title: Functional connectivity and temporal variability of brain connections in adults with attention deficit/hyperactivity disorder and bipolar disorder.
abstract: OBJECTIVE
  To assess brain functional connectivity and variability in adults with attention deficit/hyperactivity disorder (ADHD) or euthymic bipolar disorder (BD) relative to a control (CT) group.
  
  
  METHODS
  Electroencephalography (EEG) was measured in 35 participants (BD = 11; ADHD = 9; CT = 15) during an eyes-closed 10-min rest period, and connectivity and graph theory metrics were computed. A coefficient of variation (CV) computed also the connectivity's temporal variability of EEG. Multivariate associations between functional connectivity and clinical and neuropsychological profiles were evaluated.
  
  
  RESULTS
  An enhancement of functional connectivity was observed in the ADHD (fronto-occipital connections) and BD (diffuse connections) groups. However, compared with CTs, intrinsic variability (CV) was enhanced in the ADHD group and reduced in the BD group. Graph theory metrics confirmed the existence of several abnormal network features in both affected groups. Significant associations of connectivity with symptoms were also observed. In the ADHD group, temporal variability of functional connections was associated with executive function and memory deficits. Depression, hyperactivity and impulsivity levels in the ADHD group were associated with abnormal intrinsic connectivity. In the BD group, levels of anxiety and depression were related to abnormal frontotemporal connectivity.
  
  
  CONCLUSIONS
  In the ADHD group, we found that intrinsic variability was associated with deficits in cognitive performance and that connectivity abnormalities were related to ADHD symptomatology. The BD group exhibited less intrinsic variability and more diffuse long-range brain connections, and those abnormalities were related to interindividual differences in depression and anxiety. These preliminary results are relevant for neurocognitive models of abnormal brain connectivity in both disorders.
authors.affiliation: Laboratory of Experimental Psychology and Neuroscience, Institute of Cognitive Neurology, Favaloro University, Buenos Aires, Argentina.
authors.forename: Pablo
authors.initials: P
authors.lastname: Barttfeld
authors.forename: Agustín
authors.initials: A
authors.lastname: Petroni
authors.forename: Sandra
authors.initials: S
authors.lastname: Báez
authors.forename: Hugo
authors.initials: H
authors.lastname: Urquina
authors.forename: Mariano
authors.initials: M
authors.lastname: Sigman
authors.forename: Marcelo
authors.initials: M
authors.lastname: Cetkovich
authors.forename: Teresa
authors.initials: T
authors.lastname: Torralva
authors.forename: Fernando
authors.initials: F
authors.lastname: Torrente
authors.forename: Alicia
authors.initials: A
authors.lastname: Lischinsky
authors.forename: Xavier
authors.initials: X
authors.lastname: Castellanos
authors.forename: Facundo
authors.initials: F
authors.lastname: Manes
authors.forename: Agustín
authors.initials: A
authors.lastname: Ibañez
mesh_terms: D000328:Adult; D001007:Anxiety / Q000503:physiopathology; D001289:Attention Deficit Disorder with Hyperactivity / Q000503:physiopathology* / Q000523:psychology*; D001714:Bipolar Disorder / Q000503:physiopathology* / Q000523:psychology*; D001921:Brain / Q000503:physiopathology*; D003072:Cognition Disorders / Q000503:physiopathology; D003863:Depression / Q000503:physiopathology; D004569:Electroencephalography; D006801:Humans; D007175:Impulsive Behavior / Q000502:physiology; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D009434:Neural Pathways / Q000503:physiopathology; D009483:Neuropsychological Tests; D012146:Rest; D013997:Time Factors