and non-twin siblings (age range: 15-34). Linear multilevel regression was used for the replication analyses. To test if affective sensitivity to mild stressors in particular was associated with follow-up symptoms, we used a categorical approach adding variables on affective sensitivity to mild, moderate and severe daily stressors to the model. RESULTS: Linear analyses showed that emotional stress reactivity was not associated with onset (ß=.02; P=.56) or persistence (ß=-.01; P=.78) of symptoms. There was a significant effect of baseline symptom score (ß=.53; P<.001) and average negative affect (NA: ß=.19; P<.001) on follow-up symptoms. Using the categorical approach, we found that affective sensitivity to mild (ß=.25; P<.001), but not moderate (ß=-.03; P=.65) or severe (ß=-.06; P=.42), stressors was associated with symptom persistence one year later. DISCUSSION: We were unable to replicate previous findings relating stress sensitivity linearly to symptom onset or persistence in a younger sample. Whereas sensitivity to more severe stressors may reflect adaptive coping, high sensitivity to the mildest of daily stressors may indicate an increased risk for psychopathology.

Placental telomere length decreases with gestational age and is influenced by parity: a study of third trimester live-born twins.

BACKGROUND: In contrast to the postnatal period, little is known about telomere length (TL) during prenatal life. The decrease in placental TL remains unknown, although intra uterine growth retardation and preeclampsia are associated with shorter placental TL. The aim of this study is to assess the decrease of placental TL during the third trimester of gestation and to explore the role of potential "growth influencing factors". METHODS: The study sample consisted of 329 live-born twins from the East Flanders Prospective Twin Survey. TL was determined using a multiplex quantitative PCR method. Gestational age, sex, birth order, placental characteristics, parity, maternal and paternal age, diabetes, hypertension, smoking, alcohol use, and socio economic status (SES) were considered "growth influencing factors". Bivariable multilevel regression analysis with "growth influencing factors" was performed. RESULTS: Placental TL ranged from 4.3 kbp to 84.4 kbp with a median of 10.8 kbp. Ln(TL) decreased in a linear fashion with an estimated TL decreasing from 13.98 kbp at 28 weeks to 10.56 kbp at 42 weeks. The regression coefficient of gestational age became smaller if considered together with SES (b = -0.017; p = 0.08) or diabetes (b = -0.018; p = 0.07) and bigger if considered together with parity (b = -0.022; p = 0.02), indicating that part of the association between gestational age and telomere length is explained by these three confounding factors. CONCLUSION: Placental TL decreases during the third trimester of gestation of live-born twins with approximately 25% indicating that telomere shortening may play a role in aging of the placenta.

Heritability and genetic etiology of habitual physical activity: a twin study with objective measures.

Twin studies with objective measurements suggest habitual physical activity (HPA) are modestly to highly heritable, depending on age. We aimed to confirm or refute this finding and identify relevant genetic variants using a candidate gene approach. HPA was measured for 14 days with a validated triaxial accelerometer (Tracmor) in two populations: (1) 28 monozygotic and 24 dizygotic same-sex twin pairs (aged 22 ± 5 years, BMI 21.8 ± 3.4 kg/m(2), 21 male, 31 female pairs); (2) 52 and 65 unrelated men and women (aged 21 ± 2 years, BMI 22.0 ± 2.5 kg/m(2)). Single nucleotide polymorphisms (SNPs) in PPARD, PPARGC1A, NRF1 and MTOR were considered candidates. Association analyses were performed for both groups separately followed by meta-analysis. Structural equation modeling shows significant familiality for HPA, consistent with a role for additive genetic factors (heritability 57 %, 95 % CI 32-74 %, AE model) or common environmental factors (47 %, 95 % CI 23-65 %, CE model). A moderate heritability was observed for the time spent on low- and high-intensity physical activity (P ≤ 0.05), but could not be confirmed for the time spent on moderate-intensity physical activity. For PPARD, each additional effect allele was inversely associated with HPA (P ≤ 0.01; rs2076168 allele C) or tended to be associated with HPA (P ≤ 0.05; rs2267668 allele G). Linkage disequilibrium existed between those two SNPs (alleles A/G and A/C, respectively) and meta-analysis showed that carriers of the AA GC haplotype were less physically active than carriers of the AA AA and AA AC haplotypes combined (P = 0.017). For PPARGC1A, carriers of AA in rs8192678 spent more time on high-intensity physical activity than GG carriers (P = 0.001). No associations were observed with SNPs in NRF1 and MTOR. In conclusion, HPA may be modestly heritable, which is confirmed by an association with variants in PPARD.

