Event:

ntidepressant drug action has typically been considered at the neurochemical, cellular and molecular level. However, it is unclear how these changes become translated into the psychological changes in symptoms seen during treatment in depression.

Negative affective bias is commonly reported in depression, where patients are more likely to focus on negative vs positive emotional information. These biases have largely been explored using a cognitive psychological approach and form a target for psychological treatments such as CBT. However, recent evidence suggest that antidepressant drugs also affect negative affective bias early in treatment, using both behavioural and neural markers of change.. These early effects are predictive of later changes in clinical ratings of depression. Such findings raise the possibility that early remediation of negative bias may be a mechanism of antidepressant drug action and could be harnessed to screen and assess effects of novel candidate treatments.

Dysfunction in the reward system has also been reported in depression. This deficit can be exaggerated early in treatment with antidepressants but after longer term treatment these deficits are reversed i.e. normalised compared to healthy volunteers. These findings together suggest that drugs useful in the treatment of depression have early effects on emotional processing but the effects on reward are delayed. As such these processes may rely on separable underlying processes.

Compared to clinical rating scores, objective measurement of emotional and cognitive function with behavioural assessment and neuroimaging may provide more information about the early effects of antidepressants. These early effects may help understand mechanisms and profiles of established and novel treatments for depression.