title: Cortical functional activity in patients with generalized anxiety disorder.
abstract: The neurological correlates of Generalised Anxiety Disorder (GAD) are not well known, however there is evidence of cortical dysregulation in patients with GAD. The aim of the study was to examine cortical functional activity in different cerebral regions in patients with GAD using electroencephalogram (EEG) nonlinear analysis to evaluate its contribution of anxiety severity.
  
  
  
  The cohorts consisted of 64 patients diagnosed with GAD as classified by the Structured Clinical Interview for the Diagnostic and Statistical Manual of the American Psychiatric Association-IV-TR. Anxiety severity was assessed using the Hamilton Rating Scale for Anxiety (HAMA) severity score, with 7 ≤ scores ≤ 17 indicating mild anxiety as A group (n = 31) and 18 and above indicating moderate-severe anxiety as B group (n = 33). Participants with clinical levels of depression symptoms were excluded. A healthy control group comprising 30 participants was matched for age and gender. Closed eyes EEGs were conducted, and between-group differences on non-linear parameter Correlation Dimension (D2) were analyzed. The association of D2 value with HAMA scores was analyzed using multiple linear stepwise regression.
  
  
  
  Compared with the control group, D2 values were increased in anxiety groups (P < .05). For those with mild anxiety, this difference occurred in the left prefrontal regions (P < .05). For those with moderate-severe anxiety, significantly greater D2 values were observed in all of the cerebral regions, especially in the left cerebral regions and right temporal lobe (P < .01). When compared with those with mild anxiety, D2 values were significantly greater for those with moderate-severe anxiety in the right temporal lobe and all left cerebral regions except for left occipital lobe (P < .05). A positive correlation was observed between D2 values and moderate-severe anxiety HAMA scores.
  
  
  
  The increased D2 values were found in the majority of cerebral regions in GAD patients, especially in the left cerebral regions and the right temporal lobe. The increased GAD severity positively correlates to the D2 values in a larger number of cerebral regions. This analysis method can potentially be used as a complementary tool to examine dysfunctional cortical activity in GAD.
authors.affiliation: Department of Psychiatry, Affiliated Hospital of Guizhou Medical University, Guiyang, Guizhou, 550004, China. yimingw66@yahoo.com.
authors.forename: Yiming
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Department of Psychiatry, Affiliated Hospital of Guizhou Medical University, Guiyang, Guizhou, 550004, China.
authors.forename: Fangxian
authors.initials: F
authors.lastname: Chai
authors.affiliation: Department of Cardiolog, The General Hospital of Jinan Military Region, Jinan, 250031, China.
authors.forename: Hongming
authors.initials: H
authors.lastname: Zhang
authors.affiliation: Department of Cardiolog, Affiliated Hospital of Guizhou Medical University, Guiyang, Guizhou, 550004, China. lxd@gmc.edu.cn.
authors.forename: Xingde
authors.initials: X
authors.lastname: Liu
authors.affiliation: Department of Psychiatry, Affiliated Hospital of Guizhou Medical University, Guiyang, Guizhou, 550004, China.
authors.forename: Pingxia
authors.initials: P
authors.lastname: Xie
authors.affiliation: Department of Psychiatry, Affiliated Hospital of Guizhou Medical University, Guiyang, Guizhou, 550004, China.
authors.forename: Lei
authors.initials: L
authors.lastname: Zheng
authors.affiliation: Department of Psychiatry, Affiliated Hospital of Guizhou Medical University, Guiyang, Guizhou, 550004, China.
authors.forename: Lixia
authors.initials: L
authors.lastname: Yang
authors.affiliation: The second Xiangya Hospital, Central South University, 139# Renmin road, Changsha, Hunan, 410011, China.
authors.forename: Lingjiang
authors.initials: L
authors.lastname: Li
authors.affiliation: Department of Pathology, Northwestern University Feinberg School of Medicine, Chicago, 60611, USA.
authors.forename: Deyu
authors.initials: D
authors.lastname: Fang
mesh_terms: D000328:Adult; D000368:Aged; D001008:Anxiety Disorders / Q000175:diagnosis / Q000503:physiopathology*; D016022:Case-Control Studies; D002540:Cerebral Cortex / Q000503:physiopathology*; D039721:Diagnostic and Statistical Manual of Mental Disorders; D004569:Electroencephalography; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D017397:Prefrontal Cortex / Q000503:physiopathology*; D055815:Young Adult
keywords: Correlation dimension; Cortical functional activity; EEG nonlinear analysis; Generalized anxiety disorder; Psychiatry