title: The prevalence and illness characteristics of DSM-5-defined "mixed feature specifier" in adults with major depressive disorder and bipolar disorder: Results from the International Mood Disorders Collaborative Project.
abstract: BACKGROUND
  A substantial proportion of individuals with mood disorders present with sub-syndromal hypo/manic features. The objective of this analysis was to evaluate the prevalence and illness characteristics of the Diagnostic and Statistical Manual Version-5 (DSM-5) - defined mixed features specifier (MFS) in adults with major depressive disorder (MDD) and bipolar disorder (BD).
  
  
  METHODS
  Data from participants who met criteria for a current mood episode as part of MDD (n=506) or BD (BD-I: n=216, BD-II: n=130) were included in this post-hoc analysis. All participants were enrolled in the International Mood Disorders Collaborative Project (IMDCP): a collaborative research platform at the Mood Disorders Psychopharmacology Unit, University of Toronto and the Cleveland Clinic, Cleveland, Ohio. Mixed features specifier was operationalized as a score ≥ 1 on 3 or more select items on the Young Mania Rating Scale (YMRS) or ≥ 1 on 3 select items of the Montgomery Åsberg Depression Rating Scale (MADRS) or Hamilton Depression Rating Scale (HAMD-17) during an index major depressive episode (MDE) or hypo/manic episode, respectively.
  
  
  RESULTS
  A total of 26.0% (n=149), 34.0% (n=65), and 33.8% (n=49) of individuals met criteria for MFS during an index MDE as part of MDD, BD-I and BD-II, respectively. Mixed features specifier during a hypo/manic episode was identified in 20.4% (n=52) and 5.1% (n=8) in BD-I and BD-II participants, respectively. Individuals with MDE-MFS as part of BD or MDD exhibited a more severe depressive phenotype (p=0.0002 and p<0.0002, respectively) and reported a higher rate of alcohol/substance use disorder in the context of BD but not MDD (p=0.002). Individuals with MFS were more likely to have co-existing heart disease suggestive of a distinct pattern of comorbidity and neurobiology.
  
  
  CONCLUSIONS
  Data were post-hoc and obtained from individuals utilizing a university-based mood disorder centre which may affect generalizability.
  
  
  CONCLUSIONS
  Diagnostic and Statistical Manual Version-5-defined MFS is common during an MDE as part of MDD and BD. The presence of MFS identifies a subgroup of individuals with greater illness complexity and possibly a higher rate of cardiovascular comorbidity. The results herein underscore the common occurrence of MFS in adults with either BD or MDD. Moreover, the results of our analysis indicate that adults with mood disorders and MFS have distinct clinical characteristics and comorbidity patterns.
authors.affiliation: Department of Psychiatry, University of Toronto, Toronto, ON, Canada; Department of Pharmacology, University of Toronto, Toronto, ON, Canada; Mood Disorders Psychopharmacology Unit, University Health Network, Toronto, ON, Canada; Institute of Medical Science, University of Toronto, Toronto, ON, Canada. Electronic address: Roger.McIntyre@uhn.ca.
authors.forename: Roger S
authors.initials: RS
authors.lastname: McIntyre
authors.affiliation: Mood Disorders Psychopharmacology Unit, University Health Network, Toronto, ON, Canada; Institute of Medical Science, University of Toronto, Toronto, ON, Canada.
authors.forename: Joanna K
authors.initials: JK
authors.lastname: Soczynska
authors.affiliation: Mood Disorders Psychopharmacology Unit, University Health Network, Toronto, ON, Canada; Institute of Medical Science, University of Toronto, Toronto, ON, Canada.
authors.forename: Danielle S
authors.initials: DS
authors.lastname: Cha
authors.affiliation: Mood Disorders Psychopharmacology Unit, University Health Network, Toronto, ON, Canada.
authors.forename: Hanna O
authors.initials: HO
authors.lastname: Woldeyohannes
authors.affiliation: Cleveland Clinic, Cleveland, OH, USA.
authors.forename: Roman S
authors.initials: RS
authors.lastname: Dale
authors.affiliation: Mood Disorders Psychopharmacology Unit, University Health Network, Toronto, ON, Canada.
authors.forename: Mohammad T
authors.initials: MT
authors.lastname: Alsuwaidan
authors.affiliation: Mood Disorders Psychopharmacology Unit, University Health Network, Toronto, ON, Canada.
authors.forename: Laura Ashley
authors.initials: LA
authors.lastname: Gallaugher
authors.affiliation: Mood Disorders Psychopharmacology Unit, University Health Network, Toronto, ON, Canada.
authors.forename: Rodrigo B
authors.initials: RB
authors.lastname: Mansur
authors.affiliation: Medco Health Solutions, Inc, Fort Worth, TX, USA.
authors.forename: David J
authors.initials: DJ
authors.lastname: Muzina
authors.affiliation: Translational Psychiatry Research Group and Department of Clinical Medicine, Faculty of Medicine, Federal University of Ceara, Fortaleza, Brazil.
authors.forename: Andre
authors.initials: A
authors.lastname: Carvalho
authors.affiliation: Department of Psychiatry, University of Toronto, Toronto, ON, Canada; Institute of Medical Science, University of Toronto, Toronto, ON, Canada.
authors.forename: Sidney H
authors.initials: SH
authors.lastname: Kennedy
mesh_terms: D000328:Adult; D000339:Affect; D001714:Bipolar Disorder / Q000175:diagnosis* / Q000453:epidemiology; D015897:Comorbidity; D003865:Major Depressive Disorder / Q000175:diagnosis* / Q000453:epidemiology; D039721:Diagnostic and Statistical Manual of Mental Disorders; D005260:Female; D006801:Humans; D008297:Male; D019964:Mood Disorders / Q000175:diagnosis* / Q000453:epidemiology; D015995:Prevalence; D011569:Psychiatric Status Rating Scales; D055815:Young Adult
keywords: Bipolar disorder; DSM-5; Mixed states