Psychotic experiences and negative symptoms in the community from adolescence to emerging adulthood

Psychotic experiences and negative symptoms (PENS) reported in non-clinical populations can be viewed as mild manifestations of clinical psychotic symptoms. PENS are reported across the lifespan. They are predictive of poor outcomes, particularly when they persist. Much of the literature has focussed on aggregated measures of psychotic experiences (PEs), and little is known about negative symptoms (NS). Given the known multidimensionality of PENS, this thesis investigates paranoia, hallucinations, and NS, as separate dimensions reported in the community. The focus is on the period from late adolescence to emerging adulthood, a stage of life when many mental health problems occur. Chapter 2 presents analyses that test for longitudinal measurement invariance of the PENS dimensions across the study period. Chapter 3 assesses the optimal form of growth for the PENS dimensions and estimates the sample-wide latent trajectories. Chapter 4 investigates latent heterogeneity in the development of the PENS dimensions. In Chapter 5, the emergent trajectory classes are investigated in terms of the extent to which they associate with background factors reported in childhood/adulthood and with a range of polygenic scores. In Chapter 6, the latent structure of NS is investigated. Associations between polygenic scores and the subdomains of NS are reported. This Thesis provides evidence that PENS dimensions show distinct characteristics, both in terms of development from adolescence to emerging adulthood, and in terms of the correlates that are associated with their development. Evidence is provided to suggest a multidimensional latent structure of NS, mirroring findings from clinical samples. The current findings highlight the value of taking a dimension-specific approach and using latent variable modelling to study PENS over time. Limitations and future research directions are discussed. The findings of this Thesis have implications for future research that aims to test theories relating to the development and maintenance of specific PENS dimensions

Genetic and environmental influences on the stability of psychotic experiences and negative symptoms in adolescence

Background: Psychotic experiences (PEs) such as paranoia and hallucinations, and negative symptoms (NS) such as anhedonia and flat affect, are common in adolescence. PENS increase risk for later psychiatric outcomes, particularly when they persist. The extent to which genetic and environmental influences contribute to the stability of PENS in mid to late adolescence is unknown. Methods: Using the Specific Psychotic Experiences Questionnaire (SPEQ) twice across ~9 months in adolescence, N = 1,448 twin pairs (M = 16.32 (0.68)) reported experiences of paranoia, hallucinations, cognitive disorganisation, grandiosity, and anhedonia, and their parents reported on a range of NS. Individuals were split into lowscoring, decreasing, increasing, and persistent groups for each subscale. Frequencies and mean differences in distress, depression traits, and emotional problems were investigated across groups. Longitudinal structural equation modelling was used to estimate the etiological components underlying the stability of PENS. Results: Phenotypic stability was moderate for all PENS ( r = .59-.69). Persistent PENS across 9 months were associated with greater levels of distress (V = 0.15-0.46, for PEs only), depression traits ( d = 0.47-1.67, except grandiosity), and emotional problems ( d = 0.47-1.47, except grandiosity and anhedonia) at baseline compared to groups with transitory or low levels of PENS. At both ages PENS were heritable and influenced by shared and nonshared environment. Genetic influences contributed 38%-62%, and shared environment contributed 13%-33% to the stability of PENS. Nonshared environment contributed 34%-41% (12% for parent-rated NS). There was strong overlap of genetic and shared environmental influences across time, and lower overlap for nonshared environment. Imperfect stability of PENS was at least partly due to non-shared environmental influences. Conclusions: When adolescent PENS persist over time, they are often characterised by more distress, and higher levels of other psychopathology. Both genetic and environmental effects influence stability of PENS

The latent structure of negative symptoms in the general population in adolescence and emerging adulthood

