title: Depression is related to an absence of optimistically biased belief updating about future life events.
abstract: BACKGROUND
  When challenged with information about the future, healthy participants show an optimistically biased updating pattern, taking desirable information more into account than undesirable information. However, it is unknown how patients suffering from major depressive disorder (MDD), who express pervasive pessimistic beliefs, update their beliefs when receiving information about their future. Here we tested whether an optimistically biased information processing pattern found in healthy individuals is absent in MDD patients.
  
  
  METHODS
  MDD patients (n = 18; 13 medicated; eight with co-morbid anxiety disorder) and healthy controls (n = 19) estimated their personal probability of experiencing 70 adverse life events. After each estimate participants were presented with the average probability of the event occurring to a person living in the same sociocultural environment. This information could be desirable (i.e. average probability better than expected) or undesirable (i.e. average probability worse than expected). To assess how desirable versus undesirable information influenced beliefs, participants estimated their personal probability of experiencing the 70 events a second time.
  
  
  RESULTS
  Healthy controls showed an optimistic bias in updating, that is they changed their beliefs more toward desirable versus undesirable information. Overall, this optimistic bias was absent in MDD patients. Symptom severity correlated with biased updating: more severely depressed individuals showed a more pessimistic updating pattern. Furthermore, MDD patients estimated the probability of experiencing adverse life events as higher than healthy controls.
  
  
  CONCLUSIONS
  Our findings raise the intriguing possibility that optimistically biased updating of expectations about one's personal future is associated with mental health.
authors.affiliation: Department of Education and Psychology, Freie Universität Berlin, Germany.
authors.forename: C W
authors.initials: CW
authors.lastname: Korn
authors.affiliation: Department of Cognitive, Perceptual and Brain Sciences, Division of Psychology and Language Sciences, University College London, UK.
authors.forename: T
authors.initials: T
authors.lastname: Sharot
authors.affiliation: Berlin School of Mind and Brain, Humboldt Universität zu Berlin, Germany.
authors.forename: H
authors.initials: H
authors.lastname: Walter
authors.affiliation: Department of Education and Psychology, Freie Universität Berlin, Germany.
authors.forename: H R
authors.initials: HR
authors.lastname: Heekeren
authors.affiliation: Wellcome Trust Centre for Neuroimaging, Institute of Neurology, University College London, UK.
authors.forename: R J
authors.initials: RJ
authors.lastname: Dolan
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D059031:Anticipation, Psychological / Q000502:physiology*; D001008:Anxiety Disorders / Q000150:complications / Q000523:psychology; D016022:Case-Control Studies; D003865:Major Depressive Disorder / Q000150:complications / Q000523:psychology*; D005260:Female; D065026:Hope; D006801:Humans; D007092:Imagination; D007361:Intelligence Tests; D007406:Interview, Psychological; D008016:Life Change Events; D008297:Male; D008960:Models, Psychological; D011336:Probability; D011569:Psychiatric Status Rating Scales; D012718:Set, Psychology; D012720:Severity of Illness Index