title: Anxious and depressive disorders and their comorbidity: effect on central nervous system noradrenergic function.
abstract: BACKGROUND
  Although comorbidity of anxiety with depression is common, investigations of physiologic abnormalities related specifically to comorbidity are rare. This study examined relationships of DSM-IV-defined depression, anxiety, and their comorbidity to noradrenergic function measured by blunting of the growth hormone (GH) response to the alpha2 adrenoreceptor agonist (and imidazoline receptor agent) clonidine and by blood pressure and symptom responses.
  
  
  METHODS
  Fifteen subjects with pure social anxiety or panic disorder, 15 with pure major depression, and 18 with both depression and anxiety were compared with healthy control subjects matched for age and gender. Other factors known to affect GH (weight, menstrual status, prior antidepressant, or other drug exposure) were controlled.
  
  
  RESULTS
  Anxiety produced GH blunting, but depression was associated with normal GH responses. The comorbid state did not affect results beyond the impact of anxiety. Preclonidine stress-related GH elevations were observed, to the greatest degree in anxious subjects. Relevant symptom, but not blood pressure, changes were significantly associated with blunting.
  
  
  CONCLUSIONS
  With use of pure depression and anxiety groups and careful control of other factors known to affect GH, these results demonstrate central nervous system noradrenergic dysfunction in anxiety disorders. In contrast to less rigorously controlled studies, noradrenergic function in depression was normal.
authors.affiliation: Department of Psychiatry, University of Michigan Medical Center, Ann Arbor, Michigan, USA. ocameron@umich.edu
authors.forename: Oliver G
authors.initials: OG
authors.lastname: Cameron
authors.forename: James L
authors.initials: JL
authors.lastname: Abelson
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: Young
mesh_terms: D000316:Adrenergic alpha-Agonists / Q000494:pharmacology; D000328:Adult; D000704:Analysis of Variance; D001007:Anxiety / Q000188:drug therapy / Q000453:epidemiology* / Q000378:metabolism; D016022:Case-Control Studies; D002490:Central Nervous System / Q000187:drug effects / Q000378:metabolism*; D003000:Clonidine / Q000494:pharmacology / Q000627:therapeutic use; D015897:Comorbidity; D003866:Depressive Disorder / Q000188:drug therapy / Q000453:epidemiology* / Q000378:metabolism; D039721:Diagnostic and Statistical Manual of Mental Disorders; D005260:Female; D013006:Growth Hormone / Q000378:metabolism; D006801:Humans; D008297:Male; D009638:Norepinephrine / Q000502:physiology*; D010147:Pain Measurement; D010555:Personality Inventory; D011569:Psychiatric Status Rating Scales; D012043:Regression, Psychology; D012894:Sleep Stages / Q000187:drug effects
chemical_list: D000316:Adrenergic alpha-Agonists; D013006:Growth Hormone; D003000:Clonidine; D009638:Norepinephrine