title: Comorbid bipolar disorder and panic disorder in families with a high prevalence of bipolar disorder.
abstract: OBJECTIVE
  Panic attacks are a common complication of affective disorder, although the etiologic relationship of panic and affective symptoms has not been determined. Evidence from a family study suggests that panic attacks and panic disorder may be related genetically to bipolar disorder. This study used diagnostic data from the NIMH Bipolar Disorder Genetics Initiative to assess in a separate, larger family set the familiality of panic combined with bipolar disorder.
  
  
  METHODS
  First-degree relatives (N=966) of probands with bipolar I disorder (N=192) and schizoaffective disorder, bipolar type, (N=11) were included in the study. All subjects were interviewed directly and were assigned best-estimate diagnoses for major affective and other psychiatric disorders. The risk of a family member being diagnosed with panic disorder if the proband with bipolar disorder had panic attacks or panic disorder was calculated with logistic regression analysis with generalized estimating equations that controlled for sex and affective disorder subdiagnosis.
  
  
  RESULTS
  More than 90% of the probands and first-degree relatives with panic disorder also had an affective disorder diagnosis. Panic disorder was present in 17% of the relatives with recurrent major affective disorder and in 3% of the relatives without recurrent major affective disorder. Risk of panic disorder in relatives with bipolar disorder was increased significantly if the proband had panic attacks or panic disorder.
  
  
  CONCLUSIONS
  Risk for panic disorder with familial bipolar disorder appears to be inherited. Inherited risk for panic disorder with bipolar disorder may indicate a shared genetic etiology for both disorders in some families. The patterns of bipolar disorder and panic disorder comorbidity observed in families imply a complex genetic etiology, which may be elucidated by using endophenotypes.
authors.affiliation: Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA. dmackin@mail.jhmi.edu
authors.forename: Dean F
authors.initials: DF
authors.lastname: MacKinnon
authors.forename: Peter P
authors.initials: PP
authors.lastname: Zandi
authors.forename: Jennifer
authors.initials: J
authors.lastname: Cooper
authors.forename: James B
authors.initials: JB
authors.lastname: Potash
authors.forename: Sylvia G
authors.initials: SG
authors.lastname: Simpson
authors.forename: Elliot
authors.initials: E
authors.lastname: Gershon
authors.forename: John
authors.initials: J
authors.lastname: Nurnberger
authors.forename: Theodore
authors.initials: T
authors.lastname: Reich
authors.forename: J Raymond
authors.initials: JR
authors.lastname: DePaulo
mesh_terms: D000328:Adult; D001714:Bipolar Disorder / Q000150:complications / Q000175:diagnosis / Q000235:genetics*; D015897:Comorbidity; D005260:Female; D020022:Genetic Predisposition to Disease / Q000235:genetics; D006801:Humans; D008297:Male; D008875:Middle Aged; D016584:Panic Disorder / Q000150:complications / Q000175:diagnosis / Q000235:genetics*; D010641:Phenotype; D011569:Psychiatric Status Rating Scales