Chronotype and psychopathology: insights from a genetically informative design

Abstract

STUDY OBJECTIVES: Chronotype has been linked to a wide variety of psychiatric conditions. In particular, evening chronotype could be a transdiagnostic risk factor for different mental health difficulties. In this study, we examine how chronotype relates to psychopathology and whether it can be conceptualized as a part of the global construct of psychopathology (p-factor) by studying the genetic and environmental overlap between these variables. We utilize data from a genetically informative design to study: (1) the association between chronotype and psychopathology; (2) the genetic and environmental overlap between chronotype and psychopathology; and (3) the predictive value of polygenic score (PGS) for chronotype for psychopathology. METHODS: Chronotype was measured using an abbreviated version of the Munich Chronotype Questionnaire. Measures of psychopathology included: depression, anxiety, alcohol use, and psychotic experiences among others. We used different psychopathology and chronotype-related polygenic scores. Association between chronotype and psychopathology were examined with three approaches: (1) phenotypic associations; (2) genetic and environmental associations using the twin design; and (3) genetic associations using PGS. RESULTS: There were small, though largely significant, associations between chronotype and psychopathology with significant genetic and environmental overlap. Chronotype PGS significantly predicted a very small proportion of the variance for some measures of psychopathology (e.g. symptoms of attention deficit hyperactivity disorder). However, overall, our results also suggest that the majority of genetic/environmental influences (96 per cent) on chronotype do not overlap with those on the psychopathology factor. CONCLUSIONS: Results from this study highlight existence of significant associations between chronotype and certain psychopathology traits. However, the very small associations do not support the idea that chronotype is a core element of the general "p-factor."