title: Interacting mechanisms of impulsivity in bipolar disorder and antisocial personality disorder.
abstract: BACKGROUND
  Bipolar disorder and antisocial personality disorder (ASPD) overlap in clinical characteristics and behavioral consequences. Impulsivity is prominent in both, but there is little information on how specific mechanisms of impulsivity differentiate, bridge, or underlie the disorders.
  
  
  METHODS
  Subjects, all males, were controls (n = 46), bipolar disorder without cluster B personality disorder (n = 21), ASPD without bipolar disorder (n = 50), and bipolar disorder with ASPD (n = 16). Impulsivity measures were the Immediate Memory Task (IMT), a continuous performance test of response inhibition measuring ability to evaluate a stimulus before responding, and the Two-Choice Impulsivity Paradigm (TCIP), a choice between smaller-sooner and larger-later reward. Data were analyzed using general linear models analysis.
  
  
  RESULTS
  Subjects with bipolar disorder had fewer IMT correct detections and slower reaction times than controls. Reaction times were faster with combined diagnoses than in bipolar disorder alone. TCIP responding in either diagnosis alone resembled controls, but was more impulsive in combined disorders. These differences persisted after correction for age and education, which had significant independent effects. In combined ASPD and bipolar disorder, increased reaction speed, impulsive response bias, and reward-delay impulsivity occurred independent of substance-use disorder history.
  
  
  CONCLUSIONS
  Impulsivity was increased in the combined disorders over either disorder alone. Results were consistent with at least partially distinct mechanisms of impulsivity in ASPD and bipolar disorder. Compensatory mechanisms for impulsivity in uncomplicated ASPD or bipolar disorder appear to be compromised or lost when the disorders are combined.
authors: Department of Psychiatry and Behavioral Sciences, The University of Texas Health Science Center at Houston, BBSB, 1941 East Road, Room 3216, Houston, TX 77054, USA. Alan.C.Swann@uth.tmc.edu
authors: Alan C
authors: AC
authors: Swann
authors: Marijn
authors: M
authors: Lijffijt
authors: Scott D
authors: SD
authors: Lane
authors: Joel L
authors: JL
authors: Steinberg
authors: F Gerard
authors: FG
authors: Moeller
mesh_terms: D000328:Adult; D000987:Antisocial Personality Disorder / Q000523:psychology*; D001714:Bipolar Disorder / Q000523:psychology*; D015897:Comorbidity; D006801:Humans; D007175:Impulsive Behavior / Q000523:psychology*; D007266:Inhibition, Psychological; D008297:Male; D008570:Memory, Short-Term; D008875:Middle Aged; D009483:Neuropsychological Tests; D011569:Psychiatric Status Rating Scales; D011930:Reaction Time