Positive emotions from social company in women with persisting subclinical psychosis: lessons from daily life.

OBJECTIVE: Altered social reward functioning is associated with psychosis irrespective of stage and severity. Examining the role of social reward functioning prospectively in relation to psychotic experiences before these become persistent and potentially disabling can aid in elucidating social mechanisms that induce shifts toward more severe psychotic states, without the confounding effects of clinical disorder. METHOD: In a longitudinal general population sample (N = 566), the experience sampling method (repetitive random sampling of momentary emotions and social context) was used to assess daily life social functioning at baseline. Persistence of subclinical psychotic experiences was based on the Community Assessment of Psychic Experiences assessed three times over 14 months. Analyses examined to what degree i) social context and ii) appreciation thereof differentiated between those who did and did not develop persistent psychotic experiences. RESULTS: Although individuals with persistent psychotic experiences did not differ in overall level of positive effect, the amount of time spent alone or the level of social satisfaction compared to individuals without persistent psychotic experiences, they were more sensitive to the rewarding effects of social company. CONCLUSION: Alterations in social reward experience may form one of the mechanisms that precede the development of the extended psychosis phenotype over time.

Deconstructing the familiality of variability in momentary negative and positive affect.

OBJECTIVE: The daily life, affective phenotypes of momentary negative affect (NA), positive affect (PA) variability and NA variability are associated with future depressive symptomatology. This study investigates the extent to which genetic and environmental factors contribute to the inter-individual differences in these daily life, affective phenotypes. METHOD: Two hundred and seventy-nine female twins from the Flemish (Belgium) general population participated in an experience sampling study measuring affect in daily life. Structural equation modelling was used to fit univariate and bivariate models. RESULTS: Genetic factors explained, respectively, 18%, 18% and 35% of the inter-individual differences in momentary NA, PA variability and NA variability. Non-shared environmental factors were found to explain the remaining inter-individual variation. In addition, 41% of the association between positive and NA variability was attributed to shared genetic factors. CONCLUSION: Results of this study show that daily life patterns of affective expression are subject to substantial environmental influence. Prospective assessments of the effect of interventions on these expressions may therefore represent a powerful tool to prevent transition from subclinical depressive symptomatology to a clinical outcome or to reduce symptomatology in those with clinical depression.

Intrauterine environment and cognitive development in young twins.

Intrauterine factors important for cognitive development, such as birth weight, chorionicity and umbilical cord characteristics were investigated. A total of 663 twin pairs completed the Wechsler Intelligence Scale for Children-Revised and scores were available for Performance, Verbal and Total Intelligence Quotient (IQ). The intrauterine factors examined were birth weight, placental weight and morphology, cord knots, cord length and cord insertion. IQ scores for the varying levels of the intrauterine markers adjusting for gender and gestational age were calculated. The heritability of IQ and the association between IQ and intrauterine environment were examined. Twins with lower birth weight and cord knots had lower IQ scores. The aetiology of IQ is largely distinct from that of birth weight and cord knots, and non-shared environment may influence the observed relationships.

Disentangling the causal inter-relationship between negative life events and depressive symptoms in women: a longitudinal twin study.

BACKGROUND: Negative life events are strongly associated with the development of depression. However, the etiologic relationship between life events and depression is complex. Evidence suggests that life events can cause depression, and depression increases the risk for life events. Additionally, third factors influencing both phenotypes may be involved. In this work we sought to disentangle these relationships using a genetically informative longitudinal design. METHOD: Adult female twins (n=536, including 281 twin pairs) were followed up for measurements of negative life event exposure and depressive symptoms. Four follow-ups were completed, each approximately 3 months apart. Model fitting was carried out using the Mx program. RESULTS: The best-fitting model included causal paths from life events to depressive symptoms for genetic and shared environmental risk factors, whereas paths from depressive symptoms to life events were apparent for shared environmental factors. Shared latent influence on both phenotypes was found for individual-specific effects. CONCLUSIONS: Life events and depressive symptoms have complex inter-relationships that differ across sources of variance. The results of the model, if replicated, indicate that reducing life event exposure would reduce depressive symptoms and that lowering depressive symptoms would decrease the occurrence of negative life events.

Evidence that genes for depression impact on the pathway from trauma to psychotic-like symptoms by occasioning emotional dysregulation.

