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

Research Review: A review of the past decade of family and genomic studies on adolescent mental health

BACKGROUND

Mental health problems and traits capturing psychopathology are common and often begin during adolescence. Decades of twin studies indicate that genetic factors explain around 50% of individual differences in adolescent psychopathology. In recent years, significant advances, particularly in genomics, have moved this work towards more translational findings.

METHODS

This review provides an overview of the past decade of genetically sensitive studies on adolescent development, covering both family and genomic studies in adolescents aged 10-24 years. We focus on five research themes: (1) co-occurrence or comorbidity between psychopathologies, (2) stability and change over time, (3) intergenerational transmission, (4) gene-environment interplay, and (5) psychological treatment outcomes.

RESULTS

First, research shows that much of the co-occurrence of psychopathologies in adolescence is explained by genetic factors, with widespread pleiotropic influences on many traits. Second, stability in psychopathology across adolescence is largely explained by persistent genetic influences, whereas change is explained by emerging genetic and environmental influences. Third, contemporary twin-family studies suggest that different co-occurring genetic and environmental mechanisms may account for the intergenerational transmission of psychopathology, with some differences across psychopathologies. Fourth, genetic influences on adolescent psychopathology are correlated with a wide range of environmental exposures. However, the extent to which genetic factors interact with the environment remains unclear, as findings from both twin and genomic studies are inconsistent. Finally, a few studies suggest that genetic factors may play a role in psychological treatment response, but these findings have not yet been replicated.

CONCLUSIONS

Genetically sensitive research on adolescent psychopathology has progressed significantly in the past decade, with family and twin findings starting to be replicated at the genomic level. However, important gaps remain in the literature, and we conclude by providing suggestions of research questions that still need to be addressed.

Sleep and paranoia: A systematic review and meta-analysis

BACKGROUND

Sleep dysfunction commonly co-occurs with paranoia and is hypothesised to be a contributory causal mechanism in its development and maintenance.

OBJECTIVES

To systematically review and quantitatively evaluate the evidence for the relationship between sleep dysfunction and paranoia across the spectrum of severity.

METHOD

A systematic search was conducted to identify studies investigating the relationship between aspects of sleep and paranoia across clinical and non-clinical groups. A random effects model using a Fisher r-to-z transformed correlation coefficient was used for meta-analysis.

RESULTS

45 studies were included in the review and 14 in the meta-analysis. The literature supports a small-to-moderate association (r = 0.30, 95 % CI: 0.16-0.40 for the seven studies using the most robust measures) with significant heterogeneity among studies but no evidence of publication bias. There is evidence that the relationship is to some extent causal, with sleep disruption leading to increased paranoia, though there is also some evidence of a bi-directional relationship. Negative affect is frequently seen as a mediator of this relationship.

CONCLUSION

This review for the first time examines the significant relationship between sleep and paranoia individually. Studies are needed that further assess the potential for early intervention of sleep dysfunction in those experiencing paranoia.

Psychosis superspectrum I: Nosology, etiology, and lifespan development

This review describes the Hierarchical Taxonomy of Psychopathology (HiTOP) model of psychosis-related psychopathology, the psychosis superspectrum. The HiTOP psychosis superspectrum was developed to address shortcomings of traditional diagnoses for psychotic disorders and related conditions including low reliability, arbitrary boundaries between psychopathology and normality, high symptom co-occurrence, and heterogeneity within diagnostic categories. The psychosis superspectrum is a transdiagnostic dimensional model comprising two spectra-psychoticism and detachment-which are in turn broken down into fourteen narrow components, and two auxiliary domains-cognition and functional impairment. The structure of the spectra and their components are shown to parallel the genetic structure of psychosis and related traits. Psychoticism and detachment have distinct patterns of association with urbanicity, migrant and ethnic minority status, childhood adversity, and cannabis use. The superspectrum also provides a useful model for describing the emergence and course of psychosis, as components of the superspectrum are relatively stable over time. Changes in psychoticism predict the onset of psychosis-related psychopathology, whereas changes in detachment and cognition define later course. Implications of the superspectrum for genetic, socio-environmental, and longitudinal research are discussed. A companion review focuses on neurobiology, treatment response, and clinical utility of the superspectrum, and future research directions.