Depression-specific P300 deficits compared to other forms of internalizing psychopathology

Background

Depression involves dysfunctions in reward and cognitive processing, with event-related potentials (ERPs) demonstrating impaired reward positivity (RewP) and P300 components, reflecting deficits in processes such as reward consumption, decision making and motivation. However, depression is both a highly heterogenous disorder and highly comorbid with other internalizing disorders that are also characterized by similar deficits in RewP and P300, the specificity of these neural dysfunctions to depression and its symptom clusters, is less understood.

Methods

The current study employed a complex monetary gambling task, Gehring task, to examine depression-specific dysfunctions in decision making (choice-P300) and response to reward (RewP) within reward processing in a clinical sample of adults diagnosed with current depressive disorders (DEP; n = 107) compared to adults with other current internalizing disorders but no history of depression (non-DEP; n = 73).

Results

DEP participants exhibited significantly blunted P300 amplitude to mixed-choice (low and high reward) stimuli compared to non-DEP participants. No significant group differences emerged for P300 to other choice stimuli or for RewP. Moreover, reduced mixed-choice P300 was specifically associated with elevated anhedonic symptoms.

Limitations

Our work is cross-sectional in nature; therefore, we cannot establish a cause-effect relationship.

Conclusions

Findings suggest that within the internalizing disorders spectrum, depression is particularly characterized by deficits in decision making, indicated by reduced P300 amplitude, which is potentially reflecting elevations in anhedonia that does not characterize other internalizing disorders.