title: Negative ion treatment increases positive emotional processing in seasonal affective disorder.
abstract: BACKGROUND
  Antidepressant drug treatments increase the processing of positive compared to negative affective information early in treatment. Such effects have been hypothesized to play a key role in the development of later therapeutic responses to treatment. However, it is unknown whether these effects are a common mechanism of action for different treatment modalities. High-density negative ion (HDNI) treatment is an environmental manipulation that has efficacy in randomized clinical trials in seasonal affective disorder (SAD).
  
  
  METHODS
  The current study investigated whether a single session of HDNI treatment could reverse negative affective biases seen in seasonal depression using a battery of emotional processing tasks in a double-blind, placebo-controlled randomized study.
  
  
  RESULTS
  Under placebo conditions, participants with seasonal mood disturbance showed reduced recognition of happy facial expressions, increased recognition memory for negative personality characteristics and increased vigilance to masked presentation of negative words in a dot-probe task compared to matched healthy controls. Negative ion treatment increased the recognition of positive compared to negative facial expression and improved vigilance to unmasked stimuli across participants with seasonal depression and healthy controls. Negative ion treatment also improved recognition memory for positive information in the SAD group alone. These effects were seen in the absence of changes in subjective state or mood.
  
  
  CONCLUSIONS
  These results are consistent with the hypothesis that early change in emotional processing may be an important mechanism for treatment action in depression and suggest that these effects are also apparent with negative ion treatment in seasonal depression.
authors.affiliation: University Department of Psychiatry, Warneford Hospital, Oxford, UK. catherine.harmer@psych.ox.ac.uk
authors.forename: C J
authors.initials: CJ
authors.lastname: Harmer
authors.forename: M
authors.initials: M
authors.lastname: Charles
authors.forename: S
authors.initials: S
authors.lastname: McTavish
authors.forename: E
authors.initials: E
authors.lastname: Favaron
authors.forename: P J
authors.initials: PJ
authors.lastname: Cowen
mesh_terms: D000328:Adult; D000339:Affect; D000390:Air Ionization; D000704:Analysis of Variance; D000838:Anions / Q000627:therapeutic use; D004311:Double-Blind Method; D004644:Emotions; D005149:Facial Expression; D005260:Female; D006801:Humans; D008297:Male; D009483:Neuropsychological Tests / Q000706:statistics & numerical data; D010919:Placebos; D011569:Psychiatric Status Rating Scales; D011930:Reaction Time; D021641:Recognition, Psychology / Q000502:physiology; D016574:Seasonal Affective Disorder / Q000523:psychology / Q000628:therapy*; D016896:Treatment Outcome
chemical_list: D000838:Anions; D010919:Placebos