title: Longitudinal associations between adolescent psychotic experiences and depressive symptoms.
abstract: BACKGROUND
  Psychotic experiences are prevalent in community samples and are highly correlated with depressive symptoms. This study aimed to investigate the longitudinal associations between psychotic experiences and depressive symptoms between adolescence and young adulthood.
  
  
  METHODS
  Prospective cohort study with a 6 year follow-up in a community sample of 7632 adolescents and young adults. Depressive symptoms were assessed with the Short Moods and Feelings Questionnaire and psychotic experiences with a semi-structured clinical interview at 12 and 18 years. Longitudinal and cross-sectional associations were investigated with regression and structural equation models.
  
  
  RESULTS
  Depressive symptoms and psychotic experiences were associated at each time-point (12 years r = 0.486 [95% CI 0.457, 0.515]; 18 years r = 0.286 [95% CI 0.233, 0.339]) and there were longitudinal within-phenotype associations (depressive symptoms r = 0.252 [95% CI 0.205, 0.299]; psychotic experiences r = 0.662 [95% CI 0.595, 0.729]). There was an across-phenotype association between psychotic experiences at 12 and depressive symptoms at 18 r = 0.139 [95% CI 0.086, 0.192; p<0.001], but no association between depressive symptoms at 12 and psychotic experiences at 18 r = -0.022 [95% CI -0.032, 0.077; p = 0.891].
  
  
  CONCLUSIONS
  Longitudinal across-phenotype associations were substantially weaker than cross-sectional associations or within-phenotype longitudinal associations. Whilst psychotic experiences at 12 years were associated with a small increase in depression at 18 years, depression at 12 years was not associated with psychotic experiences at 18 years once across-phenotype cross-sectional and within-phenotype longitudinal associations were accounted for. This suggests that the biological mechanisms underlying depression at this age do not increase subsequent risk of psychotic experiences once they resolve.
authors.affiliation: Centre for Academic Mental Health, School of Social and Community Medicine, University of Bristol, Bristol, United Kingdom.
authors.forename: Sarah A
authors.initials: SA
authors.lastname: Sullivan
authors.affiliation: Centre for Academic Mental Health, School of Social and Community Medicine, University of Bristol, Bristol, United Kingdom.
authors.forename: Nicola
authors.initials: N
authors.lastname: Wiles
authors.affiliation: Centre for Academic Mental Health, School of Social and Community Medicine, University of Bristol, Bristol, United Kingdom.
authors.forename: Daphne
authors.initials: D
authors.lastname: Kounali
authors.affiliation: Division of Psychiatry, University College London, London, United Kingdom.
authors.forename: Glyn
authors.initials: G
authors.lastname: Lewis
authors.affiliation: Centre for Academic Mental Health, School of Social and Community Medicine, University of Bristol, Bristol, United Kingdom.
authors.forename: Jon
authors.initials: J
authors.lastname: Heron
authors.affiliation: Department of Psychiatry, Royal College of Surgeons in Ireland, Dublin, Ireland.
authors.forename: Mary
authors.initials: M
authors.lastname: Cannon
authors.affiliation: Centre for Academic Mental Health, School of Social and Community Medicine, University of Bristol, Bristol, United Kingdom.
authors.forename: Liam
authors.initials: L
authors.lastname: Mahedy
authors.affiliation: Department of Psychiatry, Cambridge Neuroscience, University of Cambridge, Cambridge, United Kingdom.
authors.forename: Peter B
authors.initials: PB
authors.lastname: Jones
authors.affiliation: Department of Psychiatry, Cambridge Neuroscience, University of Cambridge, Cambridge, United Kingdom.
authors.forename: Jan
authors.initials: J
authors.lastname: Stochl
authors.affiliation: Centre for Academic Mental Health, School of Social and Community Medicine, University of Bristol, Bristol, United Kingdom; Institute of Psychological Medicine and Clinical Neurosciences, University of Cardiff, Cardiff, United Kingdom.
authors.forename: Stan
authors.initials: S
authors.lastname: Zammit
mesh_terms: D000293:Adolescent; D002648:Child; D003863:Depression / Q000150:complications* / Q000453:epidemiology / Q000503:physiopathology / Q000523:psychology; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D010641:Phenotype; D011446:Prospective Studies; D011618:Psychotic Disorders / Q000150:complications* / Q000453:epidemiology / Q000503:physiopathology / Q000523:psychology; D012044:Regression Analysis; D011795:Surveys and Questionnaires; D006113:United Kingdom / Q000453:epidemiology