title: Suicide risk markers in major depressive disorder: a study of electrodermal activity and event-related potentials.
abstract: BACKGROUND
  Globally approximately 1 million people die annually by suicide. We studied both Electrodermal Activity (EDA) and Event-Related Potential (ERP) P3, together with an assessment of expressed anger as potential suicide risk predictors in Major Depressive Disorder (MDD) patients.
  
  
  METHODS
  In this controlled cross-sectional study, MDD inpatients were allocated to one of three groups: 1. history of 'hard attempted suicide' (e.g., hanging, stabbing; HAS), 2. 'soft attempted suicide' (poisoning; SAS) or 3. no attempted suicide (NAS), respectively. Patients were tested using both an auditory habituation paradigm (study 1) and an 'oddball task' (study 2). EDA Habituation Rate (HabR) and P3 amplitude differences evoked by both 'novel' and 'target' stimuli were computed between the first and second halves of the two studies. 'Anger' was assessed using State Trait Anger Expression Inventory (STAXI) subscales.
  
  
  RESULTS
  HabRs in both HAS (n=16) and SAS (n=16) were significantly lower than in NAS (n=18), in both study 1 and study 2, condition 'novel'. Decreases in P3 were also more pronounced in the HAS and SAS groups in study 1 and in the HAS group in study 2, 'novel' and 'target' condition. STAXI Anger In score was higher in HAS than in NAS.
  
  
  CONCLUSIONS
  The sample size is small; medication may influence EDA.
  
  
  CONCLUSIONS
  Both EDA and P3 habituated faster in MDD patients with a history of attempted suicide, and were associated with higher 'anger' scores. Our data is a starting point for developing further neurobiological assessments of suicide risk in clinical practice.
authors.affiliation: Dept. of Psychiatry and Psychotherapy I, University Hospital Ulm, Ravensburg, Germany. martin.jandl@uni-ulm.de
authors.forename: Martin
authors.initials: M
authors.lastname: Jandl
authors.forename: Juergen
authors.initials: J
authors.lastname: Steyer
authors.forename: Wolfgang P
authors.initials: WP
authors.lastname: Kaschka
mesh_terms: D000328:Adult; D000786:Anger / Q000502:physiology*; D001143:Arousal / Q000502:physiology; D003430:Cross-Sectional Studies; D003865:Major Depressive Disorder / Q000175:diagnosis / Q000503:physiopathology* / Q000523:psychology*; D004569:Electroencephalography; D018913:Event-Related Potentials, P300 / Q000502:physiology*; D005260:Female; D005712:Galvanic Skin Response / Q000502:physiology*; D005858:Germany; D006801:Humans; D008297:Male; D008875:Middle Aged; D018570:Risk Assessment; D013406:Suicide, Attempted / Q000517:prevention & control / Q000523:psychology*