title: Biological aspects and candidate biomarkers for psychotic bipolar disorder: A systematic review.
abstract: OBJECTIVE
  We carried out a systematic review of the available literature about potential biomarkers of psychotic bipolar disorder (BD-P), a specific subset presenting worse outcome and greater risk of relapse than non-psychotic bipolar disorder (BD-NP).
  
  
  METHODS
  We searched the main psychiatric databases (PubMed, ISI Web of Knowledge, PsychInfo). Only original articles with the main topic of BD-P compared to schizophrenia/BD-NP/healthy controls (HC) written in English from 1994 to 2015 were included.
  
  
  RESULTS
  BD-P patients presented higher kynurenic acid levels in the cerebrospinal fluid, elevated anti- S accharomyces cerevisiae antibodies levels, and lower serum levels of dehydroepiandrosterone sulfate and progesterone than BD-NP/HC. Event-related potentials abnormalities have been identified in BD-P with respect to BD-NP. BD-P patients also presented bigger ventricles but similar hippocampal volumes compared to BD-NP/HC. Although the results are contrasting, some cognitive deficits seemed to be related to the psychotic dimension of bipolar affective disorder, such as impairment in verbal/logical memory, working memory, verbal and semantic fluency and executive functioning. Finally, polymorphisms of genes, such as NRG1, 5HTTLPR (s), COMT, DAOA and some chromosome regions (16p12 and 13q), were positively associated with BD-P.
  
  
  CONCLUSIONS
  Data about the identification of specific biomarkers for BD-P are promising, but most of them have not yet been replicated. They could lead the clinicians to an early diagnosis and proper treatment, thus ameliorating outcome of BD-P and reducing the biological changes associated with a long duration of illness. Further studies with bigger samples are needed to detect more specific biological markers of the psychotic dimension of bipolar affective disorder.
authors.affiliation: Department of Psychiatry, University of Milan, Fondazione IRCCS Ca' Granda, Ospedale Maggiore Policlinico, Milan, Italy.|Department of Psychiatry, University Medical Center Utrecht - Brain Centre Rudolf Magnus, Utrecht, The Netherlands.
authors.forename: Massimiliano
authors.initials: M
authors.lastname: Buoli
authors.affiliation: Department of Psychiatry, University of Milan, Fondazione IRCCS Ca' Granda, Ospedale Maggiore Policlinico, Milan, Italy.
authors.forename: Alice
authors.initials: A
authors.lastname: Caldiroli
authors.affiliation: Department of Psychiatry, University of Milan, Fondazione IRCCS Ca' Granda, Ospedale Maggiore Policlinico, Milan, Italy.
authors.forename: Claudia
authors.initials: C
authors.lastname: Cumerlato Melter
authors.affiliation: Department of Psychiatry, University of Milan, Fondazione IRCCS Ca' Granda, Ospedale Maggiore Policlinico, Milan, Italy.
authors.forename: Marta
authors.initials: M
authors.lastname: Serati
authors.affiliation: Department of Psychiatry, University Medical Center Utrecht - Brain Centre Rudolf Magnus, Utrecht, The Netherlands.
authors.forename: Jessica
authors.initials: J
authors.lastname: de Nijs
authors.affiliation: Department of Psychiatry, University of Milan, Fondazione IRCCS Ca' Granda, Ospedale Maggiore Policlinico, Milan, Italy.
authors.forename: A Carlo
authors.initials: AC
authors.lastname: Altamura
mesh_terms: D015415:Biomarkers; D001714:Bipolar Disorder / Q000175:diagnosis*; D006801:Humans
chemical_list: D015415:Biomarkers
keywords: biomarkers; bipolar disorder; psychoneurobiology; psychopathology; psychotic symptoms