BACKGROUND: Genes for depression may act by making individuals more sensitive to childhood trauma. Given that childhood adversity is a risk factor for adult psychosis and symptoms of depression and psychosis tend to cluster within individuals and families, the aim was to examine whether the association between childhood adversity and psychotic-like symptoms is moderated by genetic liability for depression. A secondary aim was to determine to what degree a depression-related increase in stress sensitivity or depressive symptoms themselves occasioned the moderating effect. METHOD: Female twins (n=508) completed both prospective and retrospective questionnaires regarding childhood adversity [the Symptom Checklist-90 - Revised (SCL-90-R) and SCID-I (psychotic symptoms)] and psychotic trait liability [the Community Assessment of Psychic Experiences (CAPE)]. Stress sensitivity was indexed by appraisals of event-related stress and negative affect (NA) in the flow of daily life, assessed with momentary assessment technology for five consecutive days. Multilevel regression analyses were used to examine moderation of childhood adversity by genetic liability for depression in the prediction of follow-up psychotic experiences. RESULTS: The effect of childhood adversity was significantly moderated by genetic vulnerability for depression in the model of both follow-up psychotic experiences (SCL-90-R) and follow-up psychotic trait liability (CAPE). The moderation by genetic liability was mediated by depressive experience but not by stress sensitivity. CONCLUSIONS: Genetic liability for depression may potentiate the pathway from childhood adversity to psychotic-like symptoms through dysfunctional emotional processing of anomalous experiences associated with childhood trauma.

Neuroticism explained? From a non-informative vulnerability marker to informative person-context interactions in the realm of daily life.

OBJECTIVES: Despite the well-replicated finding that neuroticism is associated with increased susceptibility for psychopathology, it remains unclear what 'vulnerability as indexed by neuroticism' represents in terms of everyday life emotional processes. This study examined the association between neuroticism and six phenotypes of daily life emotional responses: positive affect (PA), negative affect (NA), PA variability, NA variability, stress sensitivity, and reward experience, and investigated the contribution of genetic and environmental factors to these associations. DESIGN: A prospective cohort study in a population-based sample of 416 adult female twins. METHOD: A momentary assessment approach (experience sampling method) was used to collect multiple assessments of affect in daily life. Neuroticism was assessed with the Eysenck Personality Scale. Multi-level regression analyses were carried out to examine the association between neuroticism and the phenotypes of daily life emotional responses. Cross-twin, cross-trait analyses, and bivariate structural equation modelling (SEM) were performed in order to investigate the nature of these associations. RESULTS: A high neuroticism score was associated with lower momentary PA levels and increased NA variability, independent of momentary NA, PA variability, stress sensitivity, and reward experience. Both the cross-twin, cross-trait analyses, and the bivariate SEM showed that unique, non-shared environmental factors drive the association between neuroticism and PA and that the association between neuroticism and increased NA variability is based on shared genetic factors as well as individual-specific environmental factors. CONCLUSIONS: Neuroticism as measured by Eysenck questionnaire may index an environmental risk for decreased daily life PA levels and a genetic as well as an environmental risk for increased NA variability. Decomposing the broad measure of neuroticism into measurable persons-context interactions increases its 'informative' value in explaining psychopathology.

Life events and borderline personality features: the influence of gene-environment interaction and gene-environment correlation.

BACKGROUND: Traumatic life events are generally more common in patients with borderline personality disorder (BPD) than in non-patients or patients with other personality disorders. This study investigates whether exposure to life events moderates the genetic architecture of BPD features. As the presence of genotype-environment correlation (rGE) can lead to spurious findings of genotype-environment interaction (G × E), we also test whether BPD features increase the likelihood of exposure to life events. METHOD: The extent to which an individual is at risk to develop BPD was assessed with the Personality Assessment Inventory - Borderline features scale (PAI-BOR). Life events under study were a divorce/break-up, traffic accident, violent assault, sexual assault, robbery and job loss. Data were available for 5083 twins and 1285 non-twin siblings. Gene-environment interaction and correlation were assessed by using structural equation modelling (SEM) and the co-twin control design. RESULTS: There was evidence for both gene-environment interaction and correlation. Additive genetic influences on BPD features interacted with the exposure to sexual assault, with genetic variance being lower in exposed individuals. In individuals who had experienced a divorce/break-up, violent assault, sexual assault or job loss, environmental variance for BPD features was higher, leading to a lower heritability of BPD features in exposed individuals. Gene-environment correlation was present for some life events. The genes that influence BPD features thus also increased the likelihood of being exposed to certain life events. CONCLUSIONS: To our knowledge, this study is the first to test the joint effect of genetic and environmental influences and the exposure to life events on BPD features in the general population. Our results indicate the importance of both genetic vulnerability and life events.

