title: Anhedonia in melancholic and non-melancholic depressive disorders.
abstract: BACKGROUND
  Anhedonia represents a core symptom of major depression and may be a potential marker for melancholia. However, current understanding of this construct in depressive sub-types is limited.
  
  
  METHODS
  Participants were recruited from the Black Dog Institute (Sydney) and Massachusetts General Hospital (Boston). Diagnostic groups were derived on the basis of agreement between clinician and DSM-IV diagnosis from structured interviews. Currently depressed unipolar melancholic, non-melancholic and healthy control participants were administered a probabilistic reward task (PRT) to assess a behavioural correlate of anhedonia-blunted reward-based learning. Self-reported measures of anhedonia, approach and avoidance motivation were completed by the Sydney sample.
  
  
  RESULTS
  Relative to healthy controls and non-melancholic participants, melancholic depressed participants had reduced response bias, highlighting blunted reward learning. Moreover, although non-melancholic participants were characterized by a delayed response bias, melancholic depressed participants failed to develop a bias throughout blocks. Response bias showed no associations with self-report measures of hedonic tone in depressed participants. Positive associations were observed between response bias, approach and avoidance motivation in non-melancholic participants only.
  
  
  CONCLUSIONS
  Possible medication, fatigue and anxiety effects were not controlled; small sample sizes; inclusion criteria may have excluded those with severe melancholia and led to underestimation of group differences.
  
  
  CONCLUSIONS
  Melancholia is characterised by a reduced ability to modulate behaviour as a function of reward, and the motivational salience of rewarding stimuli may differ across depressive sub-types. Results support the view that melancholia is a distinct sub-type. Further exploration of reward system functioning in depressive sub-types is warranted.
authors.affiliation: School of Psychiatry, University of New South Wales, NSW, Australia; Black Dog Institute, NSW, Australia; Centre for Psychological and Relationship Counselling, VIC, Australia. Electronic address: kat303@hotmail.com.
authors.forename: Kathryn
authors.initials: K
authors.lastname: Fletcher
authors.affiliation: School of Psychiatry, University of New South Wales, NSW, Australia; Black Dog Institute, NSW, Australia.
authors.forename: Gordon
authors.initials: G
authors.lastname: Parker
authors.affiliation: School of Psychiatry, University of New South Wales, NSW, Australia; Black Dog Institute, NSW, Australia.
authors.forename: Amelia
authors.initials: A
authors.lastname: Paterson
authors.affiliation: Massachusetts General Hospital, Boston, MA, USA; Harvard Medical School, Boston, MA, USA.
authors.forename: Maurizio
authors.initials: M
authors.lastname: Fava
authors.affiliation: The Mount Sinai Hospital, New York, NY, USA.
authors.forename: Dan
authors.initials: D
authors.lastname: Iosifescu
authors.affiliation: Massachusetts General Hospital, Boston, MA, USA; McLean Hospital, Belmont, MA, USA.
authors.forename: Diego A
authors.initials: DA
authors.lastname: Pizzagalli
mesh_terms: D000328:Adult; D059445:Anhedonia; D001007:Anxiety; D015986:Confounding Factors, Epidemiologic; D003866:Depressive Disorder / Q000175:diagnosis / Q000523:psychology; D003865:Major Depressive Disorder / Q000175:diagnosis* / Q000523:psychology*; D005221:Fatigue; D005260:Female; D006801:Humans; D008297:Male; D008404:Massachusetts; D009517:New South Wales; D012494:Sampling Studies; D057566:Self Report
keywords: Anhedonia; Depression; Melancholic; Motivation; Non-melancholic; Reward responsiveness