@entity4270 in melancholic and non-melancholic XXXX .

@entity1 @entity308 @entity235 @entity4270 @entity148
BACKGROUND: @entity4270 represents a core symptom of major @entity308 and may be a potential marker for @entity308 . However, current understanding of this construct in depressive sub-types is limited. METHOD: @entity1 were recruited from the Black @entity235 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 @entity1 were administered a probabilistic reward task (PRT) to assess a behavioural correlate of @entity4270 -blunted reward-based learning. Self-reported measures of @entity4270 , approach and avoidance motivation were completed by the Sydney sample. RESULTS: Relative to healthy controls and non-melancholic @entity1 , melancholic depressed @entity1 had reduced response bias, highlighting blunted reward learning. Moreover, although non-melancholic @entity1 were characterized by a delayed response bias, melancholic depressed @entity1 failed to develop a bias throughout blocks. Response bias showed no associations with self-report measures of hedonic tone in depressed @entity1 . Positive associations were observed between response bias, approach and avoidance motivation in non-melancholic @entity1 only. LIMITATIONS: Possible medication, fatigue and @entity148 effects were not controlled; small sample sizes; inclusion criteria may have excluded those with severe @entity308 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 @entity308 is a distinct sub-type. Further exploration of reward system functioning in depressive sub-types is warranted.