Secular trends in gestational age and birthweight in twins.

BACKGROUND: In recent decades, the overall rate of preterm births has increased. The aim of the present study was to examine whether this trend is also seen for multiple gestations. More specifically, we examined if there has been a decrease in gestational age for live born monozygotic (MZ) and dizygotic (DZ) twins and if there has been a simultaneous change in birthweight. The contributions of fertility treatments and Caesarean sections were taken into consideration. All analyses were carried out in two large European twin cohorts. METHODS: Cross-sectional study of 6310 live born twin pairs, born between 1964-2007, from the Belgian East Flanders Prospective Twin Survey and 14,712 twin pairs, born between 1990-2006, from the Netherlands Twin Register. Multiple regression analyses were performed with gestational age as outcome variable, and multilevel analysis with birthweight as outcome variable. All analyses were performed with and without adjustment for zygosity, parity, maternal age, mode of conception and delivery and, for the analyses of birthweight, gestational age. RESULTS: Gestational age decreased in a linear fashion from 1964 to 2007 with a decrease of 0.25 days per year in a similar way for MZ and DZ twins. Changes in birthweight depended on gestational age: up to 32 weeks, birthweight decreased and after 32 weeks birthweight increased. The frequency of infertility treatment and Caesarean sections, primiparity and advanced maternal age increased over the years, but none of these factors influenced the secular trends in gestational age and birthweight. CONCLUSIONS: The decrease in gestational age and change in birthweight in twins are sources of concern, especially for very preterm twins, for whom birthweight decreased. For twins born after 32 weeks, an increase in birthweight was observed and this is very likely the explanation for the decrease in gestational age.

No major role for X-inactivation in variations of intelligence and behavioral problems at middle childhood.

Although members of monozygotic (MZ) twin pairs are identical in genomic sequence, epigenetic mechanisms may occasion difference in gene expression and, consequently, twin discordance in complex traits. Recent work suggests that the epigenetic process of X-inactivation in female individuals may impact on intelligence and child behavioral problems. The timing of X-inactivation has been linked to chorionic splitting in MZ twins. Dichorionic monozygotic (DC-MZ) twinning, unlike monochorionic monozygotic (MC-MZ) twinning, occurs prior to the time of X-inactivation in female organisms. Therefore, the hypothesis of a causal role of X-inactivation in intelligence and behavioral problems can be analyzed by modeling the statistical interaction between sex and chorion type for within-pair differences in these traits in MZ twins. In this study, the effect of X-inactivation on childhood behavioral problems, measured with the CBCL, was studied in a sample of 324 MZ twin pairs from the EFPTS and the effect of X-inactivation on IQ was studied in a sample of 272 twin pairs from the same twin survey. Information on chorion type, gestational age, and birth weight was additionally collated. No significant statistical interaction was found between sex and chorion type, indicating that X-inactivation is not likely involved in variations in intelligence or behavioral problems in middle childhood. Further studies are required to replicate these findings and may explore the role of X-inactivation at different ages or at the extreme scores in the spectrum of intelligence and behavioral problems or may focus on other epigenetic mechanisms.

Meeting risk with resilience: high daily life reward experience preserves mental health.

OBJECTIVE: To examine prospectively whether high reward experience (the ability to generate positive affect boosts from pleasurable daily events) protects against affective symptoms and whether environmental or genetic risk factors moderate protective effects. METHOD: At baseline, 498 female twins participated in an experience sampling study measuring reward experience in daily life. They also completed questionnaires on childhood adversity and recent stressful life events (SLE). Affective symptoms were measured at baseline and at four follow-ups using SCL-90 anxiety and depression subscales. Co-twin affective symptoms were used as indicators of genetic risk. RESULTS: Baseline reward experience did not predict follow-up affective symptoms, regardless of level of genetic risk. However, high reward experience was associated with reduced future affective symptoms after previous exposure to childhood adversity or recent SLE. CONCLUSION: High daily life reward experience increases resilience after environmental adversity; modification of reward experience may constitute a novel area of therapeutic intervention.

Unveiling patterns of affective responses in daily life may improve outcome prediction in depression: a momentary assessment study.

