Implicit and explicit memory biases in mixed anxiety–depression

Background: This study investigated and compared implicit and explicit memory biases in anxiety, depression and mixed anxiety–depression. Method: Outpatients who were either depressed only (n=18), anxious only (n=18) or mixed (anxious and depressed) (n=18) were compared to normal controls (n=18) on self-report measures and typical experimental tasks assessing memory biases. The implicit memory test was a word identification task and the explicit memory test was an incidental free recall with depression relevant, anxiety relevant, emotional positive and neutral words. Results: The depressed group showed a positive implicit memory bias and a mood-congruent bias at free recall. The anxious group presented an overall higher priming effect in the implicit memory test, whilst the mixed group exhibited no difference in the quantity of priming effect compared to normal controls and recalled more anxious relevant words than other word types. Limitations: Because of the dimensional perspective adopted in the present study, the mixed group was composed of both DSM-IV sub-threshold (n=5) and supra-threshold (n=13) patients. Conclusions: These results show a specific pattern for the mixed group and suggest that mixed anxiety–depression represents a distinct clinical group.