title: Could comorbid bipolar disorder account for a significant share of executive function deficits in adults with attention-deficit hyperactivity disorder?
abstract: OBJECTIVE
  The frequent comorbidity between attention-deficit hyperactivity disorder (ADHD) and bipolar disorder (BD) represents a challenge for disentangling specific impairments of each disorder in adulthood. Their functional impairments seem to be mediated by executive function deficits. However, little is known about the extent to which each executive function deficit might be disorder specific or explained by the comorbidity. The aim of the present study was to determine if comorbid BD could account for a significant share of executive function deficits when measured by the Wisconsin Card Sorting Test (WCST) in adults with ADHD.
  
  
  METHODS
  Adult patients with ADHD and healthy subjects were evaluated in the ADHD outpatient Program at the Hospital de Clínicas de Porto Alegre. Psychiatric diagnoses were based on DSM-IV criteria. WCST scores were compared by multivariate analysis of covariance among three groups: ADHD with BD (n = 51), ADHD without BD (n = 278), and healthy subjects (n = 91).
  
  
  RESULTS
  When compared to patients without BD and healthy subjects, patients with ADHD and comorbid BD showed lower scores in total correct answers (p = 0.003); higher scores in total errors (p = 0.004) and non-perseverative errors (p = 0.002); and completed fewer categories (p = 0.009). Patients with ADHD without BD did not differ from healthy subjects.
  
  
  CONCLUSIONS
  WCST impairments among patients with ADHD seem to be to a large extent attributable to comorbid BD. Although other executive function deficits (e.g., in the inhibitory control domain) have been demonstrated to accompany ADHD, the present findings suggest that set-shifting deficits are strongly related to comorbid BD.
authors.affiliation: ADHD Outpatient Program-Adult Division, Hospital de Clínicas de Porto Alegre, Porto Alegre, RS, Brazil.
authors.forename: Katiane L
authors.initials: KL
authors.lastname: Silva
authors.forename: Diego L
authors.initials: DL
authors.lastname: Rovaris
authors.forename: Paula O
authors.initials: PO
authors.lastname: Guimarães-da-Silva
authors.forename: Marcelo M
authors.initials: MM
authors.lastname: Victor
authors.forename: Carlos A I
authors.initials: CA
authors.lastname: Salgado
authors.forename: Eduardo S
authors.initials: ES
authors.lastname: Vitola
authors.forename: Verônica
authors.initials: V
authors.lastname: Contini
authors.forename: Guilherme
authors.initials: G
authors.lastname: Bertuzzi
authors.forename: Felipe A
authors.initials: FA
authors.lastname: Picon
authors.forename: Rafael G
authors.initials: RG
authors.lastname: Karam
authors.forename: Paulo
authors.initials: P
authors.lastname: Belmonte-de-Abreu
authors.forename: Luis A
authors.initials: LA
authors.lastname: Rohde
authors.forename: Eugenio H
authors.initials: EH
authors.lastname: Grevet
authors.forename: Claiton H D
authors.initials: CH
authors.lastname: Bau
mesh_terms: D000328:Adult; D001289:Attention Deficit Disorder with Hyperactivity / Q000150:complications* / Q000453:epidemiology; D001714:Bipolar Disorder / Q000150:complications* / Q000453:epidemiology; D003072:Cognition Disorders / Q000209:etiology*; D056344:Executive Function / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D009483:Neuropsychological Tests; D011569:Psychiatric Status Rating Scales; D055815:Young Adult
keywords: ADHD; Wisconsin Card Sorting Test; attention-deficit hyperactivity disorder; bipolar disorder; executive function