OBJECTIVE: Daily life affective responses are closely linked to vulnerability and resilience in depression. Prediction of future clinical course may be improved if information on daily life emotional response patterns is taken into account. METHOD: Female subjects with a history of major depression (n=83), recruited from a population twin register, participated in a longitudinal study using momentary assessment technology with 4 follow-up measurements. The effect of baseline daily life emotional response patterns (affect variability, stress-sensitivity and reward experience) on follow-up depressive symptomatology was examined. RESULTS: Both reward experience (B=-0.30, p=0.001) and negative affect variability (B=0.46, p=0.001) predicted future negative affective symptoms independent of all other dynamic emotional patterns and conventional predictors. CONCLUSION: Daily life information on dynamic emotional patterns adds to the prediction of future clinical course, independent of severity of symptoms and neuroticism score. Better prediction of course may improve decision-making regarding quantitative and qualitative aspects of treatment.

Parent-of-origin specific linkage and association of the IGF2 gene region with birth weight and adult metabolic risk factors.

OBJECTIVE: The maternally imprinted insulin-like growth factor 2 (IGF2) gene is an important fetal growth factor and is also suggested to have postnatal metabolic effects. In this study, we examined whether common polymorphisms in IGF2 (6815_6819delAGGGC, 1156T>C and 820G>A (ApaI)) and a microsatellite marker in the close vicinity of IGF2 were linked to or associated with birth weight and adult metabolic risk factors. DESIGN AND PARTICIPANTS: Polymorphisms were genotyped in 199 monozygotic complete twin pairs, 109 dizygotic complete twin pairs, 15 single twins, 231 mothers and 228 fathers recruited from the East Flanders Prospective Twin Survey. Conventional and parent-of-origin specific linkage and association analyses were carried out with birth weight, adult body height and parameters quantifying obesity, insulin sensitivity and dyslipidaemia measured at adult age (mean age 25 years). RESULTS: In the parent-of-origin specific association analysis, in which only the paternally inherited allele was incorporated, the 1156T>C SNP (single nucleotide polymorphism) showed significant association with IGF-binding protein 1 (IGFBP1) levels (T and C (mean (95% CI)): 13.2 (12.1-14.3) and 16.2 (14.6-18.0) ng ml(-1), P=0.002). No linkage was observed in either the conventional or in the parent-of-origin specific linkage analysis. CONCLUSION: This study suggests that paternally inherited alleles of a common polymorphism in the IGF2 gene affect IGFBP1 levels.

Cognition as predictor of current and follow-up depressive symptoms in the general population.

OBJECTIVE: Previous studies have reported an association between depression and poor cognitive functioning. Unknown is to what degree such associations are merely state-related or reflect an enduring depression vulnerability. This study examined whether cognitive deficits predict current and/or follow-up (sub)clinical depressive symptoms in the general population. METHOD: A population-based sample of 569 female twins and 43 of their sisters completed a neuropsychological battery. Cross-sectional and prospective associations between depressive symptoms measured at the subclinical [Symptom Checklist-90 (SCL-90)] and clinical level (Structured Clinical Interview for DSM-IV disorders) and neuropsychological factors (episodic memory and information processing speed) were examined. RESULTS: Structured Clinical Interview for DSM-IV disorders baseline depressive symptoms were significantly associated with information processing speed but not with episodic memory. Episodic memory was significantly associated with follow-up SCL-90 depressive symptoms. CONCLUSION: Being depressed is accompanied by slower information processing. Poor memory functioning may be a predictor for the onset of subclinical depressive symptoms.

Does reactivity to stress cosegregate with subclinical psychosis? A general population twin study.

OBJECTIVE: This study assessed the relationship between stress reactivity (trait 1) and psychosis (trait 2) across genetically related persons (cross-twin, cross-trait design) to examine whether stress reactivity is an uncontaminated and unconfounded familial marker of psychosis risk. METHOD: Reactivity to stress and subclinical psychotic experiences were assessed in 289 female, general population twin-pairs. Cross-trait, within-twin associations investigating the association between stress reactivity and subclinical psychotic experiences in each person, were calculated. In addition, cross-trait, cross-twin associations were calculated to assess whether stress reactivity in one twin was moderated by subclinical psychotic experiences in the co-twin. RESULTS: Cross-trait, within-twin analyses showed significant associations between stress reactivity and subclinical psychotic experiences in each person. In addition, the cross-trait cross-twin analyses showed that stress reactivity in twin 1 was significantly moderated by subclinical experiences in the co-twin. CONCLUSION: The results suggest that the psychosis phenotype cosegregates with increased emotional reactivity to stress in daily life.