Negative symptoms predict adverse outcomes within psychotic disorders, in individuals at high-risk for psychosis, and in young people in the community. There is considerable interest in the dimensional structure of negative symptoms in clinical samples, and accumulating evidence suggests a 5-factor structure. Little is known about the underlying structure of negative symptoms in young people despite the importance of this developmental stage for mental health. We used confirmatory factor analysis to test the structure of parent-reported negative symptoms at mean ages 16.32 (SD 0.68, N = 4974), 17.06 (SD 0.88, N = 1469) and 22.30 (SD 0.93, N = 5179) in a community sample. Given previously reported associations between total negative symptoms and genome-wide polygenic scores (GPS) for major depressive disorder (MDD) and schizophrenia in adolescence, we assessed associations between individual subdomains and these GPSs. A 5-factor model of flat affect, alogia, avolition, anhedonia, and asociality provided the best fit at each age and was invariant over time. The results of our linear regression analyses showed associations between MDD GPS with avolition, flat affect, anhedonia, and asociality, and between schizophrenia GPS with avolition and flat affect. We showed that a 5-factor structure of negative symptoms is present from ages 16 to 22 in the community. Avolition was most consistently associated with polygenic liability to MDD and schizophrenia, and alogia was least associated. These findings highlight the value of dissecting negative symptoms into psychometrically derived subdomains and may offer insights into early manifestation of genetic risk for MDD and schizophrenia

Psychotic experiences and negative symptoms from adolescence to emerging adulthood: developmental trajectories and associations with polygenic scores and childhood characteristics

Background. Psychotic experiences and negative symptoms (PENS) are common in nonclinical populations. PENS are associated with adverse outcomes, particularly when they persist. Little is known about the trajectories of PENS dimensions in young people, nor about the precursory factors associated with these trajectories. Methods. We conducted growth mixture modelling of paranoia, hallucinations, and negative symptoms across ages 16, 17, and 22 in a community sample (N = 12 049–12 652). We then described the emergent trajectory classes through their associations with genome-wide polygenic scores (GPS) for psychiatric and educational phenotypes, and earlier childhood characteristics. Results. Three trajectory classes emerged for paranoia, two for hallucinations, and two for negative symptoms. Across PENS, GPS for clinical help-seeking, major depressive disorder, and attention deficit hyperactivity disorder were associated with increased odds of being in the most elevated trajectory class (OR 1.07–1.23). Lower education GPS was associated with the most elevated trajectory class for hallucinations and negative symptoms (OR 0.77– 0.91). Conversely for paranoia, higher education GPS was associated with the most elevated trajectory class (OR 1.25). Trajectory class associations were not significant for schizophrenia, obsessive-compulsive disorder, bipolar disorder, or anorexia GPS. Emotional/behaviour problems and life events in childhood were associated with increased odds of being in the most elevated trajectory class across PENS. Conclusions. Our results suggest latent heterogeneity in the development of paranoia, hallucinations, and negative symptoms in young people that is associated with specific polygenic scores and childhood characteristics

Youth adversity and trajectories of depression/anxiety symptoms in adolescence in the context of intersectionality in the United Kingdom

Background Youth adversity is associated with persistence of depression and anxiety symptoms. This association may be greater for disadvantaged societal groups (such as females) compared with advantaged groups (e.g. males). Given that persistent symptoms are observed across a range of disadvantaged, minoritized, and neurodivergent groups (e.g. low compared with high socio-economic status [SES]), the intersection of individual characteristics may be an important moderator of inequality. Methods Data from HeadStart Cornwall (N = 4441) was used to assess the effect of youth adversity on combined symptoms of depression and anxiety (Strengths and Difficulties Questionnaire emotional problems subscale) measured at three time-points in 11–14-year-olds. Latent trajectories and regressions were estimated for eight intersectionality profiles (based on gender, SES, and hyperactivity/inattention), and moderating effects of the individual characteristics and their intersections were estimated. Results Youth adversity was associated with higher average depression/anxiety symptoms at baseline (11–12-years) across all intersectionality profiles. The magnitude of effects differed across profiles, with suggestive evidence for a moderating effect of youth adversity on change over time in depression/anxiety symptoms attributable to the intersection between (i) gender and SES; and (ii) gender, SES, and hyperactivity/inattention. Conclusions The detrimental effects of youth adversity pervade across intersectionality profiles. The extent to which these effects are moderated by intersectionality is discussed in terms of operational factors. The current results provide a platform for further research, which is needed to determine the importance of intersectionality as a moderator of youth adversity on the development of depression and anxiety symptoms in adolescence

The impact of intersectionality profiles on the relation between early adverse experiences and emotional problems in adolescence

