title: A systematic review of cognitive function in first-episode psychosis, including a discussion on childhood trauma, stress, and inflammation.
abstract: OBJECTIVE
  To carry out a systematic review of the literature addressing cognitive functions in first-episode psychosis (FEP), divided into domains. Although this is not a full "cognitive-genetics-in-schizophrenia review," we will also include putative ideas of mechanism(s) behind these impairments, focusing on how early stress, and genetic vulnerability may moderate cognitive function in psychosis.
  
  
  METHODS
  Relevant studies were identified via computer literature searches for research published up to and including January 2013, only case-control studies were included for the neurocognitive meta-analysis.
  
  
  RESULTS
  Patients with FEP present global cognitive impairment compared to healthy controls. The largest effect size was observed for verbal memory (Cohen's d effect size = 2.10), followed by executive function (effect size = 1.86), and general IQ (effect size = 1.71). However, effect sizes varied between studies.
  
  
  CONCLUSIONS
  Cognitive impairment across domains, up to severe level based on Cohen's effect size, is present already in FEP studies. However, differences in levels of impairment are observed between studies, as well as within domains, indicating that further consolidation of cognitive impairment over the course of illness may be present. Cognitive abnormalities may be linked to a neurodevelopmental model including increased sensitivity to the negative effect of stress, as well as genetic vulnerability. More research on this field is needed.
authors.affiliation: Division of Mental Health and Addiction, Institute of Clinical Medicine, University of Oslo , Oslo , Norway ; NORMENT, K.G. Jebsen Psychosis Research Unit, Division of Mental Health and Addiction, Oslo University Hospital , Oslo , Norway.
authors.forename: Monica
authors.initials: M
authors.lastname: Aas
authors.affiliation: Department of Psychosis Studies, Institute of Psychiatry, King's College London , London , UK ; NIHR Biomedical Research Centre for Mental Health, South London and Maudsley NHS Foundation Trust and Institute of Psychiatry, King's College London , London , UK.
authors.forename: Paola
authors.initials: P
authors.lastname: Dazzan
authors.affiliation: Department of Psychological Medicine, Institute of Psychiatry, King's College London , London , UK.
authors.forename: Valeria
authors.initials: V
authors.lastname: Mondelli
authors.affiliation: Division of Mental Health and Addiction, Institute of Clinical Medicine, University of Oslo , Oslo , Norway ; NORMENT, K.G. Jebsen Psychosis Research Unit, Division of Mental Health and Addiction, Oslo University Hospital , Oslo , Norway.
authors.forename: Ingrid
authors.initials: I
authors.lastname: Melle
authors.affiliation: Department of Psychosis Studies, Institute of Psychiatry, King's College London , London , UK ; NIHR Biomedical Research Centre for Mental Health, South London and Maudsley NHS Foundation Trust and Institute of Psychiatry, King's College London , London , UK.
authors.forename: Robin M
authors.initials: RM
authors.lastname: Murray
authors.affiliation: NIHR Biomedical Research Centre for Mental Health, South London and Maudsley NHS Foundation Trust and Institute of Psychiatry, King's College London , London , UK ; Department of Psychological Medicine, Institute of Psychiatry, King's College London , London , UK.
authors.forename: Carmine M
authors.initials: CM
authors.lastname: Pariante
keywords: cognition; first-episode psychosis; genes × environment interactions; physiological; review of literature; stress