Shared Etiology of Psychotic Experiences and Depressive Symptoms in Adolescence: A Longitudinal Twin Study.

Helena M S Zavos,Thalia C Eley,Robert Plomin,Angelica Ronald,Daniel Freeman,Alastair G Cardno,Philip Mcguire

doi:10.1093/schbul/sbw021

Abstract

Psychotic disorders and major depression, both typically adult-onset conditions, often co-occur. At younger ages psychotic experiences and depressive symptoms are often reported in the community. We used a genetically sensitive longitudinal design to investigate the relationship between psychotic experiences and depressive symptoms in adolescence. A representative community sample of twins from England and Wales was employed. Self-rated depressive symptoms, paranoia, hallucinations, cognitive disorganization, grandiosity, anhedonia, and parent-rated negative symptoms were collected when the twins were age 16 (N = 9618) and again on a representative subsample 9 months later (N = 2873). Direction and aetiology of associations were assessed using genetically informative cross-lagged models. Depressive symptoms were moderately correlated with paranoia, hallucinations, and cognitive disorganization. Lower correlations were observed between depression and anhedonia, and depression and parent-rated negative symptoms. Nonsignificant correlations were observed between depression and grandiosity. Largely the same genetic effects influenced depression and paranoia, depression and hallucinations, and depression and cognitive disorganization. Modest overlap in environmental influences also played a role in the associations. Significant bi-directional longitudinal associations were observed between depression and paranoia. Hallucinations and cognitive disorganization during adolescence were found to impact later depression, even after controlling for earlier levels of depression. Our study shows that psychotic experiences and depression, as traits in the community, have a high genetic overlap in mid-adolescence. Future research should test the prediction stemming from our longitudinal results, namely that reducing or ameliorating positive and cognitive psychotic experiences in adolescence would decrease later depressive symptoms.

Highlights

Identifying those at high risk of psychosis is an important part of early clinical intervention in mental health.[1]
The Longitudinal Experiences And Perceptions (LEAP) study assessed psychotic experiences in adolescents[3] drawn from the Twins Early Development Study (TEDS), a general population sample of monozygotic (MZ) and dizygotic (DZ) twins born in England and Wales between 1994– 1996.3 TEDS was approved by the Institute of Psychiatry ethics committee
Families were not contacted for the LEAP study if they had withdrawn from TEDS, had never returned any data, had known address problems, or were special cases, most notably medical exclusions

Summary

Introduction

Identifying those at high risk of psychosis is an important part of early clinical intervention in mental health.[1] One area of study has focused on psychotic experiences which are present in the general population in adolescence.[2,3] Psychotic experiences in adolescence have been shown to be associated with elevated rates of prodromal syndromes[2] and increased risk of psychosis in later life[4] another study did not find an association with psychotic disorders at age 18 years.[5] The presentation of psychosis is heterogeneous, including positive (eg, hallucinations) and negative (eg, lack of affect) symptoms. In the only study to explore bidirectional effects between psychotic experiences and depression in adolescence, psychotic experiences at 12 years old predicted depression at 18 years old to a greater extent than depression at 12 years old predicted psychotic experiences at 18 years old.[14]

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