Early adverse experiences such as abuse and bullying victimisation are robust predictors of poor mental health later in life (Bellis et al., 2019). There is initial evidence which indicates that the strength of this relation varies by individual characteristics, such as gender and ethnicity (e.g., Jones et al., 2022; Forster et al., 2018; Lee & Chen, 2017; Schilling et al., 2007). There are also findings to suggest that the intersection between these characteristics (e.g., female and ethnic minority) is associated with later mental health (Kern et al., 2020), and early adverse experiences (Ickert et al., 2022; Mersky et al., 2021). However, there are no published findings to our knowledge that consider the impact of the intersection between individual characteristics (e.g., female and ethnic minority) on the relation between early adverse experiences and mental health. According to intersectionality theory, individual characteristics (e.g., gender and ethnicity) that reflect proxies for social oppression and privilege, interact to give rise to unique social experience. Gaining an understanding of the extent to which and the ways in which intersectionality profiles are associated with risk of and resilience to psychopathology in the face of early adversity, requires the inclusion of diverse representative samples. Here, we present a preregistration for the OxWell project as part of the ATTUNE project Work Package 2, which aims to investigate early adversity and mental health in young people in the community in the context of intersectionality, using existing datasets

Change to a Plant-Based Diet Has No Effect on Strength Performance in Trained Persons in the First 8 Weeks—A 16-Week Controlled Pilot Study

Over the past few years, the number of people who have avoided animal products has been rising steadily. A plant-based diet is associated with a healthier lifestyle and has positive effects on various diseases. More and more healthy active people and performance-orientated athletes are giving up animal products for various reasons, such as for an improved performance or faster regeneration. However, the data in this context are limited. This study aimed to obtain initial findings on the influence of a diet change to veganism on the performance of strength-trained individuals. For this study, a total of 15 omnivorous individuals were recruited. They documented their dietary food intakes over 16 weeks. Every four weeks, the strength performance was tested via a leg press and bench press. In the first 8 weeks, the participants maintained their omnivorous diet, followed by 8 weeks of a vegan dietary phase. In total, 10 subjects participated successfully, and their data were part of the statistical analyses. There was no difference in the absolute and relative strength performance for the leg and bench press after changing to a vegan diet. For the total calorie intake and carbohydrates, only a small treatment effect, but no time effect, was observed. However, for the protein intake, a time and group effect were detected. In addition, the relative protein intake decreased significantly and was lower than the current recommendations for athletes. The results demonstrate that a change to a vegan diet has no beneficial nor negative effect on the strength performance when the total calorie intake and carbohydrate content are covered in the first 8 weeks

A cross-sectional investigation into the role of intersectionality as a moderator of the relation between youth adversity and adolescent depression/anxiety symptoms in the community

Background: Adolescents exposed to adversity show higher levels of depression and anxiety, with the strongest links seen in disadvantaged (e.g., females, low socioeconomic status [SES]), as well as neurodivergent, groups. The intersection of these characteristics may moderate the impact of youth adversity on adolescent mental health. Aims: To investigate the moderating influence of intersectionality on the relation between youth adversity and depression and anxiety symptoms in adolescence. Methods: Depression and anxiety symptoms were measured in 13-14-year-olds in the HeadStart Cornwall cohort (N=12,067) using the emotional problems subscale of the Strengths and Difficulties Questionnaire. Multiple group structural equation modelling was used to estimate the effects of youth adversity on combined depression and anxiety symptoms across eight intersectionality profiles. Group assignment was based on gender (female/male), SES (lower/higher), and hyperactivity/inattention (high/low). Moderation effects attributable to these characteristics and their intersections were estimated. Results: Youth adversity was associated with higher levels of depression and anxiety (compared to an absence of youth adversity), across intersectional profiles. This association was moderated by gender (stronger in males than females (β=0.22 [0.11,0.36])), and SES (stronger in higher compared to lower SES (β=0.26 [0.14,0.40])); with indications of moderation attributable to the intersection of gender and hyperactivity/inattention (β=0.21 [-0.02,0.44]). Conclusions: Youth adversity detrimentally impacts the mental health of 13-14-year-olds, across intersectional profiles. Preliminary findings suggest that vulnerability and resilience to the negative impacts of youth adversity may partially depend on the intersection of individual characteristics. These results invite further investigation in this emerging field of research