title: Sensory gating deficits in the attenuated psychosis syndrome.
abstract: BACKGROUND
  Individuals with an "Attenuated Psychosis Syndrome" (APS) have a 20-40% chance of developing a psychotic disorder within two years; however it is difficult to predict which of them will become ill on the basis of their clinical symptoms alone. We examined whether P50 gating deficits could help to discriminate individuals with APS and also those who are particularly likely to make a transition to psychosis.
  
  
  METHODS
  36 cases meeting PACE (Personal Assessment and Crisis Evaluation) criteria for the APS, all free of antipsychotics, and 60 controls performed an auditory conditioning-testing experiment while their electroencephalogram was recorded. The P50 ratio and its C-T difference were compared between groups. Subjects received follow-up for up to 2 years to determine their clinical outcome.
  
  
  RESULTS
  The P50 ratio was significantly higher and C-T difference lower in the APS group compared to controls. Of the individuals with APS who completed the follow-up (n=36), nine (25%) developed psychosis. P50 ratio and the C-T difference did not significantly differ between those individuals who developed psychosis and those who did not within the APS group.
  
  
  CONCLUSIONS
  P50 deficits appear to be associated with the pre-clinical phase of psychosis. However, due to the limitations of the study and its sample size, replication in an independent cohort is necessary, to clarify the role of P50 deficits in illness progression and whether this inexpensive and non-invasive EEG marker could be of clinical value in the prediction of psychosis outcomes amongst populations at risk.
authors.affiliation: NIHR Biomedical Research Centre for Mental Health at the Institute of Psychiatry, King's College London, The South London and Maudsley NHS Foundation Trust, London, UK; Department of Psychology, Royal Holloway, University of London, UK. Electronic address: Madiha.1.Shaikh@kcl.ac.uk.
authors.forename: Madiha
authors.initials: M
authors.lastname: Shaikh
authors.affiliation: NIHR Biomedical Research Centre for Mental Health at the Institute of Psychiatry, King's College London, The South London and Maudsley NHS Foundation Trust, London, UK.
authors.forename: Anirban
authors.initials: A
authors.lastname: Dutt
authors.affiliation: University of Warwick, Warwick Medical School, Coventry, UK.
authors.forename: Matthew R
authors.initials: MR
authors.lastname: Broome
authors.affiliation: Psychiatry Department, Hospital General Universitario Gregorio Marañón, Madrid, Spain.
authors.forename: Alberto G
authors.initials: AG
authors.lastname: Vozmediano
authors.affiliation: Division of Psychiatry & Institute of Cognitive Neuroscience, University College London, W1W 7EJ, UK.
authors.forename: Siri
authors.initials: S
authors.lastname: Ranlund
authors.affiliation: Division of Psychiatry & Institute of Cognitive Neuroscience, University College London, W1W 7EJ, UK.
authors.forename: Alvaro
authors.initials: A
authors.lastname: Diez
authors.affiliation: University Hospital Marqués de Valdecilla, IFIMAV, Spain.
authors.forename: Olalla
authors.initials: O
authors.lastname: Caseiro
authors.affiliation: NIHR Biomedical Research Centre for Mental Health at the Institute of Psychiatry, King's College London, The South London and Maudsley NHS Foundation Trust, London, UK.
authors.forename: Julia
authors.initials: J
authors.lastname: Lappin
authors.affiliation: NIHR Biomedical Research Centre for Mental Health at the Institute of Psychiatry, King's College London, The South London and Maudsley NHS Foundation Trust, London, UK.
authors.forename: Susan
authors.initials: S
authors.lastname: Amankwa
authors.affiliation: NIHR Biomedical Research Centre for Mental Health at the Institute of Psychiatry, King's College London, The South London and Maudsley NHS Foundation Trust, London, UK.
authors.forename: Francesco
authors.initials: F
authors.lastname: Carletti
authors.affiliation: NIHR Biomedical Research Centre for Mental Health at the Institute of Psychiatry, King's College London, The South London and Maudsley NHS Foundation Trust, London, UK.
authors.forename: Paolo
authors.initials: P
authors.lastname: Fusar-Poli
authors.affiliation: NIHR Biomedical Research Centre for Mental Health at the Institute of Psychiatry, King's College London, The South London and Maudsley NHS Foundation Trust, London, UK.
authors.forename: Muriel
authors.initials: M
authors.lastname: Walshe
authors.affiliation: Psychology Research Laboratory, Harvard Medical School, McLean Hospital, Belmont, MA, USA.
authors.forename: Mei-Hua
authors.initials: MH
authors.lastname: Hall
authors.affiliation: NIHR Biomedical Research Centre for Mental Health at the Institute of Psychiatry, King's College London, The South London and Maudsley NHS Foundation Trust, London, UK.
authors.forename: Oliver
authors.initials: O
authors.lastname: Howes
authors.affiliation: Department of Psychology, Royal Holloway, University of London, UK.
authors.forename: Lyn
authors.initials: L
authors.lastname: Ellett
authors.affiliation: NIHR Biomedical Research Centre for Mental Health at the Institute of Psychiatry, King's College London, The South London and Maudsley NHS Foundation Trust, London, UK.
authors.forename: Robin M
authors.initials: RM
authors.lastname: Murray
authors.affiliation: NIHR Biomedical Research Centre for Mental Health at the Institute of Psychiatry, King's College London, The South London and Maudsley NHS Foundation Trust, London, UK.
authors.forename: Philip
authors.initials: P
authors.lastname: McGuire
authors.affiliation: NIHR Biomedical Research Centre for Mental Health at the Institute of Psychiatry, King's College London, The South London and Maudsley NHS Foundation Trust, London, UK.
authors.forename: Lucia
authors.initials: L
authors.lastname: Valmaggia
authors.affiliation: NIHR Biomedical Research Centre for Mental Health at the Institute of Psychiatry, King's College London, The South London and Maudsley NHS Foundation Trust, London, UK; Division of Psychiatry & Institute of Cognitive Neuroscience, University College London, W1W 7EJ, UK.
authors.forename: Elvira
authors.initials: E
authors.lastname: Bramon
mesh_terms: D000161:Acoustic Stimulation; D000293:Adolescent; D000328:Adult; D004569:Electroencephalography; D005071:Evoked Potentials / Q000502:physiology; D005260:Female; D020233:Gait Disorders, Neurologic / Q000175:diagnosis* / Q000209:etiology*; D006801:Humans; D008297:Male; D011569:Psychiatric Status Rating Scales; D011618:Psychotic Disorders / Q000150:complications*; D012372:ROC Curve; D055139:Sensory Gating / Q000502:physiology*; D055815:Young Adult
keywords: APS; EEG; ERP; P50; Psychosis; Sensory-gating