title: Longitudinal course and characteristics of cyclothymic disorder in youth.
abstract: Epidemiological studies suggest that cyclothymic disorder is the most prevalent subtype of bipolar disorder (BD). However, it is rarely diagnosed, especially in youth. This may be because it can be difficult to ascertain whether a youth meets diagnostic criteria. Clearer, easy-to-apply criteria could reduce misdiagnosis. The objective oftable this study was to determine whether proposed research diagnostic criteria for cyclothymic disorder (RDCyc), based on DSM-5 criteria, could be quantified and validated in youth.
  
  
  
  Participants from the Longitudinal Assessment of Manic Symptoms (LAMS) study were recruited based on symptoms of mania and followed prospectively. RDCyc criteria were: 1) At least one core symptom each of mania and depression; 2) one additional symptom of mania and of depression; 3) persistence over two consecutive six-month periods, and 4) impairment. Exclusionary criteria were having a [hypo]manic or depressive episode. Outcomes at the two-year follow-up were compared between RDCyc youth and other diagnostic groups (BD I/II, BD NOS/non-RDCyc cyclothymic disorder, disruptive behavior disorders [DBD], depression).
  
  
  
  Thirty-seven youth met RDCyc criteria. There were no consistent differences between the RDCyc youth and youth with other BD subtypes (ps=0.001-0.960, with all-but-one p value >0.02). RDCyc youth had higher depression (p<0.0005) and mania scores (p=0.001), lower functioning (p=0.012), and higher suicide risk than DBD youth (p=0.001). They had higher mania scores than depressed youth (p.018).
  
  
  
  The majority of youth in the sample were recruited due to elevated symptoms of mania, which may limit the generalizability of the results. Youth were followed for two years, which may not be long enough to determine whether or not they will eventually develop a manic or depressive episode.
  
  
  
  Applying RDCyc criteria identified youth who were similar to others with BD and were more impaired than those with DBD. Using these criteria could reduce misdiagnosis and increase our understanding of this prevalent, but largely ignored, diagnosis.
authors.affiliation: Yeshiva University, USA. Electronic address: Anna.vanmeter@einstein.yu.edu.
authors.forename: Anna R
authors.initials: AR
authors.lastname: Van Meter
authors.affiliation: University of North Carolina at Chapel Hill, USA.
authors.forename: Eric A
authors.initials: EA
authors.lastname: Youngstrom
authors.affiliation: University of Pittsburgh, USA.
authors.forename: Boris
authors.initials: B
authors.lastname: Birmaher
authors.affiliation: The Ohio State University, USA.
authors.forename: Mary A
authors.initials: MA
authors.lastname: Fristad
authors.affiliation: New York University, USA.
authors.forename: Sarah M
authors.initials: SM
authors.lastname: Horwitz
authors.affiliation: Cleveland Clinic Lerner College of Medicine, USA.
authors.forename: Thomas W
authors.initials: TW
authors.lastname: Frazier
authors.affiliation: The Ohio State University, USA.
authors.forename: L Eugene
authors.initials: LE
authors.lastname: Arnold
authors.affiliation: Johns Hopkins University/Kennedy Krieger Institute, USA.
authors.forename: Robert L
authors.initials: RL
authors.lastname: Findling
mesh_terms: D001714:Bipolar Disorder / Q000175:diagnosis / Q000453:epidemiology / Q000523:psychology; D002648:Child; D003527:Cyclothymic Disorder / Q000175:diagnosis / Q000453:epidemiology / Q000523:psychology*; D003863:Depression / Q000175:diagnosis / Q000523:psychology; D039721:Diagnostic and Statistical Manual of Mental Disorders; D018450:Disease Progression; D005190:Family; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D009483:Neuropsychological Tests; D011446:Prospective Studies; D011619:Psychotropic Drugs / Q000627:therapeutic use; D015203:Reproducibility of Results; D013405:Suicide / Q000706:statistics & numerical data; D016896:Treatment Outcome
chemical_list: D011619:Psychotropic Drugs
keywords: Cyclothymic disorder; Diagnosis; Longitudinal; Youth